Novel Enzyme-Free Multifunctional Bentonite/Polypyrrole/Silver Nanocomposite Sensor for Hydrogen Peroxide Detection over a Wide pH Range

Precise designs of low-cost and efficient catalysts for the detection of hydrogen peroxide (H2O2) over wide ranges of pH are important in various environmental applications. Herein, a versatile and ecofriendly approach is presented for the rational design of ternary bentonite-silylpropyl-polypyrrole/silver nanoarchitectures (denoted as BP-PS-PPy/Ag) via the in-situ photo polymerization of pyrrole with salinized bentonite (BP-PS) in the presence of silver nitrate. The Pyrrolyl-functionalized silane (PS) is used as a coupling agent for tailoring the formation of highly exfoliated BP-PS-PPy sheet-like nanostructures ornamented with monodispersed Ag nanoparticles (NPs). Taking advantage of the combination between the unique physicochemical properties of BP-PS-PPy and the outstanding catalytic merits of Ag nanoparticles (NPs), the as-synthesized BP-PS-PPy/Ag shows a superior electrocatalytic reduction and high-detection activity towards H2O2 under different pH conditions (from 3 to 10). Intriguingly, the UV-light irradiation significantly enhances the electroreduction activity of H2O2 substantially, compared with the dark conditions, due to the high photoelectric response properties of Ag NPs. Moreover, BP-PS-PPy/Ag achived a quick current response with a detection limit at 1 μM within only 1 s. Our present approach is green, facile, scalable and renewable.


Introduction
Hydrogen peroxide (H 2 O 2 ) is important in myriad industrial, environmental remediation, biological, and pharmaceutical applications [1][2][3][4][5][6][7][8]. Moreover, H 2 O 2 is ubiquitously generated as a by-product during cholesterol [9], glucose [10], glutamate [11], and lactate [12] oxidation processes. Numerous efforts are spent to develop efficient analytical methods for the detection of H 2 O 2 , namely, high-pressure liquid chromatography, colorimetric, positron emission tomography, electrochemical, bioluminescence and chemiluminescence [13][14][15][16][17]. Unlike these approaches, the electrochemical methods [18] have various advantages, including the low cost, safety, simplicity, accuracy, fast response, and high sensitivity, which are essential for the practical applications [19]. Noble metals-based catalysts are well-imminent with their outstanding electrocatalytic activity and sensitivity towards enzymtic-free H 2 O 2 detection [20]. Among these noble metals, silver nanoparticles (Ag NPs) have unique optical, catalytic, and anti-bacterial properties [21][22][23][24]. Furthermore, the great abundance in the nature of Ag makes it more feasible for large-scale applications. Moreover, Ag NPs can provide oxygenated species facilitates the O-H splitting at low potential along with high tolerance for the reaction intermediates. dried at 40 • C for 48 h. Following that, a 1 g of as-obtained BP-PS was dispersed in 50 mL ethanol and then 10 mL of H 2 O containing 1.68 g of AgNO 3 was quickly added under stirring at room temperature followed by a dropwise of Pyrrole (20 mL, 0.5 mol/L) under the UV-illumination at 365 nm for 2 h. Finally, BP-PS-PPy/Ag nanoarchitectures were obtained via centrifugation at 7000 rpm for 10 min and washing cycles with ethanol for 4 times and then dried at 40 • C for 24 h and kept for further characterizations.

Electrocatalytic Reduction of Hydrogen Peroxide (H 2 O 2 )
The cyclic voltammograms (CVs) and chronoamperometric measurements were measured on a Gamry electrochemical analyzer (reference 3000, Gamry Co., Warminster, PA, USA), using a three-electrode cell, including a platinum wire, Ag/AgCl, glassy carbon (GC, 5 mm) as a counter, reference and working electrodes, respectively. The GC electrodes were covered with 10 µL of each catalyst followed by the addition of 5 µL Nafion (0.05%) and left to be fully dried before the measurements. For the photocatalytic reaction, a three-electrode photo-glass cell was used, and the light source was Biogro ozone-free xenon lamp (100 mW/cm 2 , HK, China). The CVs measurements of each catalyst were tested in aqueous solutions of saline phosphate buffer (pH 7.4) at 50 mV s −1 without and with an aqoues solution of H 2 O 2 (20 µM). The tested solutions were deareated by purging high purity nitrogen gas for 30 min prior to the experiment. Figure 1 illustrates the sequential steps for preparing the BP-PS-PPY/Ag ternary hybrids through two steps: First BP is grafted with amine groups using 3-aminopropyltriethoxysilane, then, pyrrole and AgNO 3 are added to the suspension prior to exposure to the UV light under mixing.

Results and Discussion
The N-rich PPy can easily accelerate the photoreduction of AgNO 3 to form Ag NPs and allow their anchoring on N-atoms of pyrrole during the photopolymerization step. This led to the in-situ formation of monodispersed Ag NPs on the surface of the resulting BP-PS-PPY hybrid nanocomposite. Figure 2 shows the detailed photopolymerization mechanism of pyrrole. First, the excited state of Ag + strips an electron from pyrrole resulting in the formation of pyrrole radical cations and the reduction of Ag + to metal. Two of these radical cations then couple to a dimer (dimerization) with deprotonation, leading to a bipyrrole. After the deprotonation, the bipyrrole is reoxidized and couples with another radical cation. These radical cations can react with pyrrole radical cations to form the PPy chain (chain growth) [40]. The N-rich PPy can easily accelerate the photoreduction of AgNO3 to form Ag NPs and allow their anchoring on N-atoms of pyrrole during the photopolymerization step. This led to the in-situ formation of monodispersed Ag NPs on the surface of the resulting BP-PS-PPY hybrid nanocomposite. Figure 2 shows the detailed photopolymerization mechanism of pyrrole. First, the excited state of Ag+ strips an electron from pyrrole resulting in the formation of pyrrole radical cations and the reduction of Ag+ to metal. Two of these radical cations then couple to a dimer (dimerization) with deprotonation, leading to a bipyrrole. After the deprotonation, the bipyrrole is reoxidized and couples with another radical cation. These radical cations can react with pyrrole radical cations to form the PPy chain (chain growth) [40].  Figure 3a shows the TEM image of typically formed Ag-free BP-PS, which was formed in multilayers of sheet-like nanostructures (Figure 3a). The high-magnification TEM show that, the as-made nanosheets were not exfoliated and with a slight agglomeration (Figure 3b). Intriguingly enough, the nanosheet morphology of BP-PS was fully preserved after the photopolymerization process in the  The N-rich PPy can easily accelerate the photoreduction of AgNO3 to form Ag NPs and allow their anchoring on N-atoms of pyrrole during the photopolymerization step. This led to the in-situ formation of monodispersed Ag NPs on the surface of the resulting BP-PS-PPY hybrid nanocomposite. Figure 2 shows the detailed photopolymerization mechanism of pyrrole. First, the excited state of Ag+ strips an electron from pyrrole resulting in the formation of pyrrole radical cations and the reduction of Ag+ to metal. Two of these radical cations then couple to a dimer (dimerization) with deprotonation, leading to a bipyrrole. After the deprotonation, the bipyrrole is reoxidized and couples with another radical cation. These radical cations can react with pyrrole radical cations to form the PPy chain (chain growth) [40].  Figure 3a shows the TEM image of typically formed Ag-free BP-PS, which was formed in multilayers of sheet-like nanostructures (Figure 3a). The high-magnification TEM show that, the as-made nanosheets were not exfoliated and with a slight agglomeration (Figure 3b). Intriguingly enough, the nanosheet morphology of BP-PS was fully preserved after the photopolymerization process in the  Figure 3a shows the TEM image of typically formed Ag-free BP-PS, which was formed in multi-layers of sheet-like nanostructures (Figure 3a). The high-magnification TEM show that, the as-made nanosheets were not exfoliated and with a slight agglomeration ( Figure 3b). Intriguingly enough, the nanosheet morphology of BP-PS was fully preserved after the photopolymerization process in the presence of PPy and AgNO 3 ( Figure 3c). Meanwhile, the as-obtained BP-PS-PPy nanosheets were highly exfoliated without any noticed aggregation. This is attributed to anchoring of Ag NPs on N-atoms of PPy, thus precluding the agglomeration of the as-formed nanosheets during the polymerization step. Mono-dispersed Ag NPs with an average diameter of 82 nm were well distributed on the surface of the BP-PS-PPy nanosheets ( Figure 3d). This is mainly attributed to the great reduction power of PPy monomer towards AgNO 3 under UV-light irradiation. The crystalline structure of the as-made BP and BP-PS-PPy/Ag nanoarchitectures is investigated by the XRD analysis ( Figure 4a). The average crystallite size of AgNPs estimated through XRD (using Scherrer's equation) [41] is 80.9 ± 0.7 nm, which matches the size estimated by TEM. distributed on the surface of the BP-PS-PPy nanosheets (Figure 3d). This is mainly attributed to the great reduction power of PPy monomer towards AgNO3 under UV-light irradiation. The crystalline structure of the as-made BP and BP-PS-PPy/Ag nanoarchitectures is investigated by the XRD analysis ( Figure 4a). The average crystallite size of AgNPs estimated through XRD (using Scherrer's equation) [41] is 80.9 ± 0.7 nm, which matches the size estimated by TEM.  great reduction power of PPy monomer towards AgNO3 under UV-light irradiation. The crystalline structure of the as-made BP and BP-PS-PPy/Ag nanoarchitectures is investigated by the XRD analysis ( Figure 4a). The average crystallite size of AgNPs estimated through XRD (using Scherrer's equation) [41] is 80.9 ± 0.7 nm, which matches the size estimated by TEM.  The results show that BP displays the typical diffraction patterns with an amorphous crystalline structure as reported elsewhere [42,43]. Meanwhile, BP-PS-PPy/Ag reveals the typical, {111}, {200}, {220}, and {311} facets of face-centered cubic (fcc) structure of Ag ( Figure 4a) [44,45]. These patterns account for the metallic nature of Ag particles produced after UV-induced reaction of Py and AgNO 3 as judged from JCPDS file No. 00-001-1164. Interestingly, XRD patterns of Ag are slightly positively shifted relative to pure Ag NPs patterns previously reported in the literature [46], demonstrating its electronic interaction with BP-PS-PPy [47,48]. Intriguingly, BP-PS-PPyAg NPs does not display the {001} facet of BP, indicating the formation of complete exfoliated hybrid BP-PS-PPy/Ag nanocomposite in line with the TEM micrograph. XPS is used to confirm the electronic structure and surface composition  Table 1 reveals the surface composition evaluated by the XPS, which depicts the main elements of BP and BP-PS-PPy/Ag nanoarchitecture. The determined atomic ratios of N/Ag are about 4.69/1.6, respectively, inferring the strong affinity of PPy towards AgNO 3 . Meanwhile, the high resolved amount of C (35%) in BP-Ps-PPy/Ag is mainly originated from the multiple repeated units of PPy (C 4 H 2 N-), indicating the formation of PPy/Ag grafted BP-PS. The high-resolution spectrum of Ag 3d reveals only two main peaks of Ag 3d 5/2 at 368.1 eV and Ag 3d 3/2 at 374.1 eV. The absence of any oxide phases of Ag indicates the purity of the as-formed Ag NPs. The binding energies of Ag 3d are slightly blue-shifted relative to pure Ag. This is plausibly attributed to the interaction between Ag NPs and N-atoms of PPy. The N 1s spectrum is deconvoluted to three peaks assigned to C=N, C-N, and N + at 398.4, 400.3 and 401.7 eV respectively, which are the predominant peaks for PPy. Various approaches were successfully developed for precise design of PPY/Ag-based nanocomposites [50]. However, the facile synthesis of ternary BP-PS-PPy/Ag nanoarchitecture remains a significant challenge and is rarely reported to the best of our knowledge [34,35]. Meanwhile, previous reports emphasized only the multiple step reactions, which isolate between the preparation of Ag NPs and PPy. Different from these methods, our presented approach is easy, and allows the synthesis of ternary BP-PS-PPy/Ag. This is derived by the in-situ photopolymerization of PPy in the presence of BP-PS and AgNO3 as a photosensitizer, currently Py monomer facilitates the reduction of AgNO3 to form Ag NPs (Figure 1). Consequently, the as-formed PY-Ag bonded subsequently with BP-Ps, which were self-assembled to form nanosheets after the complete photopolymerization. It should be noticed that, Ag NPs prevent the agglomeration of the nanosheets Various approaches were successfully developed for precise design of PPY/Ag-based nanocomposites [50]. However, the facile synthesis of ternary BP-PS-PPy/Ag nanoarchitecture remains a significant challenge and is rarely reported to the best of our knowledge [34,35]. Meanwhile, previous reports emphasized only the multiple step reactions, which isolate between the preparation of Ag NPs and PPy. Different from these methods, our presented approach is easy, and allows the synthesis of ternary BP-PS-PPy/Ag. This is derived by the in-situ photopolymerization of PPy in the presence of BP-PS and AgNO 3 as a photosensitizer, currently Py monomer facilitates the reduction of AgNO 3 to form Ag NPs (Figure 1). Consequently, the as-formed PY-Ag bonded subsequently with BP-Ps, which were self-assembled to form nanosheets after the complete photopolymerization. It should be noticed that, Ag NPs prevent the agglomeration of the nanosheets during the polymerization, results in high-exfoliated nanosheets decorated with Ag NPs. This structural and compositional feature is important in electrocatalytic applications. It should be noticed that, the electroreduction activity of H 2 O 2 on BP-Ps-PPy/Ag hybrid composite was not yet reported [35].
The electrocatalytic activity of the typical prepared BP-PS-PPy/Ag nanocomposites is benchmarked relative to BP-PPy/Ag and BP towards the reduction of H 2 O 2 detection. Figure 6a represents the CVs of the as-made catalysts measured in an aqueous solution of PBS (pH 7.4) at a scan rate of 50 mV s −1 with potential range (−0.6 to 0.6 V vs. Ag/AgCl). All electrocatalysts reveal the typical CVs featured including hydrogen adsorption/desorption, Ag-redox, and oxygen evolution. The capacitance currents of BP-PS-PPy/Ag and BP-PPy/Ag were significantly higher than that of metal-free BP, indicating its higher conductivity and surface area. In addition, the capacitive current increases with the surface area.  Figure 6b shows the CVs measured in PBS solution containing 20 μM of H2O2 at 50 mV s −1 which depicts the higher H2O2 reduction activity of BP-PS-PPy/Ag compared with its counterpart BP-PPy/Ag and BP nanostructures. BP-PS-PPy/Ag produces a higher current density under any applied potential than that from the BP-PPy/Ag, as can be seen from the linear sweep voltammograms shown in Figure 6c. This is owing to the combination of BP-PS-PPy and Ag NPs, which enhances the electrical conductivity and provide more active sites for H2O2 reduction. In this regard, the H2O2 reduction current (Jred) on BP-PS-PPy/Ag (−2.78 mA cm −2 ) is around three times higher than that on BP-PPy/Ag (−0.81 mA cm −2 ) (Figure 6d), inferring the potent electrocatalytic behavior of BP-PS-PPy/Ag. This is evidenced in the positive onset reduction potential (Eonset) on BP-PS-PPy/Ag (0.075 V) compared with that on BP-PPy/Ag (0.086 V), owing to its higher conductivity (Figure 6d). This indicates the fast reduction kinetics on BP-PS-PPy/Ag. The CVs were measured on  Figure 6b shows the CVs measured in PBS solution containing 20 µM of H 2 O 2 at 50 mV s −1 which depicts the higher H 2 O 2 reduction activity of BP-PS-PPy/Ag compared with its counterpart BP-PPy/Ag and BP nanostructures. BP-PS-PPy/Ag produces a higher current density under any applied potential than that from the BP-PPy/Ag, as can be seen from the linear sweep voltammograms shown in Figure 6c. This is owing to the combination of BP-PS-PPy and Ag NPs, which enhances the electrical conductivity and provide more active sites for H 2 O 2 reduction. In this regard, the H 2 O 2 reduction current (J red ) on BP-PS-PPy/Ag (−2.78 mA cm −2 ) is around three times higher than that on BP-PPy/Ag (−0.81 mA cm −2 ) (Figure 6d), inferring the potent electrocatalytic behavior of BP-PS-PPy/Ag. This is evidenced in the positive onset reduction potential (E onset ) on BP-PS-PPy/Ag (0.075 V) compared with that on BP-PPy/Ag (0.086 V), owing to its higher conductivity (Figure 6d). This indicates the fast reduction kinetics on BP-PS-PPy/Ag. The CVs were measured on BP-Ps-PPy/Ag in an aqueous solution of PBS (pH 7) containing 20 µM H 2 O 2 at different scan rates (Figure 7b). It is obvious that the reduction current peak increased steadily upon increasing the scan rate from 50 to 250 mV s −1 , inferring the the quick mass trsnafre on BP-PS-PPy/Ag. The corresponding plot of the peak current versus the square root of the scan rate displayed a linear relationship.  Figure 7a shows that the H2O2 reduction currents is proportionally enhanced with increasing the concentration of H2O2 from 1 μM to 20 μM. Moreover, chronoamperometry study (J-T in Figure 7c) which is done by applying 0.2 V on BP-PS-PPy/Ag electrode with adding different concentrations of H2O2 during maintaining PBS in a stirring condition shows a rapid and sensitive response to H2O2 as the response current increases with increasing the H2O2 concentration and the current plataeu is achieved in 2 s. As developing an efficient catalyst for electrocatalytic reduction of H2O2 over wide ranges of pH is a significant challenge, the H2O2 reduction activity on BP-Ps-PPy/Ag nanoarchitectures was investigated under different pH values ranged from 3 to 10 (Figure 7d). BP-Ps-PPy/Ag is found to be able to reduce H2O2 under diffter pH values (3,7, and 10). The reduction current achieved at a pH of 10 (-5.03 mA cm −2 ) is almost 2-and 4-fold higher than that at a pH of 7 and 3, respectively. This is owing to the fast kinetics of H2O2 reduction under alkaline conditions. It should be noticed that under acidic conditions we could not resolve any additional peak for the oxidation of Ag, indicating its stability against corrosion. This can be attributed to the strong electronic interaction between BP-PS-PPy and Ag NPs, which stabilizes Ag against dissolution under acidic conditions. The durability of the electrocatalysts is a decisive factor in large-scale applications. The stability of the typically prepared BP-PS-PPy/Ag nanoarchitectures is investigated via benchmarking the chronoamperometric current-time with a consecutive addition of H2O2 into PBS  Figure 7a shows that the H 2 O 2 reduction currents is proportionally enhanced with increasing the concentration of H 2 O 2 from 1 µM to 20 µM. Moreover, chronoamperometry study (J-T in Figure 7c) which is done by applying 0.2 V on BP-PS-PPy/Ag electrode with adding different concentrations of H 2 O 2 during maintaining PBS in a stirring condition shows a rapid and sensitive response to H 2 O 2 as the response current increases with increasing the H 2 O 2 concentration and the current plataeu is achieved in 2 s. As developing an efficient catalyst for electrocatalytic reduction of H 2 O 2 over wide ranges of pH is a significant challenge, the H 2 O 2 reduction activity on BP-Ps-PPy/Ag nanoarchitectures was investigated under different pH values ranged from 3 to 10 (Figure 7d). BP-Ps-PPy/Ag is found to be able to reduce H 2 O 2 under diffter pH values (3, 7, and 10). The reduction current achieved at a pH of 10 (-5.03 mA cm −2 ) is almost 2-and 4-fold higher than that at a pH of 7 and 3, respectively. This is owing to the fast kinetics of H 2 O 2 reduction under alkaline conditions. It should be noticed that under acidic conditions we could not resolve any additional peak for the oxidation of Ag, indicating its stability against corrosion. This can be attributed to the strong electronic interaction between BP-PS-PPy and Ag NPs, which stabilizes Ag against dissolution under acidic conditions. The durability of the electrocatalysts is a decisive factor in large-scale applications. The stability of the typically prepared BP-PS-PPy/Ag nanoarchitectures is investigated via benchmarking the chronoamperometric current-time with a consecutive addition of H 2 O 2 into PBS (pH 7.4) at an applied potential of (−0.3 V). The results reveal the rapid chronoamperometric responses of BP-PS-PPy/Ag to changing the concentrations of H 2 O 2 along with typical steady-state current rising until reach the stable value. Interestingly, BP-Ps-PPy/Ag achieved a quick current response at 1 µM within 1 s, which is superior to previously reported for Fe 3 O 4 /PPy/Ag nanocomposite (5 s), PPy nanofiber-AgNPs-rGO (3 s), and PPyNPT-Ag (3 s) [51][52][53]. The calibration curves depict that the linear detection ranges of H 2 O 2 ranged from 1 µM to 20 µM with a detection limit of 1 µM. The as-synthesized BP-PS-PPy/Ag showed a detection limit of H 2 O 2 detection lower than that of beforehand reported 1 µM and 1.7 µM and 1.8 µM [51][52][53].
The H 2 O 2 reduction performance on BP-Ps-PPy/Ag, is measured under the UV-visible light irradiation to further sort out the catalytic effect of Ag NPs (Figure 8a). Interestingly, the H 2 O 2 reduction current on BP-Ps-PPy/Ag under light (5.3 mA cm −2 ) is almost double its counterpart measured in the dark (2.8 mA cm −2 ). Meanwhile, the E onset under light is significantly more positive than that under dark at any applied potential point as indicated by the dashed line in Figure 8b. This implies the more facile reduction kinetics under light, ascribed to the inbuilt optical properties of Ag NPs, which produce photo-generated electrons and release them to the BP-Ps-PPy. curves depict that the linear detection ranges of H2O2 ranged from 1 μM to 20 μM with a detection limit of 1 μM. The as-synthesized BP-PS-PPy/Ag showed a detection limit of H2O2 detection lower than that of beforehand reported 1 μM and 1.7 μM and 1.8 μM [51][52][53]. The H2O2 reduction performance on BP-Ps-PPy/Ag, is measured under the UV-visible light irradiation to further sort out the catalytic effect of Ag NPs (Figure 8a). Interestingly, the H2O2 reduction current on BP-Ps-PPy/Ag under light (5.3 mA cm −2 ) is almost double its counterpart measured in the dark (2.8 mA cm −2 ). Meanwhile, the Eonset under light is significantly more positive than that under dark at any applied potential point as indicated by the dashed line in Figure 8b. This implies the more facile reduction kinetics under light, ascribed to the inbuilt optical properties of Ag NPs, which produce photo-generated electrons and release them to the BP-Ps-PPy. These findings clearly display the superior electrocatalytic H2O2 reduction activity of BP-PS-PPy/Ag nanoarchitecture than that of BP-PPy/Ag and BP. This is attributed to the combination between the remarkable physicochemical properties of BP-PS-PPy and outstanding catalytic and optical properties of Ag NPs [54,55]. Mainly, the exfoliated BP-PS-PPy nanosheets provide various adsorptions and active sites for H2O2, which maximize the utilization of Ag NPs during H2O2 reduction [56,57]. Meanwhile, the synergistic and electronic interaction between Ag NPs and BP-PS-PPy originates various accessible active sites for H2O2 reduction as well as produces oxygenated species which accelerates the reduction kinetics at low overpotentials. Table 2 compares the performances of the actual electrocatalyst to those of similar ones prepared in different conditions. The as-prepared BP-PS-PPY/Ag present the lowest detection limit.  These findings clearly display the superior electrocatalytic H 2 O 2 reduction activity of BP-PS-PPy/Ag nanoarchitecture than that of BP-PPy/Ag and BP. This is attributed to the combination between the remarkable physicochemical properties of BP-PS-PPy and outstanding catalytic and optical properties of Ag NPs [54,55]. Mainly, the exfoliated BP-PS-PPy nanosheets provide various adsorptions and active sites for H 2 O 2 , which maximize the utilization of Ag NPs during H 2 O 2 reduction [56,57]. Meanwhile, the synergistic and electronic interaction between Ag NPs and BP-PS-PPy originates various accessible active sites for H 2 O 2 reduction as well as produces oxygenated species which accelerates the reduction kinetics at low overpotentials. Table 2 compares the performances of the actual electrocatalyst to those of similar ones prepared in different conditions. The as-prepared BP-PS-PPY/Ag present the lowest detection limit.

Conclusions
To sum up, a facile, versatile, low-cost and scalable roadmap is presented for controlled synthesis of BP-PS-PPy/Ag nanoarchitectures. This is simply based on the in-situ photopolymerization of pyrrole in the presence of BP-PS and AgNO 3 as a photosensitizer. Meanwhile, pyrrole facilitated the in-situ reduction of silver nitrate to form Ag NPs. The as-produced nanoarchitecture is assembled in well-defined exfoliated BP-PS-PPy nanosheets decorated with monodispersed Ag NPs. The detection limit of H 2 O 2 in the presence of BP-Ps-PPy/Ag was about 1 µM as well as a fast response of 1 s. Currently, BP-PS-PPy/Ag is found to be an efficient catalyst for H 2 O 2 reduction over wide ranges of pH, ranging from 3 to 10. Moreover, the UV-light irradiation enhanced the photocatalytic H 2 O 2 reduction activity of BP-PS-PPy/Ag, owing to the optical properties of Ag NPs. The presented method may open new windows towards usage of prepared BP-PS-PPy/Ag for various catalytic reactions.