The Preparation of a Highly Efficient Ag 3 PO 4 / Ag / Bi 2 O 2 CO 3 Photo-Catalyst and the Study of Its PhotoCatalytic Organic Synthesis Reaction Driven by Visible Light

Ag3PO4/Ag/Bi2O2CO3 composites were prepared by a hydrothermal and precipitation method. The morphology, structure, and valence state of the photo-catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) specific surface areas, and UV-vis diffuse reflectance spectra (UV-vis DRS). They were applied as heterogeneous catalysts in the synthesis of esters from aldehydes (or alcohols) and alcohols and the synthesis of imines from alcohols and amines under visible light irradiation. The photo-catalytic activities of the esterification reactions of aldehydes and alcohols were heavily dependent on the loading of Ag3PO4/Ag/Bi2O2CO3 as well as the intensity and wavelength of the visible light. Furthermore, their conversion under visible light irradiation was superior to that in the dark. Herein a reaction mechanism from aldehydes and alcohols to esters was proposed, and the Ag3PO4/Ag/Bi2O2CO3 catalysts could be used six times without a significant decrease in activity. Using these catalysts under visible light could motivate future studies to develop efficient recyclable photo-catalysts and facilitate many synthetic organic reactions.


Introduction
As two of the most important functional groups in organic chemistry, ester and amine groups have been widely used in the synthesis of fine chemicals, pharmaceutical intermediates, and polymers [1,2].In recent years, the question of how to produce esters and amines rapidly, effectively and in an energy-efficient manner has attracted great attention [3].Traditionally, esters have been produced through the reaction of acid derivatives (such as acid chlorides or anhydrides) and alcohols, while imines have been created through the condensation of aldehydes or ketones and amines.However, myriads of by-products are generated as part of these synthetic processes, which both wastes resources and creates environmental pollution [4][5][6].Recently, precious metal catalysts supported on carriers (such as Ir [7,8], Cu [9,10], Pd [11], and Au [12]) have been applied in the above-mentioned synthetic processes.However, the reaction conditions have been severe, for example, equivalents of metal salts or metal oxides (such as KMnO 4 [13], MnO 2 [14] or KHSO 4 [15]) were added as oxidants, which created many by-products in the reaction, thus making the utilization ratio of the raw material unfavorable [16][17][18][19][20]. Therefore, it is important to discover an alternative to produce esters from aldehydes (or alcohols) and alcohols, and imines from alcohols and amines by using solid catalysts for the purposes of green chemistry and organic synthesis under milder conditions.Photo-catalysis is of interest in green chemistry as it can improve catalytic efficiency and use visible light.Photo-catalysis has been regarded as one of the most effective ways to address energy shortages and environmental pollutions [21,22].Many researchers have expressed an interest in Bi materials due to their special semiconductor layered crystal structures and d 10 electron configurations, which enable them to respond to light [23][24][25].Consisting of (Bi 2 O 2 ) 2+ and (CO 3 ) 2− layers, Bi 2 O 2 CO 3 [26][27][28][29], a member of the stratified or Aurivillius-related oxide family, has demonstrated good performance in antibacterial [28,29] and environmental applications [26,[30][31][32][33].However, it has a poor ability to separate electrons and holes which was poor after excitation by visible light, therefore, many efforts have been made to decrease its recombination of electrons and holes in order to enhance its photo-catalytic activity.These efforts have included the construction of two-dimensional (2D) or three-dimensional (3D) structures [26,[30][31][32][33], and the interaction of Bi 2 O 2 CO 3 with BiVO 4 [34], graphene [35], Fe 3 O 4 [36], and BiOCl [37] among others.Recently, Ag-based compounds (such as Ag 3 PO 4 [38] and Ag@AgX (X = Cl, Br, I)) [39][40][41] have been widely studied as theoretically promising photo-catalytic materials [42], where the filled d 10 electronic configuration unique to Ag + could take part in the formation and hybridization of the energy band structure (such as Ag-based composites) [43][44][45].The semiconductor Ag 3 PO 4 , with a band gap of 2.45 eV, could be activated by visible light, retrieve O 2 from water, and degrade organic dyes [46].Furthermore, its solid-state structure could improve the transfer capability of the photo-generated electrons through interactions between the metal and semiconductor materials.Therefore, optimizing the interaction between the metals and semiconductors is of great importance [22].
In the composites, Ag 3 PO 4 and Bi 2 O 2 CO 3 the composites were excited by visible light, and electrons and holes were transferred by Ag.Under visible light irradiation, electrons and holes were generated by Ag 3 PO 4 , the Fermi level of Ag was more positive than the conduction band of Ag 3 PO 4 , so electrons on the conduction band of Ag 3 PO 4 could transfer to Ag.Similarly, under visible light irradiation, electrons and holes were also generated by Bi 2 O 2 CO 3 , but the Fermi level of Ag was more negative than the valence band of Bi 2 O 2 CO 3 , so the holes were easily transferred to Ag. Ag can act as a trap for electrons as usually happens in semiconductor/metal nanoparticle systems.Therefore, the composite material had a strong redox ability [34,37,47].Through the analysis of each component of the composite material, it was found that a variety of organic reactions could be carried out under visible light irradiation.The esterification of aldehydes (or alcohols) and alcohols, and the amination of alcohols and amines were detected over Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 under visible light irradiation.Additionally, the effects of light intensity and wavelength on the esterification procedure of aldehydes and alcohols were examined.The conversion sped up when the light intensity increased, confirming that the reaction was initiated by visible light, thus, light between 400 and 650 nm played an important role.Furthermore, this catalyst continued to manifest high activity after being used six times.Finally, a possible mechanism from aldehydes and alcohols to esters was proposed, based on the experimental evidence and correlated documents.

Phase Stucture (XRD)
The phase structures of different metals or metal composites were detected by X-ray diffraction (XRD) (Rigaku Industrial Corporation, Osaka, Japan) (Figure 1).Sharp and intense diffraction peaks of the prepared Bi 2 O 2 CO 3 appeared, which were ascribed to a tetragonal phase of Bi 2 O 2 CO 3 (JCPDS Card No. 41-1488, a = 3.865 Å, b = 3.865 Å, and c = 3.675 Å).Four apparent diffraction peaks were observed at 23.90 • , 30.25 • , 32.73 • , and 46.97 • , which could be assigned as the (011), (013), (110), and (020) lattice planes of tetragonal Bi 2 O 2 CO 3 , respectively.In addition, XRD peaks at 23.90 • , 30.25 • , 32.73 • , and 46.97 • were observed for the composite of Ag on the Bi 2 O 2 CO 3 surface.However, no Ag peaks were observed, which may have been a consequence of overly small Ag particles [48].The diffraction peaks of the Ag 3 PO 4 composite on the Bi 2 O 2 CO 3 surface were the same as those of cubic Ag 3 PO 4 (JCPDS

Chemical Composition (XPS)
X-ray photoelectron spectroscopy (XPS) was performed to assay the chemical composition and chemical state of the Ag element in the Ag3PO4/Ag/Bi2O2CO3 composites.The Bi 4f XPS spectra are elaborated in Figure 2a, where two peaks at 159.58 and 164.78 eV were observed.Thus, the dominant chemical state of Bi in the Ag3PO4/Ag/Bi2O2CO3 catalyst can be regarded as +3 [49].The peaks at 368.34 and 374.50 eV were caused by Ag 3d5/2 and Ag 3d3/2, respectively (Figure 2b).The Ag 3d5/2 peaks were further separated into two peaks at 368.2 and 368.55 eV, and the Ag 3d3/2 peak was also separated into two peaks at 374.2 and 374.5 eV.The peaks at 368.2 and 374.2 eV were caused by the Ag + of Ag3PO4, and the peaks at 368.55 and 374.5 eV corresponded to Ag 0 [50,51].In Figure 2c, a single O 1s peak at 531.38 eV was observed, and attributed to the carbonate species [52].A broad P 2p peak within the range of 131.38 to 136.18 eV (Figure 2d) was observed for the Ag3PO4/Ag/Bi2O2CO3 sample, which corresponded to the phosphorus (P) of Ag3PO4 [53].The presence of Ag and Ag3PO4 in the prepared composites was confirmed by XPS analysis.Intensity/(a.u.) 2 Theta/(degree) The phase structures of the catalysts prepared with different silver phosphate loadings were also investigated by XRD (Figure 1b).The cubic Ag 3 PO 4 diffraction peaks were clearly detected, and the intensity of these peaks gradually increased with increasing Ag 3 PO 4 ratio in the composite.

Chemical Composition (XPS)
X-ray photoelectron spectroscopy (XPS) was performed to assay the chemical composition and chemical state of the Ag element in the Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 composites.The Bi 4f XPS spectra are elaborated in Figure 2a, where two peaks at 159.58 and 164.78 eV were observed.Thus, the dominant chemical state of Bi in the Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 catalyst can be regarded as +3 [49].The peaks at 368.34 and 374.50 eV were caused by Ag 3d 5/2 and Ag 3d 3/2 , respectively (Figure 2b).The Ag 3d 5/2 peaks were further separated into two peaks at 368.2 and 368.55 eV, and the Ag 3d 3/2 peak was also separated into two peaks at 374.2 and 374.5 eV.The peaks at 368.2 and 374.2 eV were caused by the Ag + of Ag 3 PO 4 , and the peaks at 368.55 and 374.5 eV corresponded to Ag 0 [50,51].In Figure 2c, a single O 1s peak at 531.38 eV was observed, and attributed to the carbonate species [52].A broad P 2p peak within the range of 131.38 to 136.18 eV (Figure 2d) was observed for the Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 sample, which corresponded to the phosphorus (P) of Ag 3 PO 4 [53].The presence of Ag and Ag 3 PO 4 in the prepared composites was confirmed by XPS analysis.

Morphological Structure (TEM, Energy Dispersive X-ray Spectrum (EDX), and SEM)
The morphology, crystal form, and composition of the composites were elucidated by transmission electron microscopy (TEM), energy dispersive X-ray spectrum (EDX) (Figure 3a-3k), and Scanning electron microscopy (SEM) (Figure S1a-S1j), respectively.The lattice fringes of d = 0.274 and 0.297 nm were attributed to the (110) and (013) planes of the Bi2O2CO3 nano-sheets (Figure 3b).This phenomenon was consistent with the XRD results, confirming a successful Bi2O2CO3 synthesis.The lattice fringe of d = 0.237 nm was attributed to the (111) plane of Ag (Figure 3d) and those of d = 0.274 nm (0.269 nm) and 0.301 nm (0.299 nm, 0.297 nm) were attributed to the (210) and Intensity/(a.u.) Binding energy/(eV) 2.3.Morphological Structure (TEM, Energy Dispersive X-ray Spectrum (EDX), and SEM) The morphology, crystal form, and composition of the composites were elucidated by transmission electron microscopy (TEM), energy dispersive X-ray spectrum (EDX) (Figure 3a-3k), and Scanning electron microscopy (SEM) (Figure S1a-S1j), respectively.The lattice fringes of d = 0.274 and 0.297 nm were attributed to the (110) and (013) planes of the Bi 2 O 2 CO 3 nano-sheets (Figure 3b).This phenomenon was consistent with the XRD results, confirming a successful Bi 2 O 2 CO 3 synthesis.The lattice fringe of d = 0.237 nm was attributed to the (111) plane of Ag (Figure 3d) and those of d = 0.274 nm (0.269 nm) and 0.301 nm (0.299 nm, 0.297 nm) were attributed to the (210) and (200) (200) planes of cubic Ag3PO4 (Figure 3f,h,j).Therefore, Ag3PO4 was successfully loaded onto the Bi2O2CO3 material.The EDX image (Figure 3k) of the 71 wt% Ag3PO4/Ag/Bi2O2CO3 composite demonstrated that Ag3PO4, Ag, and Bi2O2CO3 particles were all present within the catalyst, which confirmed the successful formation of a three-phase nanoparticle hetero-structure.

Specific BET Surface Areas
The BET surface areas of these catalysts are given in Table S1.The surface area of pure Bi2O2CO3 was 51.05 m 2 •g −1 , and it dwindled to 46.11 m 2 •g −1 after the Ag loading onto the Bi2O2CO3 surface.The decrease in the surface area of Ag/Bi2O2CO3 predominantly resulted from the Ag loading onto the Bi2O2CO3 surface.With the increase in Ag3PO4 mass ratio, the corresponding surface area decreased dramatically (Table S1), possibly as a result of filling Ag3PO4 gradually into the mesoporous structure of Bi2O2CO3.

UV-Vis DRS and Band Gap
UV-vis diffuse reflectance spectra (DRS) were used to calculate the band gap and light absorbing ability of the photo-catalysts.An absorption peak appeared within the UV range for all samples (Figure 4).For 10 wt% Ag/Bi2O2CO3, the absorption within the 400-800 nm range was attributed to the surface plasmon resonance (SPR) of the Ag nanoparticles.The absorption of 64 wt% Ag3PO4/Bi2O2CO3 was greater than that of Bi2O2CO3 within the 400-800 nm range due to the presence of Ag3PO4.In addition, a stronger absorption within the 400-800 nm range occurred for the 10 wt% Ag/Bi2O2CO3 and 64 wt% Ag3PO4/Bi2O2CO3 composites.Furthermore, a much stronger absorption was present within the 400-800 nm range for the 71 wt% Ag3PO4/Ag/Bi2O2CO3 composite compared to 64 wt% Ag3PO4/Bi2O2CO3.Overall, a strong absorption capacity of the 71 wt% Ag3PO4/Ag/Bi2O2CO3 composite was detected within the visible light range (Figure 4a).

Specific BET Surface Areas
The BET surface areas of these catalysts are given in Table S1.The surface area of pure Bi 2 O 2 CO 3 was 51.05 m 2 •g −1 , and it dwindled to 46.11 m 2 •g −1 after the Ag loading onto the Bi 2 O 2 CO 3 surface.The decrease in the surface area of Ag/Bi 2 O 2 CO 3 predominantly resulted from the Ag loading onto the Bi 2 O 2 CO 3 surface.With the increase in Ag 3 PO 4 mass ratio, the corresponding surface area decreased dramatically (Table S1), possibly as a result of filling Ag 3 PO 4 gradually into the mesoporous structure of Bi 2 O 2 CO 3 .

UV-Vis DRS and Band Gap
UV-vis diffuse reflectance spectra (DRS) were used to calculate the band gap and light absorbing ability of the photo-catalysts.An absorption peak appeared within the UV range for all samples (Figure 4).For 10 wt % Ag/Bi 2 O 2 CO 3 , the absorption within the 400-800 nm range was attributed to the surface plasmon resonance (SPR) of the Ag nanoparticles.The absorption of 64 wt % Ag 3 PO 4 /Bi 2 O 2 CO 3 was greater than that of Bi 2 O 2 CO 3 within the 400-800 nm range due to the presence of Ag 3 PO 4 .In addition, a stronger absorption within the 400-800 nm range occurred for the 10 wt % Ag/Bi 2 O 2 CO 3 and 64 wt % Ag 3 PO 4 /Bi 2 O 2 CO 3 composites.Furthermore, a much stronger absorption was present within the 400-800 nm range for the 71 wt % Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 composite compared to 64 wt % Ag 3 PO 4 /Bi 2 O 2 CO 3 .Overall, a strong absorption capacity of the 71 wt % Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 composite was detected within the visible light range (Figure 4a).

Specific BET Surface Areas
The BET surface areas of these catalysts are given in Table S1.The surface area of pure Bi2O2CO3 was 51.05 m 2 •g −1 , and it dwindled to 46.11 m 2 •g −1 after the Ag loading onto the Bi2O2CO3 surface.The decrease in the surface area of Ag/Bi2O2CO3 predominantly resulted from the Ag loading onto the Bi2O2CO3 surface.With the increase in Ag3PO4 mass ratio, the corresponding surface area decreased dramatically (Table S1), possibly as a result of filling Ag3PO4 gradually into the mesoporous structure of Bi2O2CO3.

UV-Vis DRS and Band Gap
UV-vis diffuse reflectance spectra (DRS) were used to calculate the band gap and light absorbing ability of the photo-catalysts.An absorption peak appeared within the UV range for all samples (Figure 4).For 10 wt% Ag/Bi2O2CO3, the absorption within the 400-800 nm range was attributed to the surface plasmon resonance (SPR) of the Ag nanoparticles.The absorption of 64 wt% Ag3PO4/Bi2O2CO3 was greater than that of Bi2O2CO3 within the 400-800 nm range due to the presence of Ag3PO4.In addition, a stronger absorption within the 400-800 nm range occurred for the 10 wt% Ag/Bi2O2CO3 and 64 wt% Ag3PO4/Bi2O2CO3 composites.Furthermore, a much stronger absorption was present within the 400-800 nm range for the 71 wt% Ag3PO4/Ag/Bi2O2CO3 composite compared to 64 wt% Ag3PO4/Bi2O2CO3.Overall, a strong absorption capacity of the 71 wt% Ag3PO4/Ag/Bi2O2CO3 composite was detected within the visible light range (Figure 4a).The optical absorption near the band edge was in agreement with Equation (1) for a crystalline semiconductor [54].
Here, α, ν, A, n, and Eg represented the diffuse absorption coefficient, the light frequency, a proportionality constant, an integer (n = 1, 2, 4, 6), and the band gap energy, respectively.In the case of the Bi2O2CO3 material [27], the value of n was 4. As shown in Figure 4b, the estimated Eg was 3.25 eV for Bi2O2CO3, which was consistent with the literature value [32,35].The absorption peak of the 64 wt% Ag3PO4/Bi2O2CO3 composite within the 400-800 nm range was attributed to Ag3PO4, while the absorption peak between 200 and 400 nm was ascribed to Bi2O2CO3 and Ag3PO4.The absorption peak of cubic Ag3PO4 within the 400-800 nm range was observed (Figure 4c).Further analysis demonstrated that the absorption peak of the 73 wt% Ag3PO4/Ag/Bi2O2CO3 catalyst was weaker than that of the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalyst.Therefore, the strongest light absorption corresponded to the 71 wt% Ag3PO4/Ag/Bi2O2CO3 composite, which further explained why the catalytic activity of this material was better than that of the 73 wt% Ag3PO4/Ag/Bi2O2CO3 composite.

Esterification of Aldehydes and Alcohols
The photo-catalytic performance of the Ag3PO4/Ag/Bi2O2CO3 composites was investigated by the photo-catalytic oxidative esterification of benzaldehyde (1.5 mmol) and methanol (8 mL) under certain initial conditions under visible light (including 64 wt% Ag3PO4/Ag/Bi2O2CO3 (50 mg), temperature of 35 ± 3 °C, and an Ar atmosphere).The products were detected by gas chromatography (GC).A benzaldehyde conversion of 80.6% was achieved after 48 h with a corresponding selectivity of 99.5% for methyl benzoate.The reaction conditions were optimized by   The optical absorption near the band edge was in agreement with Equation (1) for a crystalline semiconductor [54].
Here, α, ν, A, n, and E g represented the diffuse absorption coefficient, the light frequency, a proportionality constant, an integer (n = 1, 2, 4, 6), and the band gap energy, respectively.In the case of the Bi 2 O 2 CO 3 material [27], the value of n was 4. As shown in Figure 4b, the estimated E g was 3.25 eV for Bi 2 O 2 CO 3 , which was consistent with the literature value [32,35].The absorption peak of the 64 wt % Ag 3 PO 4 /Bi 2 O 2 CO 3 composite within the 400-800 nm range was attributed to Ag 3 PO 4 , while the absorption peak between 200 and 400 nm was ascribed to Bi 2 O 2 CO 3 and Ag 3 PO 4 .The absorption peak of cubic Ag 3 PO 4 within the 400-800 nm range was observed (Figure 4c).Further analysis demonstrated that the absorption peak of the 73 wt % Ag    C, and an Ar atmosphere).The products were detected by gas chromatography (GC).A benzaldehyde conversion of 80.6% was achieved after 48 h with a corresponding selectivity of 99.5% for methyl benzoate.The reaction conditions were optimized by choosing 8 mL of methanol as a solvent, 1.0 mmol of benzaldehyde as a reactant, and 30 mg of catalyst under advantageous conditions such as 35 ± 3 • C, an Ar atmosphere, and normal atmospheric pressure.
The reactions of benzaldehyde with different alcohols were investigated by using 71 wt % Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 .Methanol provided the desired products at a higher conversion (Table 1, entries 1-6).The corresponding benzoate esters were produced by ethanol, isopropanol, butanol, octanol, and 2-octanol under visible light irradiation.The nucleophilicity between the secondary alcohol and the long chain carbon alcohol was weak; however, aldehyde conversions were below 10% in all cases when the reactions were performed in the dark (Table 1).Different substituted benzaldehydes were transformed to the corresponding esters under the same conditions (Table 1, entries 7-12).Aldehyde conversions of 95.5% and 99.4% were reached (Table 1, entries 7 and 8).The substituted benzaldehyde conversions with an electron-withdrawing group reached only 66.2% and 48.6% (Table 1, entries 9 and 10).In contrast, the substituted benzaldehydes with electron-donating groups proved more advantageous for the esterification reaction than those with electron-withdrawing groups.The more stable the radical resonance structure, the higher was the reactant conversion.In contrast, when electron-withdrawing groups were located at the counter point of the benzene ring, free radical resonance structures were formed that were unstable and disadvantageous for the esterification reaction.Even reactive hetero-cycles with a long-chain aliphatic aldehyde, such as furfuraldehyde or valeraldehyde, could be transformed into the corresponding esters with modest conversions (52.6% and 40.1%,Table 1, entries 11 and 12).Both electron-withdrawing and electron-donating benzylic aldehydes worked for this transformation using silver photo-catalysts.choosing 8 mL of methanol as a solvent, 1.0 mmol of benzaldehyde as a reactant, and 30 mg of catalyst under advantageous conditions such as 35 ± 3 °C, an Ar atmosphere, and normal atmospheric pressure.
The reactions of benzaldehyde with different alcohols were investigated by using 71 wt% Ag3PO4/Ag/Bi2O2CO3.Methanol provided the desired products at a higher conversion (Table 1, entries 1-6).The corresponding benzoate esters were produced by ethanol, isopropanol, butanol, octanol, and 2-octanol under visible light irradiation.The nucleophilicity between the secondary alcohol and the long chain carbon alcohol was weak; however, aldehyde conversions were below 10% in all cases when the reactions were performed in the dark (Table 1).Different substituted benzaldehydes were transformed to the corresponding esters under the same conditions (Table 1, entries 7-12).Aldehyde conversions of 95.5% and 99.4% were reached (Table 1, entries 7 and 8).The substituted benzaldehyde conversions with an electron-withdrawing group reached only 66.2% and 48.6% (Table 1, entries 9 and 10).In contrast, the substituted benzaldehydes with electron-donating groups proved more advantageous for the esterification reaction than those with electron-withdrawing groups.The more stable the radical resonance structure, the higher was the reactant conversion.In contrast, when electron-withdrawing groups were located at the counter point of the benzene ring, free radical resonance structures were formed that were unstable and disadvantageous for the esterification reaction.Even reactive hetero-cycles with a long-chain aliphatic aldehyde, such as furfuraldehyde or valeraldehyde, could be transformed into the corresponding esters with modest conversions (52.6% and 40.1%,Table 1, entries 11 and 12).Both electron-withdrawing and electron-donating benzylic aldehydes worked for this transformation using silver photo-catalysts.Reaction conditions: aldehyde (1.0 mmol) and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to alcohol (8 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10  choosing 8 mL of methanol as a solvent, 1.0 mmol of benzaldehyde as a reactant, and 30 mg of catalyst under advantageous conditions such as 35 ± 3 °C, an Ar atmosphere, and normal atmospheric pressure. The reactions of benzaldehyde with different alcohols were investigated by using 71 wt% Ag3PO4/Ag/Bi2O2CO3.Methanol provided the desired products at a higher conversion (Table 1, entries 1-6).The corresponding benzoate esters were produced by ethanol, isopropanol, butanol, octanol, and 2-octanol under visible light irradiation.The nucleophilicity between the secondary alcohol and the long chain carbon alcohol was weak; however, aldehyde conversions were below 10% in all cases when the reactions were performed in the dark (Table 1).Different substituted benzaldehydes were transformed to the corresponding esters under the same conditions (Table 1, entries 7-12).Aldehyde conversions of 95.5% and 99.4% were reached (Table 1, entries 7 and 8).The substituted benzaldehyde conversions with an electron-withdrawing group reached only 66.2% and 48.6% (Table 1, entries 9 and 10).In contrast, the substituted benzaldehydes with electron-donating groups proved more advantageous for the esterification reaction than those with electron-withdrawing groups.The more stable the radical resonance structure, the higher was the reactant conversion.In contrast, when electron-withdrawing groups were located at the counter point of the benzene ring, free radical resonance structures were formed that were unstable and disadvantageous for the esterification reaction.Even reactive hetero-cycles with a long-chain aliphatic aldehyde, such as furfuraldehyde or valeraldehyde, could be transformed into the corresponding esters with modest conversions (52.6% and 40.1%,Table 1, entries 11 and 12).Both electron-withdrawing and electron-donating benzylic aldehydes worked for this transformation using silver photo-catalysts.choosing 8 mL of methanol as a solvent, 1.0 mmol of benzaldehyde as a reactant, and 30 mg of catalyst under advantageous conditions such as 35 ± 3 °C, an Ar atmosphere, and normal atmospheric pressure.
The reactions of benzaldehyde with different alcohols were investigated by using 71 wt% Ag3PO4/Ag/Bi2O2CO3.
Methanol provided the desired products at a higher conversion (Table 1, entries 1-6).The corresponding benzoate esters were produced by ethanol, isopropanol, butanol, octanol, and 2-octanol under visible light irradiation.The nucleophilicity between the secondary alcohol and the long chain carbon alcohol was weak; however, aldehyde conversions were below 10% in all cases when the reactions were performed in the dark (Table 1).Different substituted benzaldehydes were transformed to the corresponding esters under the same conditions (Table 1, entries 7-12).Aldehyde conversions of 95.5% and 99.4% were reached (Table 1, entries 7 and 8).The substituted benzaldehyde conversions with an electron-withdrawing group reached only 66.2% and 48.6% (Table 1, entries 9 and 10).In contrast, the substituted benzaldehydes with electron-donating groups proved more advantageous for the esterification reaction than those with electron-withdrawing groups.The more stable the radical resonance structure, the higher was the reactant conversion.In contrast, when electron-withdrawing groups were located at the counter point of the benzene ring, free radical resonance structures were formed that were unstable and disadvantageous for the esterification reaction.Even reactive hetero-cycles with a long-chain aliphatic aldehyde, such as furfuraldehyde or valeraldehyde, could be transformed into the corresponding esters with modest conversions (52.6% and 40.1%,Table 1, entries 11 and 12).Both electron-withdrawing and electron-donating benzylic aldehydes worked for this transformation using silver photo-catalysts.choosing 8 mL of methanol as a solvent, 1.0 mmol of benzaldehyde as a reactant, and 30 mg of catalyst under advantageous conditions such as 35 ± 3 °C, an Ar atmosphere, and normal atmospheric pressure.
The reactions of benzaldehyde with different alcohols were investigated by using 71 wt% Ag3PO4/Ag/Bi2O2CO3.
Methanol provided the desired products at a higher conversion (Table 1, entries 1-6).The corresponding benzoate esters were produced by ethanol, isopropanol, butanol, octanol, and 2-octanol under visible light irradiation.The nucleophilicity between the secondary alcohol and the long chain carbon alcohol was weak; however, aldehyde conversions were below 10% in all cases when the reactions were performed in the dark (Table 1).Different substituted benzaldehydes were transformed to the corresponding esters under the same conditions (Table 1, entries 7-12).Aldehyde conversions of 95.5% and 99.4% were reached (Table 1, entries 7 and 8).The substituted benzaldehyde conversions with an electron-withdrawing group reached only 66.2% and 48.6% (Table 1, entries 9 and 10).In contrast, the substituted benzaldehydes with electron-donating groups proved more advantageous for the esterification reaction than those with electron-withdrawing groups.The more stable the radical resonance structure, the higher was the reactant conversion.In contrast, when electron-withdrawing groups were located at the counter point of the benzene ring, free radical resonance structures were formed that were unstable and disadvantageous for the esterification reaction.Even reactive hetero-cycles with a long-chain aliphatic aldehyde, such as furfuraldehyde or valeraldehyde, could be transformed into the corresponding esters with modest conversions (52.6% and 40.1%,Table 1, entries 11 and 12).Both electron-withdrawing and electron-donating benzylic aldehydes worked for this transformation using silver photo-catalysts.choosing 8 mL of methanol as a solvent, 1.0 mmol of benzaldehyde as a reactant, and 30 mg of catalyst under advantageous conditions such as 35 ± 3 °C, an Ar atmosphere, and normal atmospheric pressure.
The reactions of benzaldehyde with different alcohols were investigated by using 71 wt% Ag3PO4/Ag/Bi2O2CO3.
Methanol provided the desired products at a higher conversion (Table 1, entries 1-6).The corresponding benzoate esters were produced by ethanol, isopropanol, butanol, octanol, and 2-octanol under visible light irradiation.The nucleophilicity between the secondary alcohol and the long chain carbon alcohol was weak; however, aldehyde conversions were below 10% in all cases when the reactions were performed in the dark (Table 1).Different substituted benzaldehydes were transformed to the corresponding esters under the same conditions (Table 1, entries 7-12).Aldehyde conversions of 95.5% and 99.4% were reached (Table 1, entries 7 and 8).The substituted benzaldehyde conversions with an electron-withdrawing group reached only 66.2% and 48.6% (Table 1, entries 9 and 10).In contrast, the substituted benzaldehydes with electron-donating groups proved more advantageous for the esterification reaction than those with electron-withdrawing groups.The more stable the radical resonance structure, the higher was the reactant conversion.In contrast, when electron-withdrawing groups were located at the counter point of the benzene ring, free radical resonance structures were formed that were unstable and disadvantageous for the esterification reaction.Even reactive hetero-cycles with a long-chain aliphatic aldehyde, such as furfuraldehyde or valeraldehyde, could be transformed into the corresponding esters with modest conversions (52.6% and 40.1%,Table 1, entries 11 and 12).Both electron-withdrawing and electron-donating benzylic aldehydes worked for this transformation using silver photo-catalysts.choosing 8 mL of methanol as a solvent, 1.0 mmol of benzaldehyde as a reactant, and 30 mg of catalyst under advantageous conditions such as 35 ± 3 °C, an Ar atmosphere, and normal atmospheric pressure.
The reactions of benzaldehyde with different alcohols were investigated by using 71 wt% Ag3PO4/Ag/Bi2O2CO3.
Methanol provided the desired products at a higher conversion (Table 1, entries 1-6).The corresponding benzoate esters were produced by ethanol, isopropanol, butanol, octanol, and 2-octanol under visible light irradiation.The nucleophilicity between the secondary alcohol and the long chain carbon alcohol was weak; however, aldehyde conversions were below 10% in all cases when the reactions were performed in the dark (Table 1).Different substituted benzaldehydes were transformed to the corresponding esters under the same conditions (Table 1, entries 7-12).Aldehyde conversions of 95.5% and 99.4% were reached (Table 1, entries 7 and 8).The substituted benzaldehyde conversions with an electron-withdrawing group reached only 66.2% and 48.6% (Table 1, entries 9 and 10).In contrast, the substituted benzaldehydes with electron-donating groups proved more advantageous for the esterification reaction than those with electron-withdrawing groups.The more stable the radical resonance structure, the higher was the reactant conversion.In contrast, when electron-withdrawing groups were located at the counter point of the benzene ring, free radical resonance structures were formed that were unstable and disadvantageous for the esterification reaction.Even reactive hetero-cycles with a long-chain aliphatic aldehyde, such as furfuraldehyde or valeraldehyde, could be transformed into the corresponding esters with modest conversions (52.6% and 40.1%,Table 1, entries 11 and 12).Both electron-withdrawing and electron-donating benzylic aldehydes worked for this transformation using silver photo-catalysts.choosing 8 mL of methanol as a solvent, 1.0 mmol of benzaldehyde as a reactant, and 30 mg of catalyst under advantageous conditions such as 35 ± 3 °C, an Ar atmosphere, and normal atmospheric pressure.
The reactions of benzaldehyde with different alcohols were investigated by using 71 wt% Ag3PO4/Ag/Bi2O2CO3.
Methanol provided the desired products at a higher conversion (Table 1, entries 1-6).The corresponding benzoate esters were produced by ethanol, isopropanol, butanol, octanol, and 2-octanol under visible light irradiation.The nucleophilicity between the secondary alcohol and the long chain carbon alcohol was weak; however, aldehyde conversions were below 10% in all cases when the reactions were performed in the dark (Table 1).Different substituted benzaldehydes were transformed to the corresponding esters under the same conditions (Table 1, entries 7-12).Aldehyde conversions of 95.5% and 99.4% were reached (Table 1, entries 7 and 8).The substituted benzaldehyde conversions with an electron-withdrawing group reached only 66.2% and 48.6% (Table 1, entries 9 and 10).In contrast, the substituted benzaldehydes with electron-donating groups proved more advantageous for the esterification reaction than those with electron-withdrawing groups.The more stable the radical resonance structure, the higher was the reactant conversion.In contrast, when electron-withdrawing groups were located at the counter point of the benzene ring, free radical resonance structures were formed that were unstable and disadvantageous for the esterification reaction.Even reactive hetero-cycles with a long-chain aliphatic aldehyde, such as furfuraldehyde or valeraldehyde, could be transformed into the corresponding esters with modest conversions (52.6% and 40.1%,Table 1, entries 11 and 12).Both electron-withdrawing and electron-donating benzylic aldehydes worked for this transformation using silver photo-catalysts.choosing 8 mL of methanol as a solvent, 1.0 mmol of benzaldehyde as a reactant, and 30 mg of catalyst under advantageous conditions such as 35 ± 3 °C, an Ar atmosphere, and normal atmospheric pressure.
The reactions of benzaldehyde with different alcohols were investigated by using 71 wt% Ag3PO4/Ag/Bi2O2CO3.Methanol provided the desired products at a higher conversion (Table 1, entries 1-6).The corresponding benzoate esters were produced by ethanol, isopropanol, butanol, octanol, and 2-octanol under visible light irradiation.The nucleophilicity between the secondary alcohol and the long chain carbon alcohol was weak; however, aldehyde conversions were below 10% in all cases when the reactions were performed in the dark (Table 1).Different substituted benzaldehydes were transformed to the corresponding esters under the same conditions (Table 1, entries 7-12).Aldehyde conversions of 95.5% and 99.4% were reached (Table 1, entries 7 and 8).The substituted benzaldehyde conversions with an electron-withdrawing group reached only 66.2% and 48.6% (Table 1, entries 9 and 10).In contrast, the substituted benzaldehydes with electron-donating groups proved more advantageous for the esterification reaction than those with electron-withdrawing groups.The more stable the radical resonance structure, the higher was the reactant conversion.In contrast, when electron-withdrawing groups were located at the counter point of the benzene ring, free radical resonance structures were formed that were unstable and disadvantageous for the esterification reaction.Even reactive hetero-cycles with a long-chain aliphatic aldehyde, such as furfuraldehyde or valeraldehyde, could be transformed into the corresponding esters with modest conversions (52.6% and 40.1%,Table 1, entries 11 and 12).Both electron-withdrawing and electron-donating benzylic aldehydes worked for this transformation using silver photo-catalysts.Reaction conditions: aldehyde (1.0 mmol) and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to alcohol (8 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 choosing 8 mL of methanol as a solvent, 1.0 mmol of benzaldehyde as a reactant, and 30 mg of catalyst under advantageous conditions such as 35 ± 3 °C, an Ar atmosphere, and normal atmospheric pressure.
The reactions of benzaldehyde with different alcohols were investigated by using 71 wt% Ag3PO4/Ag/Bi2O2CO3.Methanol provided the desired products at a higher conversion (Table 1, entries 1-6).The corresponding benzoate esters were produced by ethanol, isopropanol, butanol, octanol, and 2-octanol under visible light irradiation.The nucleophilicity between the secondary alcohol and the long chain carbon alcohol was weak; however, aldehyde conversions were below 10% in all cases when the reactions were performed in the dark (Table 1).Different substituted benzaldehydes were transformed to the corresponding esters under the same conditions (Table 1, entries 7-12).Aldehyde conversions of 95.5% and 99.4% were reached (Table 1, entries 7 and 8).The substituted benzaldehyde conversions with an electron-withdrawing group reached only 66.2% and 48.6% (Table 1, entries 9 and 10).In contrast, the substituted benzaldehydes with electron-donating groups proved more advantageous for the esterification reaction than those with electron-withdrawing groups.The more stable the radical resonance structure, the higher was the reactant conversion.In contrast, when electron-withdrawing groups were located at the counter point of the benzene ring, free radical resonance structures were formed that were unstable and disadvantageous for the esterification reaction.Even reactive hetero-cycles with a long-chain aliphatic aldehyde, such as furfuraldehyde or valeraldehyde, could be transformed into the corresponding esters with modest conversions (52.6% and 40.1%,Table 1, entries 11 and 12).Both electron-withdrawing and electron-donating benzylic aldehydes worked for this transformation using silver photo-catalysts.Reaction conditions: aldehyde (1.0 mmol) and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to alcohol (8 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 choosing 8 mL of methanol as a solvent, 1.0 mmol of benzaldehyde as a reactant, and 30 mg of catalyst under advantageous conditions such as 35 ± 3 °C, an Ar atmosphere, and normal atmospheric pressure.
The reactions of benzaldehyde with different alcohols were investigated by using 71 wt% Ag3PO4/Ag/Bi2O2CO3.Methanol provided the desired products at a higher conversion (Table 1, entries 1-6).The corresponding benzoate esters were produced by ethanol, isopropanol, butanol, octanol, and 2-octanol under visible light irradiation.The nucleophilicity between the secondary alcohol and the long chain carbon alcohol was weak; however, aldehyde conversions were below 10% in all cases when the reactions were performed in the dark (Table 1).Different substituted benzaldehydes were transformed to the corresponding esters under the same conditions (Table 1, entries 7-12).Aldehyde conversions of 95.5% and 99.4% were reached (Table 1, entries 7 and 8).The substituted benzaldehyde conversions with an electron-withdrawing group reached only 66.2% and 48.6% (Table 1, entries 9 and 10).In contrast, the substituted benzaldehydes with electron-donating groups proved more advantageous for the esterification reaction than those with electron-withdrawing groups.The more stable the radical resonance structure, the higher was the reactant conversion.In contrast, when electron-withdrawing groups were located at the counter point of the benzene ring, free radical resonance structures were formed that were unstable and disadvantageous for the esterification reaction.Even reactive hetero-cycles with a long-chain aliphatic aldehyde, such as furfuraldehyde or valeraldehyde, could be transformed into the corresponding esters with modest conversions (52.6% and 40.1%,Table 1, entries 11 and 12).Both electron-withdrawing and electron-donating benzylic aldehydes worked for this transformation using silver photo-catalysts.Reaction conditions: aldehyde (1.0 mmol) and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to alcohol (8 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 choosing 8 mL of methanol as a solvent, 1.0 mmol of benzaldehyde as a reactant, and 30 mg of catalyst under advantageous conditions such as 35 ± 3 °C, an Ar atmosphere, and normal atmospheric pressure.
The reactions of benzaldehyde with different alcohols were investigated by using 71 wt% Ag3PO4/Ag/Bi2O2CO3.Methanol provided the desired products at a higher conversion (Table 1, entries 1-6).The corresponding benzoate esters were produced by ethanol, isopropanol, butanol, octanol, and 2-octanol under visible light irradiation.The nucleophilicity between the secondary alcohol and the long chain carbon alcohol was weak; however, aldehyde conversions were below 10% in all cases when the reactions were performed in the dark (Table 1).Different substituted benzaldehydes were transformed to the corresponding esters under the same conditions (Table 1, entries 7-12).Aldehyde conversions of 95.5% and 99.4% were reached (Table 1, entries 7 and 8).The substituted benzaldehyde conversions with an electron-withdrawing group reached only 66.2% and 48.6% (Table 1, entries 9 and 10).In contrast, the substituted benzaldehydes with electron-donating groups proved more advantageous for the esterification reaction than those with electron-withdrawing groups.The more stable the radical resonance structure, the higher was the reactant conversion.In contrast, when electron-withdrawing groups were located at the counter point of the benzene ring, free radical resonance structures were formed that were unstable and disadvantageous for the esterification reaction.Even reactive hetero-cycles with a long-chain aliphatic aldehyde, such as furfuraldehyde or valeraldehyde, could be transformed into the corresponding esters with modest conversions (52.6% and 40.1%,Table 1, entries 11 and 12).Both electron-withdrawing and electron-donating benzylic aldehydes worked for this transformation using silver photo-catalysts.Reaction conditions: aldehyde (1.0 mmol) and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to alcohol (8 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 choosing 8 mL of methanol as a solvent, 1.0 mmol of benzaldehyde as a reactant, and 30 mg of catalyst under advantageous conditions such as 35 ± 3 °C, an Ar atmosphere, and normal atmospheric pressure.
The reactions of benzaldehyde with different alcohols were investigated by using 71 wt% Ag3PO4/Ag/Bi2O2CO3.Methanol provided the desired products at a higher conversion (Table 1, entries 1-6).The corresponding benzoate esters were produced by ethanol, isopropanol, butanol, octanol, and 2-octanol under visible light irradiation.The nucleophilicity between the secondary alcohol and the long chain carbon alcohol was weak; however, aldehyde conversions were below 10% in all cases when the reactions were performed in the dark (Table 1).Different substituted benzaldehydes were transformed to the corresponding esters under the same conditions (Table 1, entries 7-12).Aldehyde conversions of 95.5% and 99.4% were reached (Table 1, entries 7 and 8).The substituted benzaldehyde conversions with an electron-withdrawing group reached only 66.2% and 48.6% (Table 1, entries 9 and 10).In contrast, the substituted benzaldehydes with electron-donating groups proved more advantageous for the esterification reaction than those with electron-withdrawing groups.The more stable the radical resonance structure, the higher was the reactant conversion.In contrast, when electron-withdrawing groups were located at the counter point of the benzene ring, free radical resonance structures were formed that were unstable and disadvantageous for the esterification reaction.Even reactive hetero-cycles with a long-chain aliphatic aldehyde, such as furfuraldehyde or valeraldehyde, could be transformed into the corresponding esters with modest conversions (52.6% and 40.1%,Table 1, entries 11 and 12).Both electron-withdrawing and electron-donating benzylic aldehydes worked for this transformation using silver photo-catalysts.Reaction conditions: aldehyde (1.0 mmol) and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to alcohol (8 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 choosing 8 mL of methanol as a solvent, 1.0 mmol of benzaldehyde as a reactant, and 30 mg of catalyst under advantageous conditions such as 35 ± 3 °C, an Ar atmosphere, and normal atmospheric pressure. The reactions of benzaldehyde with different alcohols were investigated by using 71 wt% Ag3PO4/Ag/Bi2O2CO3.Methanol provided the desired products at a higher conversion (Table 1, entries 1-6).The corresponding benzoate esters were produced by ethanol, isopropanol, butanol, octanol, and 2-octanol under visible light irradiation.The nucleophilicity between the secondary alcohol and the long chain carbon alcohol was weak; however, aldehyde conversions were below 10% in all cases when the reactions were performed in the dark (Table 1).Different substituted benzaldehydes were transformed to the corresponding esters under the same conditions (Table 1, entries 7-12).Aldehyde conversions of 95.5% and 99.4% were reached (Table 1, entries 7 and 8).The substituted benzaldehyde conversions with an electron-withdrawing group reached only 66.2% and 48.6% (Table 1, entries 9 and 10).In contrast, the substituted benzaldehydes with electron-donating groups proved more advantageous for the esterification reaction than those with electron-withdrawing groups.The more stable the radical resonance structure, the higher was the reactant conversion.In contrast, when electron-withdrawing groups were located at the counter point of the benzene ring, free radical resonance structures were formed that were unstable and disadvantageous for the esterification reaction.Even reactive hetero-cycles with a long-chain aliphatic aldehyde, such as furfuraldehyde or valeraldehyde, could be transformed into the corresponding esters with modest conversions (52.6% and 40.1%,Table 1, entries 11 and 12).Both electron-withdrawing and electron-donating benzylic aldehydes worked for this transformation using silver photo-catalysts.Subsequently, the effects of the different photo-catalysts and the Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 with different Ag 3 PO 4 mass ratios were tested (Table 2).After 24 h of visible light irradiation, low conversions were detected with the Bi 2 O 2 CO 3 support compared with the other metal or metal oxide-loaded photo-catalysts (Table 2, entries 1-3).This observation confirmed that the metal or metal oxide nanoparticles were crucial for the esterification reaction.The photocatalytic esterification of benzaldehyde and methanol was carried out using the Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 composites with varied silver phosphate contents (Table 2, entries 4-8).The conversion increased and then decreased with the increasing silver phosphate content.The highest conversion (88.3%) for the esterification of benzaldehyde and methanol was obtained using the 71 wt % Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 composite (Table 2, entry 7).Moreover, the conversion conducted in the dark was significantly lower than that under visible light irradiation.Therefore, light was crucial for the reaction process (Table 2, entries 1-8).Subsequently, the effects of the different photo-catalysts and the Ag3PO4/Ag/Bi2O2CO3 with different Ag3PO4 mass ratios were tested (Table 2).After 24 h of visible light irradiation, low conversions were detected with the Bi2O2CO3 support compared with the other metal or metal oxide-loaded photo-catalysts (Table 2, entries 1-3).This observation confirmed that the metal or metal oxide nanoparticles were crucial for the esterification reaction.The photocatalytic esterification of benzaldehyde and methanol was carried out using the Ag3PO4/Ag/Bi2O2CO3 composites with varied silver phosphate contents (Table 2, entries 4-8).The conversion increased and then decreased with the increasing silver phosphate content.The highest conversion (88.3%) for the esterification of benzaldehyde and methanol was obtained using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 composite (Table 2, entry 7).Moreover, the conversion conducted in the dark was significantly lower than that under visible light irradiation.Therefore, light was crucial for the reaction process (Table 2, entries 1-8).Reaction conditions: aldehyde (1.0 mmol) and catalyst (30 mg) were added to alcohol (8 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10−2 W•cm −2 ) as the visible light source under an Ar atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Esterification of Alcohols and Alcohols
The catalytic activities of different proportions of Ag3PO4 in Ag3PO4/Ag/Bi2O2CO3 were tested in the esterification reaction of benzaldehyde and methanol where the 71 wt% Ag3PO4/Ag/Bi2O2CO3 had an excellent catalytic outcome.Therefore, the esterification reactions of alcohols and alcohols were conducted using 71 wt% Ag3PO4/Ag/Bi2O2CO3 as a catalyst.Benzyl alcohol (1.0 mmol) and methanol (8 mL) were applied in this reaction, which was tested with various bases, different dosages of the base, and different alcohol substitutes and the bases showed a great influence on the reaction.The conversion was highest using Cs2CO3 as a base (Table S2, entries 1-5).Finally, the optimized amount of base was 0.6 mmol (Table S2, entries 1, 6-8).
Under the optimized reaction conditions, various fatty alcohols and benzyl alcohol derivatives were rapidly converted to the corresponding esters (Table 3).
Reaction conditions: derivative of benzyl alcohol (1.0 mmol), base (0.6 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to the fatty alcohol derivatives (8 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 Reaction conditions: aldehyde (1.0 mmol) and catalyst (30 mg) were added to alcohol (8 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10−2 W•cm −2 ) as the visible light source under an Ar atmosphere at 35 ± 3 • C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Esterification of Alcohols and Alcohols
The catalytic activities of different proportions of Ag 3 PO 4 in Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 were tested in the esterification reaction of benzaldehyde and methanol where the 71 wt % Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 had an excellent catalytic outcome.Therefore, the esterification reactions of alcohols and alcohols were conducted using 71 wt % Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 as a catalyst.Benzyl alcohol (1.0 mmol) and methanol (8 mL) were applied in this reaction, which was tested with various bases, different dosages of the base, and different alcohol substitutes and the bases showed a great influence on the reaction.The conversion was highest using Cs 2 CO 3 as a base (Table S2, entries 1-5).Finally, the optimized amount of base was 0.6 mmol (Table S2, entries 1, 6-8).
Under the optimized reaction conditions, various fatty alcohols and benzyl alcohol derivatives were rapidly converted to the corresponding esters (Table 3).
Reaction conditions: derivative of benzyl alcohol (1.0 mmol), base (0.6 mmol Cs 2 CO 3 ), and Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 catalyst (30 mg) were added to the fatty alcohol derivatives (8 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 • C.After running for 24 h, the reaction conversion and selectivity were determined by GC. under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Amination of Alcohols and Amines
The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC. under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Amination of Alcohols and Amines
The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC. under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Amination of Alcohols and Amines
The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC. under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Amination of Alcohols and Amines
The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC. under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Amination of Alcohols and Amines
The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC. under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Amination of Alcohols and Amines
The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC. under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Amination of Alcohols and Amines
The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC. under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Amination of Alcohols and Amines
The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC. under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Amination of Alcohols and Amines
The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC. under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Amination of Alcohols and Amines
The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC. under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Amination of Alcohols and Amines
The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC. under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Amination of Alcohols and Amines
The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Amination of Alcohols and Amines
The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt % Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs 2 CO 3 as a base (Table S3, entries 1-5).With Cs 2 CO 3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs 2 CO 3 ), and Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 • C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Effect of Light Intensity and Wavelength
To certify that the reaction was photo-catalytic and that the light intensity and wavelength had an important influence on the reaction process [55,56], experiments were performed using different light intensities and wavelengths (Figures 5 and 6).The contributions of light irradiation were determined by subtracting the conversion in the dark from the overall conversion under light irradiation, equalizing both reactions at the same reaction temperature.Here, the conversion in the dark was seen as the contribution of the thermal effect.First, the conversion of benzaldehyde increased gradually with the increase in light intensity (Figure 5), whereas the conversion of benzaldehyde changed little in the dark, which indicated that the reaction was activated by light.Typically, when the light intensity was 0.01 W•cm −2 , the overall conversion was 64.9%, of which the light contribution to the overall process was 87%, while the thermal contribution accounted for only 13% at 35 ± 3 °C.More importantly, when the light intensity was increased from 0.01 W•cm −2 to 0.043 W•cm −2 , the conversion of reactants increased dramatically from 64.9% to 96.8%.This result further demonstrated that the light intensity played a significant role in the reaction process.When the light intensity was stronger, more energy was provided, and more electrons and holes were produced by Ag3PO4 and Bi2O2CO3.The faster the transfer rate of the electrons and holes, the more prominent was the light contribution to the conversion of benzaldehyde.
The effects of different wavelength ranges on the esterification reaction of aldehydes and alcohols are shown in Figure 6.First, the wider the wavelength range, the higher was the conversion of benzaldehyde.In other words, when the wavelength range was changed from 400-800 nm to 650-800 nm, the conversion of benzaldehyde was reduced.For example, the conversion of benzaldehyde was 85.7%, when the wavelength range was between 400 and 800 nm.However, the conversion was 78.3%, when the wavelength range was monitored between 450 and 800 nm.The conversion was only 20.5%, when the wavelength range was restricted between 650 and 800 nm with equal irradiation intensity.In addition, the reaction conversion was 8.5% in the dark at the same temperature.A minor change occurred with wavelengths longer than 650 nm or shorter than 450 nm; 91% of the total benzaldehyde conversion was obtained by the contribution of visible light irradiation between 400 and 800 nm, while the thermal contribution accounted for the other 9%.under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Amination of Alcohols and Amines
The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Effect of Light Intensity and Wavelength
To certify that the reaction was photo-catalytic and that the light intensity and wavelength had an important influence on the reaction process [55,56], experiments were performed using different light intensities and wavelengths (Figures 5 and 6).The contributions of light irradiation were determined by subtracting the conversion in the dark from the overall conversion under light irradiation, equalizing both reactions at the same reaction temperature.Here, the conversion in the dark was seen as the contribution of the thermal effect.First, the conversion of benzaldehyde increased gradually with the increase in light intensity (Figure 5), whereas the conversion of benzaldehyde changed little in the dark, which indicated that the reaction was activated by light.Typically, when the light intensity was 0.01 W•cm −2 , the overall conversion was 64.9%, of which the light contribution to the overall process was 87%, while the thermal contribution accounted for only 13% at 35 ± 3 °C.More importantly, when the light intensity was increased from 0.01 W•cm −2 to 0.043 W•cm −2 , the conversion of reactants increased dramatically from 64.9% to 96.8%.This result further demonstrated that the light intensity played a significant role in the reaction process.When the light intensity was stronger, more energy was provided, and more electrons and holes were produced by Ag3PO4 and Bi2O2CO3.The faster the transfer rate of the electrons and holes, the more prominent was the light contribution to the conversion of benzaldehyde.
The effects of different wavelength ranges on the esterification reaction of aldehydes and alcohols are shown in Figure 6.First, the wider the wavelength range, the higher was the conversion of benzaldehyde.In other words, when the wavelength range was changed from 400-800 nm to 650-800 nm, the conversion of benzaldehyde was reduced.For example, the conversion of benzaldehyde was 85.7%, when the wavelength range was between 400 and 800 nm.However, the conversion was 78.3%, when the wavelength range was monitored between 450 and 800 nm.The conversion was only 20.5%, when the wavelength range was restricted between 650 and 800 nm with equal irradiation intensity.In addition, the reaction conversion was 8.5% in the dark at the same temperature.A minor change occurred with wavelengths longer than 650 nm or shorter than 450 nm; 91% of the total benzaldehyde conversion was obtained by the contribution of visible light irradiation between 400 and 800 nm, while the thermal contribution accounted for the other 9%.under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Amination of Alcohols and Amines
The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Effect of Light Intensity and Wavelength
To certify that the reaction was photo-catalytic and that the light intensity and wavelength had an important influence on the reaction process [55,56], experiments were performed using different light intensities and wavelengths (Figures 5 and 6).The contributions of light irradiation were determined by subtracting the conversion in the dark from the overall conversion under light irradiation, equalizing both reactions at the same reaction temperature.Here, the conversion in the dark was seen as the contribution of the thermal effect.First, the conversion of benzaldehyde increased gradually with the increase in light intensity (Figure 5), whereas the conversion of benzaldehyde changed little in the dark, which indicated that the reaction was activated by light.Typically, when the light intensity was 0.01 W•cm −2 , the overall conversion was 64.9%, of which the light contribution to the overall process was 87%, while the thermal contribution accounted for only 13% at 35 ± 3 °C.More importantly, when the light intensity was increased from 0.01 W•cm −2 to 0.043 W•cm −2 , the conversion of reactants increased dramatically from 64.9% to 96.8%.This result further demonstrated that the light intensity played a significant role in the reaction process.When the light intensity was stronger, more energy was provided, and more electrons and holes were produced by Ag3PO4 and Bi2O2CO3.The faster the transfer rate of the electrons and holes, the more prominent was the light contribution to the conversion of benzaldehyde.
The effects of different wavelength ranges on the esterification reaction of aldehydes and alcohols are shown in Figure 6.First, the wider the wavelength range, the higher was the conversion of benzaldehyde.In other words, when the wavelength range was changed from 400-800 nm to 650-800 nm, the conversion of benzaldehyde was reduced.For example, the conversion of benzaldehyde was 85.7%, when the wavelength range was between 400 and 800 nm.However, the conversion was 78.3%, when the wavelength range was monitored between 450 and 800 nm.The conversion was only 20.5%, when the wavelength range was restricted between 650 and 800 nm with equal irradiation intensity.In addition, the reaction conversion was 8.5% in the dark at the same temperature.A minor change occurred with wavelengths longer than 650 nm or shorter than 450 nm; 91% of the total benzaldehyde conversion was obtained by the contribution of visible light irradiation between 400 and 800 nm, while the thermal contribution accounted for the other 9%.under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Amination of Alcohols and Amines
The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Effect of Light Intensity and Wavelength
To certify that the reaction was photo-catalytic and that the light intensity and wavelength had an important influence on the reaction process [55,56], experiments were performed using different light intensities and wavelengths (Figures 5 and 6).The contributions of light irradiation were determined by subtracting the conversion in the dark from the overall conversion under light irradiation, equalizing both reactions at the same reaction temperature.Here, the conversion in the dark was seen as the contribution of the thermal effect.First, the conversion of benzaldehyde increased gradually with the increase in light intensity (Figure 5), whereas the conversion of benzaldehyde changed little in the dark, which indicated that the reaction was activated by light.Typically, when the light intensity was 0.01 W•cm −2 , the overall conversion was 64.9%, of which the light contribution to the overall process was 87%, while the thermal contribution accounted for only 13% at 35 ± 3 °C.More importantly, when the light intensity was increased from 0.01 W•cm −2 to 0.043 W•cm −2 , the conversion of reactants increased dramatically from 64.9% to 96.8%.This result further demonstrated that the light intensity played a significant role in the reaction process.When the light intensity was stronger, more energy was provided, and more electrons and holes were produced by Ag3PO4 and Bi2O2CO3.The faster the transfer rate of the electrons and holes, the more prominent was the light contribution to the conversion of benzaldehyde.
The effects of different wavelength ranges on the esterification reaction of aldehydes and alcohols are shown in Figure 6.First, the wider the wavelength range, the higher was the conversion of benzaldehyde.In other words, when the wavelength range was changed from 400-800 nm to 650-800 nm, the conversion of benzaldehyde was reduced.For example, the conversion of benzaldehyde was 85.7%, when the wavelength range was between 400 and 800 nm.However, the conversion was 78.3%, when the wavelength range was monitored between 450 and 800 nm.The conversion was only 20.5%, when the wavelength range was restricted between 650 and 800 nm with equal irradiation intensity.In addition, the reaction conversion was 8.5% in the dark at the same temperature.A minor change occurred with wavelengths longer than 650 nm or shorter than 450 nm; 91% of the total benzaldehyde conversion was obtained by the contribution of visible light irradiation between 400 and 800 nm, while the thermal contribution accounted for the other 9%.under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Amination of Alcohols and Amines
The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Effect of Light Intensity and Wavelength
To certify that the reaction was photo-catalytic and that the light intensity and wavelength had an important influence on the reaction process [55,56], experiments were performed using different light intensities and wavelengths (Figures 5 and 6).The contributions of light irradiation were determined by subtracting the conversion in the dark from the overall conversion under light irradiation, equalizing both reactions at the same reaction temperature.Here, the conversion in the dark was seen as the contribution of the thermal effect.First, the conversion of benzaldehyde increased gradually with the increase in light intensity (Figure 5), whereas the conversion of benzaldehyde changed little in the dark, which indicated that the reaction was activated by light.Typically, when the light intensity was 0.01 W•cm −2 , the overall conversion was 64.9%, of which the light contribution to the overall process was 87%, while the thermal contribution accounted for only 13% at 35 ± 3 °C.More importantly, when the light intensity was increased from 0.01 W•cm −2 to 0.043 W•cm −2 , the conversion of reactants increased dramatically from 64.9% to 96.8%.This result further demonstrated that the light intensity played a significant role in the reaction process.When the light intensity was stronger, more energy was provided, and more electrons and holes were produced by Ag3PO4 and Bi2O2CO3.The faster the transfer rate of the electrons and holes, the more prominent was the light contribution to the conversion of benzaldehyde.
The effects of different wavelength ranges on the esterification reaction of aldehydes and alcohols are shown in Figure 6.First, the wider the wavelength range, the higher was the conversion of benzaldehyde.In other words, when the wavelength range was changed from 400-800 nm to 650-800 nm, the conversion of benzaldehyde was reduced.For example, the conversion of benzaldehyde was 85.7%, when the wavelength range was between 400 and 800 nm.However, the conversion was 78.3%, when the wavelength range was monitored between 450 and 800 nm.The conversion was only 20.5%, when the wavelength range was restricted between 650 and 800 nm with equal irradiation intensity.In addition, the reaction conversion was 8.5% in the dark at the same temperature.A minor change occurred with wavelengths longer than 650 nm or shorter than 450 nm; 91% of the total benzaldehyde conversion was obtained by the contribution of visible light irradiation between 400 and 800 nm, while the thermal contribution accounted for the other 9%.under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Amination of Alcohols and Amines
The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Effect of Light Intensity and Wavelength
To certify that the reaction was photo-catalytic and that the light intensity and wavelength had an important influence on the reaction process [55,56], experiments were performed using different light intensities and wavelengths (Figures 5 and 6).The contributions of light irradiation were determined by subtracting the conversion in the dark from the overall conversion under light irradiation, equalizing both reactions at the same reaction temperature.Here, the conversion in the dark was seen as the contribution of the thermal effect.First, the conversion of benzaldehyde increased gradually with the increase in light intensity (Figure 5), whereas the conversion of benzaldehyde changed little in the dark, which indicated that the reaction was activated by light.Typically, when the light intensity was 0.01 W•cm −2 , the overall conversion was 64.9%, of which the light contribution to the overall process was 87%, while the thermal contribution accounted for only 13% at 35 ± 3 °C.More importantly, when the light intensity was increased from 0.01 W•cm −2 to 0.043 W•cm −2 , the conversion of reactants increased dramatically from 64.9% to 96.8%.This result further demonstrated that the light intensity played a significant role in the reaction process.When the light intensity was stronger, more energy was provided, and more electrons and holes were produced by Ag3PO4 and Bi2O2CO3.The faster the transfer rate of the electrons and holes, the more prominent was the light contribution to the conversion of benzaldehyde.
The effects of different wavelength ranges on the esterification reaction of aldehydes and alcohols are shown in Figure 6.First, the wider the wavelength range, the higher was the conversion of benzaldehyde.In other words, when the wavelength range was changed from 400-800 nm to 650-800 nm, the conversion of benzaldehyde was reduced.For example, the conversion of benzaldehyde was 85.7%, when the wavelength range was between 400 and 800 nm.However, the conversion was 78.3%, when the wavelength range was monitored between 450 and 800 nm.The conversion was only 20.5%, when the wavelength range was restricted between 650 and 800 nm with equal irradiation intensity.In addition, the reaction conversion was 8.5% in the dark at the same temperature.A minor change occurred with wavelengths longer than 650 nm or shorter than 450 nm; 91% of the total benzaldehyde conversion was obtained by the contribution of visible light irradiation between 400 and 800 nm, while the thermal contribution accounted for the other 9%.under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Amination of Alcohols and Amines
The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Effect of Light Intensity and Wavelength
To certify that the reaction was photo-catalytic and that the light intensity and wavelength had an important influence on the reaction process [55,56], experiments were performed using different light intensities and wavelengths (Figures 5 and 6).The contributions of light irradiation were determined by subtracting the conversion in the dark from the overall conversion under light irradiation, equalizing both reactions at the same reaction temperature.Here, the conversion in the dark was seen as the contribution of the thermal effect.First, the conversion of benzaldehyde increased gradually with the increase in light intensity (Figure 5), whereas the conversion of benzaldehyde changed little in the dark, which indicated that the reaction was activated by light.Typically, when the light intensity was 0.01 W•cm −2 , the overall conversion was 64.9%, of which the light contribution to the overall process was 87%, while the thermal contribution accounted for only 13% at 35 ± 3 °C.More importantly, when the light intensity was increased from 0.01 W•cm −2 to 0.043 W•cm −2 , the conversion of reactants increased dramatically from 64.9% to 96.8%.This result further demonstrated that the light intensity played a significant role in the reaction process.When the light intensity was stronger, more energy was provided, and more electrons and holes were produced by Ag3PO4 and Bi2O2CO3.The faster the transfer rate of the electrons and holes, the more prominent was the light contribution to the conversion of benzaldehyde.
The effects of different wavelength ranges on the esterification reaction of aldehydes and alcohols are shown in Figure 6.First, the wider the wavelength range, the higher was the conversion of benzaldehyde.In other words, when the wavelength range was changed from 400-800 nm to 650-800 nm, the conversion of benzaldehyde was reduced.For example, the conversion of benzaldehyde was 85.7%, when the wavelength range was between 400 and 800 nm.However, the conversion was 78.3%, when the wavelength range was monitored between 450 and 800 nm.The conversion was only 20.5%, when the wavelength range was restricted between 650 and 800 nm with equal irradiation intensity.In addition, the reaction conversion was 8.5% in the dark at the same temperature.A minor change occurred with wavelengths longer than 650 nm or shorter than 450 nm; 91% of the total benzaldehyde conversion was obtained by the contribution of visible light irradiation between 400 and 800 nm, while the thermal contribution accounted for the other 9%.under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, [12][13][14]. Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Effect of Light Intensity and Wavelength
To certify that the reaction was photo-catalytic and that the light intensity and wavelength had an important influence on the reaction process [55,56], experiments were performed using different light intensities and wavelengths (Figures 5 and 6).The contributions of light irradiation were determined by subtracting the conversion in the dark from the overall conversion under light irradiation, equalizing both reactions at the same reaction temperature.Here, the conversion in the dark was seen as the contribution of the thermal effect.First, the conversion of benzaldehyde increased gradually with the increase in light intensity (Figure 5), whereas the conversion of benzaldehyde changed little in the dark, which indicated that the reaction was activated by light.Typically, when the light intensity was 0.01 W•cm −2 , the overall conversion was 64.9%, of which the light contribution to the overall process was 87%, while the thermal contribution accounted for only 13% at 35 ± 3 °C.More importantly, when the light intensity was increased from 0.01 W•cm −2 to 0.043 W•cm −2 , the conversion of reactants increased dramatically from 64.9% to 96.8%.This result further demonstrated that the light intensity played a significant role in the reaction process.When the light intensity was stronger, more energy was provided, and more electrons and holes were produced by Ag3PO4 and Bi2O2CO3.The faster the transfer rate of the electrons and holes, the more prominent was the light contribution to the conversion of benzaldehyde.
The effects of different wavelength ranges on the esterification reaction of aldehydes and alcohols are shown in Figure 6.First, the wider the wavelength range, the higher was the conversion of benzaldehyde.In other words, when the wavelength range was changed from 400-800 nm to 650-800 nm, the conversion of benzaldehyde was reduced.For example, the conversion of benzaldehyde was 85.7%, when the wavelength range was between 400 and 800 nm.However, the conversion was 78.3%, when the wavelength range was monitored between 450 and 800 nm.The conversion was only 20.5%, when the wavelength range was restricted between 650 and 800 nm with equal irradiation intensity.In addition, the reaction conversion was 8.5% in the dark at the same temperature.A minor change occurred with wavelengths longer than 650 nm or shorter than 450 nm; 91% of the total benzaldehyde conversion was obtained by the contribution of visible light irradiation between 400 and 800 nm, while the thermal contribution accounted for the other 9%.under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, [12][13][14]. Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Effect of Light Intensity and Wavelength
To certify that the reaction was photo-catalytic and that the light intensity and wavelength had an important influence on the reaction process [55,56], experiments were performed using different light intensities and wavelengths (Figures 5 and 6).The contributions of light irradiation were determined by subtracting the conversion in the dark from the overall conversion under light irradiation, equalizing both reactions at the same reaction temperature.Here, the conversion in the dark was seen as the contribution of the thermal effect.First, the conversion of benzaldehyde increased gradually with the increase in light intensity (Figure 5), whereas the conversion of benzaldehyde changed little in the dark, which indicated that the reaction was activated by light.Typically, when the light intensity was 0.01 W•cm −2 , the overall conversion was 64.9%, of which the light contribution to the overall process was 87%, while the thermal contribution accounted for only 13% at 35 ± 3 °C.More importantly, when the light intensity was increased from 0.01 W•cm −2 to 0.043 W•cm −2 , the conversion of reactants increased dramatically from 64.9% to 96.8%.This result further demonstrated that the light intensity played a significant role in the reaction process.When the light intensity was stronger, more energy was provided, and more electrons and holes were produced by Ag3PO4 and Bi2O2CO3.The faster the transfer rate of the electrons and holes, the more prominent was the light contribution to the conversion of benzaldehyde.
The effects of different wavelength ranges on the esterification reaction of aldehydes and alcohols are shown in Figure 6.First, the wider the wavelength range, the higher was the conversion of benzaldehyde.In other words, when the wavelength range was changed from 400-800 nm to 650-800 nm, the conversion of benzaldehyde was reduced.For example, the conversion of benzaldehyde was 85.7%, when the wavelength range was between 400 and 800 nm.However, the conversion was 78.3%, when the wavelength range was monitored between 450 and 800 nm.The conversion was only 20.5%, when the wavelength range was restricted between 650 and 800 nm with equal irradiation intensity.In addition, the reaction conversion was 8.5% in the dark at the same temperature.A minor change occurred with wavelengths longer than 650 nm or shorter than 450 nm; 91% of the total benzaldehyde conversion was obtained by the contribution of visible light irradiation between 400 and 800 nm, while the thermal contribution accounted for the other 9%.under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, [12][13][14]. Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Effect of Light Intensity and Wavelength
To certify that the reaction was photo-catalytic and that the light intensity and wavelength had an important influence on the reaction process [55,56], experiments were performed using different light intensities and wavelengths (Figures 5 and 6).The contributions of light irradiation were determined by subtracting the conversion in the dark from the overall conversion under light irradiation, equalizing both reactions at the same reaction temperature.Here, the conversion in the dark was seen as the contribution of the thermal effect.First, the conversion of benzaldehyde increased gradually with the increase in light intensity (Figure 5), whereas the conversion of benzaldehyde changed little in the dark, which indicated that the reaction was activated by light.Typically, when the light intensity was 0.01 W•cm −2 , the overall conversion was 64.9%, of which the light contribution to the overall process was 87%, while the thermal contribution accounted for only 13% at 35 ± 3 °C.More importantly, when the light intensity was increased from 0.01 W•cm −2 to 0.043 W•cm −2 , the conversion of reactants increased dramatically from 64.9% to 96.8%.This result further demonstrated that the light intensity played a significant role in the reaction process.When the light intensity was stronger, more energy was provided, and more electrons and holes were produced by Ag3PO4 and Bi2O2CO3.The faster the transfer rate of the electrons and holes, the more prominent was the light contribution to the conversion of benzaldehyde.
The effects of different wavelength ranges on the esterification reaction of aldehydes and alcohols are shown in Figure 6.First, the wider the wavelength range, the higher was the conversion of benzaldehyde.In other words, when the wavelength range was changed from 400-800 nm to 650-800 nm, the conversion of benzaldehyde was reduced.For example, the conversion of benzaldehyde was 85.7%, when the wavelength range was between 400 and 800 nm.However, the conversion was 78.3%, when the wavelength range was monitored between 450 and 800 nm.The conversion was only 20.5%, when the wavelength range was restricted between 650 and 800 nm with equal irradiation intensity.In addition, the reaction conversion was 8.5% in the dark at the same temperature.A minor change occurred with wavelengths longer than 650 nm or shorter than 450 nm; 91% of the total benzaldehyde conversion was obtained by the contribution of visible light under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Effect of Light Intensity and Wavelength
To certify that the reaction was photo-catalytic and that the light intensity and wavelength had an important influence on the reaction process [55,56], experiments were performed using different light intensities and wavelengths (Figures 5 and 6).The contributions of light irradiation were determined by subtracting the conversion in the dark from the overall conversion under light irradiation, equalizing both reactions at the same reaction temperature.Here, the conversion in the dark was seen as the contribution of the thermal effect.First, the conversion of benzaldehyde increased gradually with the increase in light intensity (Figure 5), whereas the conversion of benzaldehyde changed little in the dark, which indicated that the reaction was activated by light.Typically, when the light intensity was 0.01 W•cm −2 , the overall conversion was 64.9%, of which the light contribution to the overall process was 87%, while the thermal contribution accounted for only 13% at 35 ± 3 °C.More importantly, when the light intensity was increased from 0.01 W•cm −2 to 0.043 W•cm −2 , the conversion of reactants increased dramatically from 64.9% to 96.8%.This result further demonstrated that the light intensity played a significant role in the reaction process.When the light intensity was stronger, more energy was provided, and more electrons and holes were produced by Ag3PO4 and Bi2O2CO3.The faster the transfer rate of the electrons and holes, the more prominent was the light contribution to the conversion of benzaldehyde.
The effects of different wavelength ranges on the esterification reaction of aldehydes and alcohols are shown in Figure 6.First, the wider the wavelength range, the higher was the conversion of benzaldehyde.In other words, when the wavelength range was changed from 400-800 nm to 650-800 nm, the conversion of benzaldehyde was reduced.For example, the conversion of benzaldehyde was 85.7%, when the wavelength range was between 400 and 800 nm.However, the conversion was 78.3%, when the wavelength range was monitored between 450 and 800 nm.The conversion was only 20.5%, when the wavelength range was restricted between 650 and 800 nm with equal irradiation intensity.In addition, the reaction conversion was 8.5% in the dark at the same under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.The synthesis of imines by benzyl alcohol and aniline was studied using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalysts.The influences of solvents and bases were scrutinized to discover the optimal reaction conditions.The highest activity occurred when using Cs2CO3 as a base (Table S3, entries 1-5).With Cs2CO3 as the base, notable activity was achieved when benzotrifluoride was used as a solvent.The conversion of aniline did not even reach 40% in other solvents (Table S3, entries 6-11).Furthermore, the highest activity occurred when using 0.8 mmol of base (Table S3, entries 1, 12-14).
Different derivatives of alcohols and anilines were examined under the optimized conditions.Good conversions were produced except for p-methoxyaniline (Table 4, entries 1-5).In addition, 62.5% and 65.6% conversion were achieved with the allylic alcohols, such as cinnamyl alcohol and crotyl alcohol (Table 4, entries 9 and 11).Meanwhile, furfuryl alcohol was converted by using the catalyst (Table 4, entry 10).
Reaction conditions: alcohol (1.0 mmol), the substitute of aniline (0.5 mmol), base (0.8 mmol Cs2CO3), and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to benzotrifluoride (6 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an air atmosphere at 35 ± 3 °C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Effect of Light Intensity and Wavelength
To certify that the reaction was photo-catalytic and that the light intensity and wavelength had an important influence on the reaction process [55,56], experiments were performed using different light intensities and wavelengths (Figures 5 and 6).The contributions of light irradiation were determined by subtracting the conversion in the dark from the overall conversion under light irradiation, equalizing both reactions at the same reaction temperature.Here, the conversion in the dark was seen as the contribution of the thermal effect.First, the conversion of benzaldehyde increased gradually with the increase in light intensity (Figure 5), whereas the conversion of benzaldehyde changed little in the dark, which indicated that the reaction was activated by light.Typically, when the light intensity was 0.01 W•cm −2 , the overall conversion was 64.9%, of which the light contribution to the overall process was 87%, while the thermal contribution accounted for only 13% at 35 ± 3 °C.More importantly, when the light intensity was increased from 0.01 W•cm −2 to 0.043 W•cm −2 , the conversion of reactants increased dramatically from 64.9% to 96.8%.This result further demonstrated that the light intensity played a significant role in the reaction process.When the light intensity was stronger, more energy was provided, and more electrons and holes were produced by Ag3PO4 and Bi2O2CO3.The faster the transfer rate of the electrons and holes, the more prominent was the light contribution to the conversion of benzaldehyde.
The effects of different wavelength ranges on the esterification reaction of aldehydes and alcohols are shown in Figure 6.First, the wider the wavelength range, the higher was the conversion of benzaldehyde.In other words, when the wavelength range was changed from 400-800 nm to 650-800 nm, the conversion of benzaldehyde was reduced.For example, the conversion of benzaldehyde was 85.7%, when the wavelength range was between 400 and 800 nm.However, the conversion was 78.3%, when the wavelength range was monitored between 450 and 800 nm.The 65.6 >99 1.4 >99

Effect of Light Intensity and Wavelength
To certify that the reaction was photo-catalytic and that the light intensity and wavelength had an important influence on the reaction process [55,56], experiments were performed using different light intensities and wavelengths (Figures 5 and 6).The contributions of light irradiation were determined by subtracting the conversion in the dark from the overall conversion under light irradiation, equalizing both reactions at the same reaction temperature.Here, the conversion in the dark was seen as the contribution of the thermal effect.First, the conversion of benzaldehyde increased gradually with the increase in light intensity (Figure 5), whereas the conversion of benzaldehyde changed little in the dark, which indicated that the reaction was activated by light.Typically, when the light intensity was 0.01 W•cm −2 , the overall conversion was 64.9%, of which the light contribution to the overall process was 87%, while the thermal contribution accounted for only 13% at 35 ± 3 • C.More importantly, when the light intensity was increased from 0.01 W•cm −2 to 0.043 W•cm −2 , the conversion of reactants increased dramatically from 64.9% to 96.8%.This result further demonstrated that the light intensity played a significant role in the reaction process.When the light intensity was stronger, more energy was provided, and more electrons and holes were produced by Ag 3 PO 4 and Bi 2 O 2 CO 3 .The faster the transfer rate of the electrons and holes, the more prominent was the light contribution to the conversion of benzaldehyde.
The effects of different wavelength ranges on the esterification reaction of aldehydes and alcohols are shown in Figure 6.First, the wider the wavelength range, the higher was the conversion of benzaldehyde.In other words, when the wavelength range was changed from 400-800 nm to 650-800 nm, the conversion of benzaldehyde was reduced.For example, the conversion of benzaldehyde was 85.7%, when the wavelength range was between 400 and 800 nm.However, the conversion was 78.3%, when the wavelength range was monitored between 450 and 800 nm.The conversion was only 20.5%, when the wavelength range was restricted between 650 and 800 nm with equal irradiation intensity.In addition, the reaction conversion was 8.5% in the dark at the same temperature.A minor change occurred with wavelengths longer than 650 nm or shorter than irradiation between 400 and 800 nm, while the thermal contribution accounted for the other 9%.Using the same calculation method, the contribution of light to the conversion could be calculated in any wavelength range.As shown in Figure 6, when the wavelength range was between 400 and 650 nm, the contribution of light was 85%.The light contributions to the conversion of benzaldehyde between the wavelength ranges of 400-450, 450-510, 510-650, and 650-800 nm were 10%, 44%, 31%, and 15%, respectively.These results were similar to that of the absorption of the silver phosphate nanoparticles between 400 and 800 nm [22].Therefore, these experimental results indicated that the range of irradiation intensity and wavelength played important roles in the catalytic reaction along with the role of visible light irradiation.Using the same calculation method, the contribution of light to the conversion could be calculated in any wavelength range.As shown in Figure 6, when the wavelength range was between 400 and 650 nm, the contribution of light was 85%.The light contributions to the conversion of benzaldehyde between the wavelength ranges of 400-450, 450-510, 510-650, and 650-800 nm were 10%, 44%, 31%, and 15%, respectively.These results were similar to that of the absorption of the silver phosphate nanoparticles between 400 and 800 nm [22].Therefore, these experimental results indicated that the range of irradiation intensity and wavelength played important roles in the catalytic reaction along with the role of visible light irradiation.

The Recyclability of the Prepared Catalysts
The conversion using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalyst was the highest for the esterification reaction of aldehydes and alcohols of all the prepared catalysts.To further verify that the catalyst had a stronger application value, a life test of the catalyst was performed and the test results are shown in Figure S2.The conversion of benzaldehyde and the selectivity of products  Using the same calculation method, the contribution of light to the conversion could be calculated in any wavelength range.As shown in Figure 6, when the wavelength range was between 400 and 650 nm, the contribution of light was 85%.The light contributions to the conversion of benzaldehyde between the wavelength ranges of 400-450, 450-510, 510-650, and 650-800 nm were 10%, 44%, 31%, and 15%, respectively.These results were similar to that of the absorption of the silver phosphate nanoparticles between 400 and 800 nm [22].Therefore, these experimental results indicated that the range of irradiation intensity and wavelength played important roles in the catalytic reaction along with the role of visible light irradiation.

The Recyclability of the Prepared Catalysts
The conversion using the 71 wt% Ag3PO4/Ag/Bi2O2CO3 catalyst was the highest for the esterification reaction of aldehydes and alcohols of all the prepared catalysts.To further verify that the catalyst had a stronger application value, a life test of the catalyst was performed and the test results are shown in Figure S2.The conversion of benzaldehyde and the selectivity of products

The Recyclability of the Prepared Catalysts
The conversion using the 71 wt % Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 catalyst was the highest for the esterification reaction of aldehydes and alcohols of all the prepared catalysts.To further verify that the catalyst had a stronger application value, a life test of the catalyst was performed and the test results are shown in Figure S2.The conversion of benzaldehyde and the selectivity of products changed little after it was used four times.Compared to the first four times, the conversion of benzaldehyde dwindled when the catalyst was used for the fifth and sixth times.This could have been due to the loss of some Ag 3 PO 4 and Ag nanoparticles during the recycling process, which was in agreement with the TEM (Figure 3i,j) and EDX observations (Figure 3k and Figure S3, and the weight% of Ag changed from 66.64%-18.88% after recycling).

Reaction Mechanism
Based on the experimental results, a possible mechanism for the photocatalytic esterification of benzaldehyde using Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 is presented in Schemes 1 and 2 [22,27].Ag nanoparticles were located between Ag 3 PO 4 and Bi 2 O 2 CO 3 .Ag can act as a trap for electrons as usually happens in semiconductor/metal nanoparticle systems.Under visible light irradiation, electrons and holes were produced from Bi 2 O 2 CO 3 and Ag 3 PO 4 , followed by the transfer of the photo-generated electrons to Ag, while the holes were concentrated on the Ag 3 PO 4 due to the close contact between Ag 3 PO 4 and Bi 2 O 2 CO 3 (Scheme 1, reactions 1 and 2 and Scheme 2).Therefore, Ag played a major role in the transfer of electrons in the reaction of aldehydes and alcohol.Photo-generated electrons and holes were effectively separated, which granted Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 a strong photo-catalytic activity.Therefore, the Ag located between the Bi 2 O 2 CO 3 and Ag 3 PO 4 acted as a charge-carrier transfer material during the esterification process of the aldehydes and alcohols, which effectively prolonged the lifetime of the photo-induced holes produced by Bi 2 O 2 CO 3 and Ag 3 PO 4 .The first step of the reaction involved the loss of a proton from the alcohol to form an alkoxyl radical (Scheme 1, reaction 3 and Scheme 2).Subsequently, the benzaldehyde received an electron and then was reduced to a reactive intermediate, which was then protonized rapidly to generate an α-hydroxyl radical (Scheme 1, reactions 4 and 5 and Scheme 2).Next, the α-hydroxyl radical and alkoxyl radical were combined to generate a relatively stable hemiacetal intermediate (Scheme 1, reaction 6 and Scheme 2).The α-H of the hemiacetal intermediate structure was also attracted by the silver nanoparticles, and hence formed an ester.Finally, H + of Ag-H was transferred to the alkoxyl radical to form an alcohol, leaving the silver nanoparticles (Scheme 1, reactions 7-9 and Scheme 2).The silver and silver phosphate nanoparticle surfaces could then be re-activated by visible light, and a new reaction process could begin [57-62] (Scheme 2).
The reactions are shown as follows (Scheme 1): Catalysts 2017, 7, 276 13 of 19 changed little after it was used four times.Compared to the first four times, the conversion of benzaldehyde dwindled when the catalyst was used for the fifth and sixth times.This could have been due to the loss of some Ag3PO4 and Ag nanoparticles during the recycling process, which was in agreement with the TEM (Figure 3i,j) and EDX observations (Figures 3k and S3, and the weight% of Ag changed from 66.64%-18.88% after recycling).

Reaction Mechanism
Based on the experimental results, a possible mechanism for the photocatalytic esterification of benzaldehyde using Ag3PO4/Ag/Bi2O2CO3 is presented in Scheme 1 and Scheme 2 [22,27].Ag nanoparticles were located between Ag3PO4 and Bi2O2CO3.Ag can act as a trap for electrons as usually happens in semiconductor/metal nanoparticle systems.Under visible light irradiation, electrons and holes were produced from Bi2O2CO3 and Ag3PO4, followed by the transfer of the photo-generated electrons to Ag, while the holes were concentrated on the Ag3PO4 due to the close contact between Ag3PO4 and Bi2O2CO3 (Scheme 1, reactions 1 and 2 and Scheme 2).Therefore, Ag played a major role in the transfer of electrons in the reaction of aldehydes and alcohol.Photo-generated electrons and holes were effectively separated, which granted Ag3PO4/Ag/Bi2O2CO3 a strong photo-catalytic activity.Therefore, the Ag located between the Bi2O2CO3 and Ag3PO4 acted as a charge-carrier transfer material during the esterification process of the aldehydes and alcohols, which effectively prolonged the lifetime of the photo-induced holes produced by Bi2O2CO3 and Ag3PO4.The first step of the reaction involved the loss of a proton from the alcohol to form an alkoxyl radical (Scheme 1, reaction 3 and Scheme 2).Subsequently, the benzaldehyde received an electron and then was reduced to a reactive intermediate, which was then protonized rapidly to generate an α-hydroxyl radical (Scheme 1, reactions 4 and 5 and Scheme 2).Next, the α-hydroxyl radical and alkoxyl radical were combined to generate a relatively stable hemiacetal intermediate (Scheme 1, reaction 6 and Scheme 2).The α-H of the hemiacetal intermediate structure was also attracted by the silver nanoparticles, and hence formed an ester.Finally, H + of Ag-H was transferred to the alkoxyl radical to form an alcohol, leaving the silver nanoparticles (Scheme 1, reactions 7-9 and Scheme 2).The silver and silver phosphate nanoparticle surfaces could then be re-activated by visible light, and a new reaction process could begin [57-62] (Scheme 2).
The reactions are shown as follows (Scheme 1): Scheme 1.The reactions of a proposed mechanism for the esterification of aldehydes and alcohols using Ag3PO4/Ag/Bi2O2CO3.A similar method was applied to prepare catalysts with the 64 wt % Ag 3 PO 4 /Bi 2 O 2 CO 3 .Typically, 1.14 g of Bi 2 O 2 CO 3 and 1.0 g of polyvinyl pyrrolidone (PVP) were dissolved in 30 mL of deionized water and stirred for 30 min.Then, 20 mL of a Na 3 PO 4 solution of a certain concentration was added dropwise to the mixture and stirred for 30 min.Next, 20 mL of an AgNO 3 solution of a certain concentration was added dropwise to the suspension and stirred for a further 5 h to achieve a 3:1 molar ratio of Ag + and PO 4 3+ .Finally, the mixture was centrifuged and washed with deionized water and ethanol several times before being dried at 60 • C. The 10 wt % Ag/Bi 2 O 2 CO 3 was prepared as follows: first, 1.14 g of Bi 2 O 2 CO 3 was dissolved in 30 mL of deionized water and stirred for 30 min.Then, 10 mL of an AgNO 3 solution of a certain concentration was added dropwise to the mixture and stirred for 4 h.Ag nanoparticles were generated by a 300 W UV lamp for 1 h with constant stirring.Finally, the mixture was centrifuged and washed with deionized water and ethanol several times before being dried at 60 • C [47].

Characterization
The crystal phases of the samples were analyzed by X-ray diffraction (XRD) (Rigaku Industrial Corporation, Osaka, Japan) with a RIGAKU D/MAX-2500 X-ray diffractometer using Cu Kα radiation (λ = 1.5405Å) at 40 kV and 100 mA.X-ray photoelectron spectroscopy (XPS) with Al Kα X-ray (hν = 1486.6eV) radiation operating at 150 W (Escalab 250xi, Thermo Fisher Scientific Company, Waltham, MA, USA) was applied to investigate the surface properties.Scanning electron microscopy (SEM model S-4800, Hitachi Limited Company, Tokyo, Japan) was used to characterize the morphology of the obtained composites.The morphology and structure of the samples were examined by transmission electron microscopy (TEM) (FEI Company, Hillsborough, OR, USA) using an FEI Tecnai G2 F20 S-Twin electron microscope, which was operated at an acceleration voltage of 200 kV.A multipoint BET method was applied to determine the Brunauer-Emmett-Teller (BET) (Quantachrome Instruments, Corporate Headquarters, Boynton Beach, FL, USA) specific surface areas.The UV-vis diffuse reflectance spectra (UV-vis DRS) (Hitachi Limited Company, Tokyo, Japan) of the solid samples were obtained using a scanning UV-vis spectrophotometer (U-3900, Hitachi) equipped with an integrated sphere assembly with 100% BaSO 4 as the reflectance sample.The reaction products were quantitatively analyzed with a GC-2014C gas chromatograph (GC-2014C) (Shimadzu Company, Kyoto, Japan).The identity of the product was confirmed with a Trace DSQ II gas chromatograph-mass spectrometer (GC-MS) (Finnigan Company, Silicon valley, CA, USA) at Inner Mongolia University.

The Esterification Reaction of Aldehydes (or Alcohols) and Alcohols
The catalytic esterification of benzaldehyde (or benzyl alcohol) with other alcohols was detected.In a typical reaction, benzaldehyde (or benzyl alcohol, 1.0 mmol), 8 mL of methanol, and the photo-catalyst (30 mg) were mixed together.No base was added into the aldehyde/alcohol mixtures, but a base was added into the alcohol/alcohol mixtures.The flask was then irradiated with a 500 W Philips halogen lamp (wavelength between 400 and 800 nm) under magnetic stirring and in an Ar (for the esterification of aldehydes and alcohols) or air atmosphere (for the esterification of alcohols and alcohols).The conversion and selectivity of the esterification reactions were calculated from the results detected by GC.The products were qualified using GC-MS [63].

The Amination Reaction of Alcohols and Amines
To detect the amination of benzyl alcohol and aniline, benzyl alcohol (1.0 mmol), aniline (0.5 mmol), 6 mL of solvents, base, and the photo-catalyst (30 mg) were mixed together in an air atmosphere.The other conditions were kept the same as in Section 3.3.1.

Reuse of the Catalyst
Based on the excellent activities of the 71 wt % Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 composite, the following experiment was conducted to demonstrate its ability to be recycled.First, 24 group experiments were performed under identical reaction conditions (benzaldehyde (1.0 mmol), methanol (8 mL), 71 wt % Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 catalyst (30 mg), Ar atmosphere, exposure time of 24 h, and light intensity of 4.3 × 10 −2 W•cm −2 ).The catalyst and reactant were centrifuged.The catalyst was then washed with H 3 PO 4 (0.1 mol•L −1 ) and ethanol.Second, using the reused catalysts under the same reaction conditions as above-mentioned, 18 group experiments were conducted simultaneously.Third, the thrice-used catalyst was employed for a further 12 group experiments under the same reaction conditions.Fourth, eight group experiments were conducted using the fourth-used catalyst under the same reaction conditions, followed by an additional six group experiments conducted using the catalyst already used four times under the same reaction conditions.Finally, three group experiments were analyzed with the catalyst already used five times under the same conditions.The results are shown in Figure S2.

Conclusions
Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 composites were fabricated by a joint hydrothermal and precipitation method.The heterogeneous catalyst (71 wt % Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 ) displayed good reactivity in the esterification of aldehydes (or alcohols) and alcohols, and in the synthesis of imines through alcohols and amines under visible light irradiation.The catalyst was stable and could be used at least six times.Visible light was applied for the reaction process at low temperature.These conditions were more advantageous than other systems reported to date.A possible reaction pathway from aldehydes and alcohols to esters was described.S1: BET surface areas of the photo-catalysts supported on Bi 2 O 2 CO 3 and Bi 2 O 2 CO 3 , Table S2: Synthesis of esters from benzyl alcohol and methanol using 71 wt % Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 , Table S3: Synthesis of imines from benzyl alcohol and aniline using 71wt % Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 .

Figure 1 .
Figure 1.X-ray diffraction (XRD) patterns of the different photo-catalysts.(a) XRD of the different catalysts (b) XRD of the different amounts of Ag3PO4/Ag/Bi2O2CO3 catalysts.

Figure 1 .
Figure 1.X-ray diffraction (XRD) patterns of the different photo-catalysts.(a) XRD of the different catalysts (b) XRD of the different amounts of Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 catalysts.
Reaction conditions: aldehyde (1.0 mmol) and Ag3PO4/Ag/Bi2O2CO3 catalyst (30 mg) were added to alcohol (8 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the conditions: aldehyde (1.0 mmol) and Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 catalyst (30 mg) were added to alcohol (8 mL).The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the visible light source under an Ar atmosphere at 35 ± 3 • C.After running for 24 h, the reaction conversion and selectivity were determined by GC.

Figure 6 .
Figure 6.Effect of the light wavelength on the esterification of benzaldehyde using 71 wt% Ag3PO4/Ag/Bi2O2CO3.

Figure 6 .
Figure 6.Effect of the light wavelength on the esterification of benzaldehyde using 71 wt% Ag3PO4/Ag/Bi2O2CO3.

Figure 6 .
Figure 6.Effect of the light wavelength on the esterification of benzaldehyde using 71 wt % Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 .

Scheme 1 .
Scheme 1.The reactions of a proposed mechanism for the esterification of aldehydes and alcohols using Ag 3 PO 4 /Ag/Bi 2 O 2 CO 3 .

Table 1 .
Synthesis of esters from different aldehydes and alcohols using 71 wt% Ag3PO4/Ag/Bi2O2CO3.The reaction flask was stirred magnetically and was irradiated with a 500 W Philips halogen lamp (wavelength range of 400-800 nm, and a light intensity of 2.5 × 10 −2 W•cm −2 ) as the

Table 2 .
Synthesis of esters from benzaldehyde and methanol using different photo-catalysts.

Table 2 .
Synthesis of esters from benzaldehyde and methanol using different photo-catalysts.
−2 W•cm −2 ) as the visible light source