Carbonized Aminal-Linked Porous Organic Polymers Containing Pyrene and Triazine Units for Gas Uptake and Energy Storage

Porous organic polymers (POPs) have plenteous exciting features due to their attractive combination of microporosity with π-conjugation. Nevertheless, electrodes based on their pristine forms suffer from severe poverty of electrical conductivity, precluding their employment within electrochemical appliances. The electrical conductivity of POPs may be significantly improved and their porosity properties could be further customized by direct carbonization. In this study, we successfully prepared a microporous carbon material (Py-PDT POP-600) by the carbonization of Py-PDT POP, which was designed using a condensation reaction between 6,6′-(1,4-phenylene)bis(1,3,5-triazine-2,4-diamine) (PDA-4NH2) and 4,4′,4′′,4′′′-(pyrene-1,3,6,8-tetrayl)tetrabenzaldehyde (Py-Ph-4CHO) in the presence of dimethyl sulfoxide (DMSO) as a solvent. The obtained Py-PDT POP-600 with a high nitrogen content had a high surface area (up to 314 m2 g−1), high pore volume, and good thermal stability based on N2 adsorption/desorption data and a thermogravimetric analysis (TGA). Owing to the good surface area, the as-prepared Py-PDT POP-600 showed excellent performance in CO2 uptake (2.7 mmol g−1 at 298 K) and a high specific capacitance of 550 F g−1 at 0.5 A g−1 compared with the pristine Py-PDT POP (0.24 mmol g−1 and 28 F g−1).


Synthesis of Py-PDT POP
PDT-4NH2 (0.26 g, 0.87 mmol), Py-Ph-4CHO (0.17 g, 0.27 mmol), and DMSO (20 mL were added into a Schlenk flask. The flask was exposed to a thaw cycle three times. Th flask was then heated to 180 °C and stirred for three days under nitrogen. After coolin the flask to room temperature, the product was separated by filtration and washed wit DMF, MeOH, and acetone. The brown powder of Py-PDT POP was dried under a vacuum at 100 °C for 24 h. Finally, Py-PDT POP was obtained as a dark brown powder (70% Scheme 2a).  A mixture of KOH (1.124 g, 20 mmol) and 2-cyanoguanidine (4.048 g, 48 mmol) in DMF (160 mL) was added to a flask containing BZ-2CN (1.544 g, 9.2 mmol) in DMF (40 mL). The flask was magnetically stirred under nitrogen at 130 • C for 20 h (refluxing system). The obtained suspension was washed with MeOH and EtOH many times and dried to afford PDT-4NH 2 as a white powder (Scheme 1b; 75%). The FTIR (KBr, cm −1 ; Figure 1a

Synthesis of Py-PDT POP
PDT-4NH 2 (0.26 g, 0.87 mmol), Py-Ph-4CHO (0.17 g, 0.27 mmol), and DMSO (20 mL) were added into a Schlenk flask. The flask was exposed to a thaw cycle three times. The flask was then heated to 180 • C and stirred for three days under nitrogen. After cooling the flask to room temperature, the product was separated by filtration and washed with DMF, MeOH, and acetone. The brown powder of Py-PDT POP was dried under a vacuum at 100 • C for 24 h. Finally, Py-PDT POP was obtained as a dark brown powder (70%; Scheme 2a).

Synthesis of Py-PDT POP-600
The as-prepared Py-PDT POP was placed in a ceramic boat into a tubular furnace and carbonized at 600 • C for 8 h (heating rate of 5 • C min −1 ) under a N 2 atmosphere. After allowing the tube furnace's temperature to reach the ambient temperature, the carbonized product was collected as a black powder and named Py-PDT POP-600 (Scheme 2b).

Synthesis of Py-PDT POP-600
The as-prepared Py-PDT POP was placed in a ceramic boat into a tubular and carbonized at 600 °C for 8 h (heating rate of 5 °C min −1 ) under a N2 atmosphe allowing the tube furnace's temperature to reach the ambient temperature, the car product was collected as a black powder and named Py-PDT POP-600 (Scheme 2

Synthesis and Characterization of Py-Ph-4CHO, PDT-4NH2, and Py-PDT
Scheme 1 shows the synthesis of the Py-Ph-4CHO and PDT-4NH2 monome rene molecule was reacted with a neat bromine solution in the presence of C6H5N elevated temperature (120 °C) to afford Py-Br4 as a light green solid with a hi (Scheme S1). The obtained Py-Br4 was insoluble in all organic solvents and use next step without purification. The bands in the FTIR pattern of Py-Br4 centered and 682 cm −1 for aromatic C-H and C-Br units ( Figure S1). The Py-Ph-4CHO m was synthesized through the Suzuki coupling reaction of Py-Br4 with FP-BO in t ence of K2CO3/DO/H2O at 110 °C for three days to afford a yellow solid (Scheme 1 H NMR results of the Py-Br4 and Py-Ph-4CHO monomers are not provided be their poor solubility. A reaction of 2-cyanoguanidine with 1,4-dicyanobenzene (B was then created in the presence of KOH and DMF to obtain PDT-4NH2 as a white (Scheme 1b). The proton's signals appeared at 6.8 and 8.3 ppm due to the presen amino group and a phenyl ring in the PDT-4NH2 ( Figure S2). Scheme 2a illust synthetic route for preparing the porous organic polymer named Py-PDT POP fro 4NH2 and Py-Ph-4CHO as building monomers. The Py-PDT POP was con through a Schiff base polycondensation reaction between 6,6′-(1,4-phenylene)bis( azine-2,4-diamine) (PDA-4NH2) and 4,4′,4′′,4′′′-(pyrene-1,3,6,8-tetrayl)tetrabenza (Py-Ph-4CHO) in the presence of DMSO at 180 °C for 72 h under N2 without u

Results and Discussion
3.1. Synthesis and Characterization of Py-Ph-4CHO, PDT-4NH 2 , and Py-PDT Scheme 1 shows the synthesis of the Py-Ph-4CHO and PDT-4NH 2 monomers. A pyrene molecule was reacted with a neat bromine solution in the presence of C 6 H 5 NO 2 at an elevated temperature (120 • C) to afford Py-Br 4 as a light green solid with a high yield (Scheme S1). The obtained Py-Br 4 was insoluble in all organic solvents and used in the next step without purification. The bands in the FTIR pattern of Py-Br 4 centered at 3053 and 682 cm −1 for aromatic C-H and C-Br units ( Figure S1). The Py-Ph-4CHO monomer was synthesized through the Suzuki coupling reaction of Py-Br 4 with FP-BO in the presence of K 2 CO 3 /DO/H 2 O at 110 • C for three days to afford a yellow solid (Scheme 1a). The 1 H NMR results of the Py-Br 4 and Py-Ph-4CHO monomers are not provided because of their poor solubility. A reaction of 2-cyanoguanidine with 1,4-dicyanobenzene (BZ-2CN) was then created in the presence of KOH and DMF to obtain PDT-4NH 2 as a white powder (Scheme 1b). The proton's signals appeared at 6.8 and 8.3 ppm due to the presence of an amino group and a phenyl ring in the PDT-4NH 2 ( Figure S2). Scheme 2a illustrates the synthetic route for preparing the porous organic polymer named Py-PDT POP from PDT-4NH 2 and Py-Ph-4CHO as building monomers. The Py-PDT POP was constructed through a Schiff base polycondensation reaction between 6,6 -(1,4-phenylene)bis(1,3,5-triazine-2,4diamine) (PDA-4NH 2 ) and 4,4 ,4 ,4 -(pyrene-1,3,6,8-tetrayl)tetrabenzaldehyde (Py-Ph-4CHO) in the presence of DMSO at 180 • C for 72 h under N 2 without using any catalyst (Scheme 2a). The as-synthesized Py-PDT POP was washed with DMF, DMSO, THF, MeOH, and acetone to remove the unreacted Py-Ph-4CHO and PDT-4NH 2 . The Py-PDT POP was then placed into a tube furnace for calcination at 600 • C under N 2 for 8 h to afford Py-PDT POP-600 as a black precipitate (Scheme 2b). Several instrumental techniques (FTIR, ssNMR, TGA, TEM, SEM, BET, and XPS) were used to characterize our porous Py-PDT POP and Py-PDT POP-600 materials. The chemical molecular structure of building monomers (Py-Ph-4CHO and PDT-4NH 2 ) and the obtained Py-PDT POP were confirmed using solid-state 13 C NMR and FTIR, as presented in Figure 1. Figure 1a displays the FTIR profile (recorded at 25 • C) of Py-Ph-4CHO, PDT-4NH 2 , and Py-PDT POP. The FTIR spectrum of Py-Ph-4CHO displayed an absorption band at 3061 cm −1 for the C-H aromatic, 2810 and 2717 cm −1 for the aldehydic C-H, 1700 cm −1 for C=O, and 1598 cm −1 for the C=C bond. The FTIR spectrum of PDT-4NH 2 showed absorption bands at 3300, 3123, and 1624 for the NH 2 group, aromatic C-H, and C=C bonds. The peaks at ca. 1547 and 1364 cm −1 in the FTIR spectra (Figure 1a) of PDT-4NH 2 and Py-PDT POP indicated the triazine moiety's existence in the chemical structure [60,61]. Comparing the FTIR spectrum of the Py-Ph-4CHO monomer and the as-prepared Py-PDT POP revealed that the characteristic absorption peak intensity of the aldehydic units became weak in the FTIR profile of Py-PDT POP, indicating a complete condensation reaction between Py-Ph-4CHO and PDT-4NH 2 to afford Py-PDT POP with a high cross-linking density and aminal linkage. The chemical structures of PDT-4NH 2 , Py-Ph-4CHO, and Py-PDT POP were further examined by solid-state 13 (Figure 1c). The TGA results revealed that the 10% weight loss values of PDT-4NH 2 , Py-Ph-4CHO, and Py-PDT POP were 355, 338, and 320 • C, respectively. The char yield estimations at 800 • C for PDT-4NH 2 , Py-Ph-4CHO, and Py-PDT POP were 35, 34, and 39 wt%, respectively. Furthermore, the presence of nitrogen, oxygen, and carbon atoms on the surface of Py-PDT POP was confirmed using an XPS analysis, as displayed in Figure 1d. The XPS profile of Py-PDT POP showed signals at 284.5 eV, 400.17 eV, and 531.39 eV, which were attributed to the C atoms of the aromatic rings, N atoms in the triazine units, and O atoms for the terminal CHO group, respectively. According to the FTIR and TGA results, the information mentioned above supported the formation of the aminal linkage to construct the Py-PDT POP framework with good thermal stability. El-Kadri et al. prepared fluorescent NRAPOP-1 and NRAPOP-2 through aminal linkage for I 2 capture and Fe 3+ detection [62]. The same group constructed TALPOP based on anthracene and triazine units for I 2 uptake [63].
The BET surface area, pore size diameter, and total pore volume of Py-PDT POP before the carbonization process were investigated by N 2 adsorption/desorption measurements at 77 K ( Figure 2). The N 2 adsorption isotherm of Py-PDT POP exhibited minimal N 2 uptake at low pressures. It rapidly increased at high pressures, indicating that Py-PDT POP could be classified as type IV, according to the IUPAC classification. This suggested the presence of mesopores in the Py-PDT POP framework, as shown in Figure 2a. Moreover, the value of the BET surface area of Py-PDT POP was calculated from the N 2 adsorption/desorption isotherm, which was 76 m 2 g −1 , with a total pore volume of 0.2 cm 3 g −1 .
The nonlocal density functional theory (NLDFT) was used to determine the pore diameters from their sorption isotherms. The pore size profile of Py-PDT POP peaked at 2.5, 5.4, and 8.8 nm, indicating that Py-PDT POP contained mesopore structures, based on the pore size ( Figure 2b). Moreover, we examined the morphology of Py-PDT POP using high-resolution transmission electron microscopy (HR-TEM) and field emission scanning electron microscopy (FE-SEM). Py-PDT POP contained aggregated particles with pores, based on the FE-SEM imaging (Figure 3a-c). SEM-EDS (energy-dispersive X-ray scattering) was used to confirm the compositions and different elements in the chemical structures of Py-PDT POP. Figure 3d-g show evidence of carbon, nitrogen, and oxygen atoms distributed in the Py-PDT POP skeleton. The HR-TEM images (Figure 3h,i) showed the existence of bright and alternating dark patches, which likely suggested that Py-PDT POP included porous networks. Moreover, we examined the morphology of Py-PDT POP using high-resolution transmission electron microscopy (HR-TEM) and field emission scanning electron microscopy (FE-SEM). Py-PDT POP contained aggregated particles with pores, based on the FE-SEM imaging (Figure 3a-c). SEM-EDS (energy-dispersive X-ray scattering) was used to confirm the compositions and different elements in the chemical structures of Py-PDT POP. Figure 3d-g show evidence of carbon, nitrogen, and oxygen atoms distributed in the Py-PDT POP skeleton. The HR-TEM images (Figure 3h,i) showed the existence of bright and alternating dark patches, which likely suggested that Py-PDT POP included porous networks.

Porosity, Thermal Stability, and Morphology of Py-PDT POP-600
As shown in Figure 4a, Py-PDT POP-600 exhibited a fast N 2 capture ability at low pressures, indicating micropores in the material. Furthermore, it continued to increase for N 2 adsorption at high pressures with a hysteresis loop, suggesting the presence of mesopores in this material. Based on the IUPAC nomenclature, the adsorption/desorption isotherm of Py-PDT POP-600 possessed both types I and type IV. The BET surface area of Py-PDT POP-600 was calculated to be 314 m 2 g −1 . The pore size distribution (PSD) of Py-PDT POP-600 was determined by applying the nonlocal density functional theory (NLDFT). The pore size distribution (PSD) curve (Figure 4b) showed that Py-PDT POP-600 possessed both micropores and mesopores (average diameters of 1.9 and 2.7 nm, respectively). Compared with the precursor Py-PDT POP, the porosity of Py-PDT POP-600 was considerably enhanced. Furthermore, we used TGA to examine the thermal stability of Py-PDT POP-600 (Figure 4c). The degradation temperature of Py-PDT POP-600 after losing 10% of its original weight was 769 • C. Moreover, the char yield for Py-PDT POP-600 was 90 wt%. The TGA results implied the outstanding thermal stability of Py-PDT POP-600; this was also attributed to the carbonization process of the as-prepared Py-PDT POP, which granted our materials sheet-like structures and, consequently, a higher stacking effect between the layers.

Porosity, Thermal Stability, and Morphology of Py-PDT POP-600
As shown in Figure 4a, Py-PDT POP-600 exhibited a fast N2 capture abilit pressures, indicating micropores in the material. Furthermore, it continued to inc N2 adsorption at high pressures with a hysteresis loop, suggesting the presence o pores in this material. Based on the IUPAC nomenclature, the adsorption/desorp therm of Py-PDT POP-600 possessed both types I and type IV. The BET surface ar PDT POP-600 was calculated to be 314 m 2 g −1 . The pore size distribution (PSD) of POP-600 was determined by applying the nonlocal density functional theory (N The pore size distribution (PSD) curve (Figure 4b) showed that Py-PDT POP-6 sessed both micropores and mesopores (average diameters of 1.9 and 2.7 nm, tively). Compared with the precursor Py-PDT POP, the porosity of Py-PDT POPconsiderably enhanced. Furthermore, we used TGA to examine the thermal sta Py-PDT POP-600 (Figure 4c). The degradation temperature of Py-PDT POP-600 a ing 10% of its original weight was 769 °C. Moreover, the char yield for Py-PDT P was 90 wt%. The TGA results implied the outstanding thermal stability of Py-PD 600; this was also attributed to the carbonization process of the as-prepared Py-PD which granted our materials sheet-like structures and, consequently, a higher effect between the layers. SEM and TEM analyses were used to examine the morphology of our porous POP-600. The SEM images of Py-PDT POP-600 revealed an aggregation and she ture (Figure 5a,b). SEM-EDS was used to confirm the compositions and different e in the chemical forms of Py-PDT POP-600. The data showed the presence of C, N atoms distributed in the Py-PDT POP-600 skeleton (Figure 5c-f). Furthermore, t images of Py-PDT POP-600 elucidated the rod-like and microporous structures 5g-i). As expected, the amorphous forms of both Py-PDT POP and Py-PDT POP-6 revealed through the XRD analysis. SEM and TEM analyses were used to examine the morphology of our porous Py-PDT POP-600. The SEM images of Py-PDT POP-600 revealed an aggregation and sheet structure (Figure 5a,b). SEM-EDS was used to confirm the compositions and different elements in the chemical forms of Py-PDT POP-600. The data showed the presence of C, N, and O atoms distributed in the Py-PDT POP-600 skeleton (Figure 5c-f). Furthermore, the TEM images of Py-PDT POP-600 elucidated the rod-like and microporous structures (Figure 5g-i). As expected, the amorphous forms of both Py-PDT POP and Py-PDT POP-600 were revealed through the XRD analysis.

CO2 Uptake Performance for Py-PDT POP and Py-PDT POP-600 at 298 K
Global warming is one of the severe consequences of industrial revolutions, so researchers continue to strive to find suitable solutions to minimize these environmental issues. As previously reported, the carbonization process at a higher temperature under N2 gas could enhance the CO2 uptake performance of the POP materials. As a result, we performed the calcination process for Py-PDT POP at 600 °C for 8 h to produce a black solid (Py-PDT POP-600), as indicated in Scheme 2b. According to the BET results, the resulting Py-PDT POP-600 material showed a larger pore volume, a higher surface area, and microporous characters compared with the pristine Py-PDT POP precursor. The CO2 isotherm measurements determined the CO2 uptake performance of Py-PDT POP and Py-PDT POP-600 at 298 K (Figure 6a). Py-PDT POP showed a low CO2 uptake of 0.24 mmol g −1 . On the other hand, Py-PDT POP-600 showed an improvement in CO2 uptake. As expected, Py-PDT POP-600, with the highest BET surface area, offered the most increased CO2 uptake of 2.7 mmol g −1 . As presented in Figure 6b, the CO2 capacity of Py-PDT POP-600 (2.7 mmol g −1 ) was higher than that of BZPh-A (1.

CO 2 Uptake Performance for Py-PDT POP and Py-PDT POP-600 at 298 K
Global warming is one of the severe consequences of industrial revolutions, so researchers continue to strive to find suitable solutions to minimize these environmental issues. As previously reported, the carbonization process at a higher temperature under N 2 gas could enhance the CO 2 uptake performance of the POP materials. As a result, we performed the calcination process for Py-PDT POP at 600 • C for 8 h to produce a black solid (Py-PDT POP-600), as indicated in Scheme 2b. According to the BET results, the resulting Py-PDT POP-600 material showed a larger pore volume, a higher surface area, and microporous characters compared with the pristine Py-PDT POP precursor. The CO 2 isotherm measurements determined the CO 2 uptake performance of Py-PDT POP and Py-PDT POP-600 at 298 K (Figure 6a). Py-PDT POP showed a low CO 2 uptake of 0.24 mmol g −1 . On the other hand, Py-PDT POP-600 showed an improvement in CO 2 uptake. As expected, Py-PDT POP-600, with the highest BET surface area, offered the most increased CO 2 uptake of 2.7 mmol g −1 . As presented in Figure 6b, the CO 2 capacity of Py-PDT POP-600 (2.7 mmol g −1 ) was higher than that

Electrochemical Performance of Py-PDT POP and Py-PDT POP-600
As mentioned above, supercapacitor-based electrodes are challengeable no these devices also consider a green energy storage methodology. Encouraged by o thesized material's physical and chemical features and carbonized form, we inve their electro-and capacitance behaviors. The electrochemical performances of our sized Py-PDT POP and Py-PDT POP-600 were estimated using cyclic voltamme and galvanostatic charge−discharge (GCD) measurements, based on a three-electr tem incorporating glassy carbon, a platinum electrode, and Hg/HgO as the w counter, and reference electrodes, respectively (Figure 7). The CV plateaus of Py-P represented numerous scans between 5 and 200 mV s −1 within a potential window to 0.0 V relative to Hg/HgO as a reference electrode. As shown in Figure 7a, Py-P could derive quasi-rectangular CV shapes in addition to palpable humbling and ha demonstrating its steady terms of the current sweep and revealing its capacitive to EDLC [41,42,61,68]. The CV plot of Py-PDT POP at a higher scan rate implied metrical quasi-rectangular shape, elucidating its EDLC nature. Conversely, Py-PD 600 (Figure 7b) showed a superior integrated rate, corresponding with a higher capacitance than pristine POP. This result was attributed to the poor electrical con ity of the pristine Py-PDT POP. The GCD measurements of Py-PDT POP and POP-600 at different current densities were investigated to evaluate their electrica itance performance. As emphasized by Figure 7c,d, the GCD plots of Py-PDT P Py-PDT POP-600 at various current densities implied a semi-triangular shape quently revealing the EDLC mechanism within their energy storage.

Electrochemical Performance of Py-PDT POP and Py-PDT POP-600
As mentioned above, supercapacitor-based electrodes are challengeable nowadays; these devices also consider a green energy storage methodology. Encouraged by our synthesized material's physical and chemical features and carbonized form, we investigated their electro-and capacitance behaviors. The electrochemical performances of our synthesized Py-PDT POP and Py-PDT POP-600 were estimated using cyclic voltammetry (CV) and galvanostatic charge−discharge (GCD) measurements, based on a three-electrode system incorporating glassy carbon, a platinum electrode, and Hg/HgO as the working, counter, and reference electrodes, respectively ( Figure 7). The CV plateaus of Py-PDT POP represented numerous scans between 5 and 200 mV s −1 within a potential window of −1.0 to 0.0 V relative to Hg/HgO as a reference electrode. As shown in Figure 7a, Py-PDT POP could derive quasi-rectangular CV shapes in addition to palpable humbling and harmony, demonstrating its steady terms of the current sweep and revealing its capacitive feature to EDLC [41,42,61,68]. The CV plot of Py-PDT POP at a higher scan rate implied a symmetrical quasi-rectangular shape, elucidating its EDLC nature. Conversely, Py-PDT POP-600 ( Figure 7b) showed a superior integrated rate, corresponding with a higher former capacitance than pristine POP. This result was attributed to the poor electrical conductivity of the pristine Py-PDT POP. The GCD measurements of Py-PDT POP and Py-PDT POP-600 at different current densities were investigated to evaluate their electrical capacitance performance. As emphasized by Figure 7c,d, the GCD plots of Py-PDT POP and Py-PDT POP-600 at various current densities implied a semi-triangular shape, consequently revealing the EDLC mechanism within their energy storage. As we expected, the specific capacitance of Py-PDT POP-600 at a current de 0.5 A g −1 was 550 F g −1 , which was considered to be much higher than Py-PDT P g −1 at 0.5 A g −1 ) (Figure 8a). We compared our Py-PDT POP-600 with other carbon materials and their derivatives, such as carbons derived from peach gum, hollow MoS2 carbon nanoplates, lignin-based and cellulose hydrogels, carbon composite licas obtained from a hybrid layered double hydroxide active container, tannic a and carbon nanotubes (CNTs), and others [61,[69][70][71][72][73][74][75][76][77][78][79][80]. The electrochemical perform our Py-PDT POP-600 displayed an excellent electrochemical character (Table S1 80]. The superb performance of Py-PDT POP-600 in energy storage applications to its high N content, surface area, pore volume, pore size, and prolonged con structure [61,68]. The long-term stability of Py-PDT POP and Py-PDT POP-600 w tigated through cycling processes for 2000 cycles at a current density of 10 A g −1 . A in Figure 8b, both Py-PDT POP and Py-PDT POP-600 showed capacitance retent and 96%, respectively. Accordingly, the Ragone plots of our materials (Figure 8c) sized that Py-PDT POP-600 possessed a maximum energy density of 76.38 Wh Kg was higher than pristine Py-PDT POP, which was 3.77 Wh Kg −1 . Electrochemica ance spectroscopy (EIS) investigations of the Py-PDT POP-and Py-PDT POP-60 electrodes helped us to emphasize their kinetic behaviors. Nyquist graphs of the POP and Py-PDT POP-600 precursors implied small semi-circles at higher frequen a semi-straight line at lower frequencies (Figure 8d). The latter represented a l sistance than the former, which revealed the lower resistance of Py-PDT POPlower resistance of Py-PDT POP-600 may have been due to the higher offering area of the electrode, consequently improving the surface wettability; hence, hanced the access of electrolyte ions to the current electrode. As we expected, the specific capacitance of Py-PDT POP-600 at a current density of 0.5 A g −1 was 550 F g −1 , which was considered to be much higher than Py-PDT POP (28 F g −1 at 0.5 A g −1 ) (Figure 8a). We compared our Py-PDT POP-600 with other carbon porous materials and their derivatives, such as carbons derived from peach gum, hollow carbon-MoS 2 carbon nanoplates, lignin-based and cellulose hydrogels, carbon composite and replicas obtained from a hybrid layered double hydroxide active container, tannic acid (TA), and carbon nanotubes (CNTs), and others [61,[69][70][71][72][73][74][75][76][77][78][79][80]. The electrochemical performance of our Py-PDT POP-600 displayed an excellent electrochemical character (Table S1) [61,[69][70][71][72][73][74][75][76][77][78][79][80]. The superb performance of Py-PDT POP-600 in energy storage applications was due to its high N content, surface area, pore volume, pore size, and prolonged conjugated structure [61,68]. The long-term stability of Py-PDT POP and Py-PDT POP-600 was investigated through cycling processes for 2000 cycles at a current density of 10 A g −1 . As shown in Figure 8b, both Py-PDT POP and Py-PDT POP-600 showed capacitance retention of 84 and 96%, respectively. Accordingly, the Ragone plots of our materials (Figure 8c) emphasized that Py-PDT POP-600 possessed a maximum energy density of 76.38 Wh Kg −1 , which was higher than pristine Py-PDT POP, which was 3.77 Wh Kg −1 . Electrochemical impedance spectroscopy (EIS) investigations of the Py-PDT POP-and Py-PDT POP-600-based electrodes helped us to emphasize their kinetic behaviors. Nyquist graphs of the Py-PDT POP and Py-PDT POP-600 precursors implied small semicircles at higher frequencies and a semi-straight line at lower frequencies (Figure 8d). The latter represented a lower resistance than the former, which revealed the lower resistance of Py-PDT POP-600. The lower resistance of Py-PDT POP-600 may have been due to the higher offering surface area of the electrode, consequently improving the surface wettability; hence, this enhanced the access of electrolyte ions to the current electrode.

Conclusions
In summary, Py-PDT POP was constructed and designed by reacting Py-Ph-4CHO with PDT-4NH 2 in DMSO at 180 • C (free metal Schiff base condensation reaction). The molecular structure and thermal stability of the building units (Py-Ph-4CHO with PDT-4NH 2 ) and the Py-PDT POP framework were carefully investigated through ssNMR, FTIR, and XPS measurements. The porosity property of Py-PDT POP was successfully enhanced through a carbonization approach at 600 • C for 8 h to access Py-PDT POP-600 as a black solid with a high surface area (314 m 2 g −1 ), high T d10 (769 • C), and high carbon residue (90 wt%), based on BET and TGA results. For the CO 2 uptake and supercapacitor applications, the as-prepared Py-PDT POP-600 showed excellent performance in CO 2 uptake (2.7 mmol g −1 at 298 K), a high specific capacitance (550 F g −1 at 0.5 A g −1 ), and retention stability (96%) compared with the Py-PDT POP framework. Therefore, the carbonization process improved the pore structure and significantly increased the POP electrochemical performance and CO 2 capture. The obtained materials and findings presented here indicated that the multifunctional Py-PDT POP-600 precursor is an excellent candidate for gas adsorption and energy storage. Creating porous Py-PDT POP-600 by linking heteroatom-rich building units may open the door to creating innovative materials for various applications, including dyes and iodine absorption.

Data Availability Statement:
The data presented in this study are available on request from the corresponding author.