Photocatalytic Systems Based on Crystalline Carbon Nitride for Hydrogen Production

[1] Heterogeneous photocatalysis. From fundamentals to green applications; Colmenares, J. C.; Xu, Y.-J., Eds.; Springer-Verlag GmbH, 2016. https://doi.org/10.1007/978-3-662-48719-8

[2] Kryukov, A. I.; Stroyuk, A. L.; Kuchmii, S. Ya.; Pokhodenko V.D. Nanophotocatalysis; Akademperiodika: Kyiv, 2013.

[3] Stroyuk, O. L.; Kuchmiy, S. Ya. Semiconductor Photocatalytic Systems for the Reductive Conversion of CO2 and N2: A Review. Theor. Exp. Chem. 2018, 53, 359–386.https://doi.org/10.1007/s11237-018-9535-0

[4] Ovcharov, M. L.; Mishura, A. M.; Shvalagin, V. V.; Granchak, V.M. Semiconductor Nanocatalysts for CO2 Photoconversion Giving Organic Compounds: Design and Physicochemical Characteristics: A Review. Theor. Exp. Chem. 2019, 55, 2–28. https://doi.org/10.1007/s11237-019-09591-9

[5] Ovcharov, M. L.; Granchak, V. M. Photocatalytic Conversion of Nitrogen Oxides: Current State and Perspectives: A Review. Theor. Exp. Chem. 2021, 57, 30–63. https://doi.org/10.1007/s11237-021-09674-6

[6] Ovcharov, M. L.; Granchak, V. M. Photocatalytic Activation of Carbon Monoxide on Semiconductors and Derived Nanocomposites: Basic Principles and Mechanisms: A Review. Theor. Exp. Chem.2019, 55, 173–200. https://doi.org/10.1007/s11237-019-09608-3

[7] Ali, S. H.; Mohammed, S. S.; Al-Dokheily, M. E.; Algharagholy,L. Photocatalytic Activity of Defective TiO2-x for Water Treatment/Methyl Orange Dye Degradation. Chem. Chem. Technol. 2022, 16, 639–651. https://doi.org/10.23939/chcht16.04.639

[8] Affat, S. S.; Mohammed, S. S. Photocatalytic Degradation of Polyethylene Plastics Using MgAl2O4 Nanoparticles Prepared by Solid State Method. Chem. Chem. Technol. 2023, 17, 503–509. https://doi.org/10.23939/chcht17.03.503

[9] Stroyuk, O. L.; Kuchmiy, S. Ya. Heterogeneous Photocatalytic Selective Reductive Transformations of Organic Compounds: A Review. Theor. Exp. Chem. 2020, 56, 143–173. https://doi.org/10.1007/s11237-020-09648-0

[10] Kuchmiy, S. Ya.; Stroyuk, O. L. Selective Reductive Transformations of Organic Nitro Compounds in Heterogeneous Photocatalytic Systems: A Review. Theor. Exp. Chem. 2021, 57, 1– 29. https://doi.org/10.1007/s11237-021-09673-7

[11] Bellardita, M.; Loddo, V.; Palmisano, L. Formation of High Added Value Chemicals by Photocatalytic Treatment of Biomass. Mini-Rev. Org. Chem. 2020, 17, 884–901.https://doi.org/10.2174/1570193X17666200131112856

[12] Cheng, Q.; Yuan, Y.-J. Tang, R.; Liu, Q.-Y.; Bao, L.; Wang, P.; Zhong, J.; Zhao, Z.; Yu, Z.-T.; Zou, Z. Rapid Hydroxyl Radical Generation on (001) Facets Exposed Ultrathin Anatase TiO2 Nanosheets for Enhanced Photocatalytic Lignocelluloses-to-H2 Conversion. ACS Catal. 2022, 12, 2118–2125. https://doi.org/10.1021/acscatal.1c05713

[13] Wang, X.; Maeda, K.; Thomas A.; Takanabe K.; Xin, G.; Carlsson, J. M.; Domen, K.; Antonietti, M. A Metal-Free Polymeric Photocatalyst for Hydrogen Production from Water Under Visible Light. Nat. Mater. 2009, 8, 76−80. https://doi.org/10.1038/nmat2317

[14] Maeda, K.; Wang, X.; Nishihara, Y.; Antonietti, M.; Domen, K. Photocatalytic Activities of Graphitic Carbon Nitride Powder for Water Reduction and Oxidation under Visible Light. J. Phys. Chem. C 2009, 113, 4940−4947. https://doi.org/10.1021/jp809119m

[15] Chen, X.; Jun, Y.-S.; Takanabe, K.; Maeda, K.; Domen, K.; Fu, X.; Antonietti, M.; Wang, X. Ordered Mesoporous SBA-15 Type Graphitic Carbon Nitride: A Semiconductor Host Structure forPhotocatalytic Hydrogen Evolution with Visible Light. Chem. Mater.2009, 21, 4093–4095. https://doi.org/10.1021/cm902130z

[16] Wang, X.; Maeda, K.; Chen, X.; Takanabe, K.; Domen, K.; Hou, Y.; Fu, X.; Antonietti, M. Polymer Semiconductors for Artificial Photosynthesis: Hydrogen Evolution by Mesoporous Graphitic Carbon Nitride with Visible Light. J. Am. Chem Soc. 2009, 131, 1680–1681.https://doi.org/10.1021/ja809307s

[17] Ye, S.; Wang, R.; Wu, M.-Z.; Yuan, Y.-P. A Review on g-C3N4 for Photocatalytic Water Splitting and CO2 Reduction. Appl. Surf. Sci. 2015, 358 A, 15–27. https://doi.org/10.1016/j.apsusc.2015.08.173

[18] Wen, J.; Xie, J.; Chen, X.; Li, X. A Review on g-C3N4-Based Photocatalysts. Appl. Surf. Sci. 2017, 391, 72–123. https://doi.org/10.1016/j.apsusc.2016.07.030

[19] Stroyuk, O. L.; Raevskaya, A. E.; Kuchmy, S. Ya. Photocatalytic Hydrogen Evolution under Visible Light Illumination in Systems Based on Graphitic Carbon Nitride: A Review. Theor. Exp. Chem.2018, 54, 1–35. https://doi.org/10.1007/s11237-018-9541-2

[20] Singh, A. K.; Das, C.; Indra, A. Scope and Prospect of Transition Metal-Based Cocatalysts for Visible Light-Driven Photocatalytic Hydrogen Evolution with Graphitic Carbon Nitride. Coord. Chem.Rev. 2022, 465, 214516. https://doi.org/10.1016/j.ccr.2022.214516

[21] Hayat, A.; Syed, J. A. S.; Al-Sehemi, A. G.; El-Nasser, K. S.;Taha, T. A.; Al-Ghamdi, A. A.; Amin, M. A.; Ajmal Z.; Iqbal, W.; Palamanit, A.; et al. State of the Art Advancement in Rational Design of g-C3N4 Photocatalyst for Efficient Solar Fuel Transformation, Environmental Decontamination and Future Perspectives. Int. J. Hydrogen En. 2022, 47, 10837–10867.https://doi.org/10.1016/j.ijhydene.2021.11.252

[22] Stroyuk, A. L.; Raevskaya, A. E.; Kuchmy, S. Ya. Photocatalytic Selective Oxidation of Organic Compounds in Graphitic Carbon Nitride Systems: A Review. Theor. Exp. Chem. 2019, 55, 147–172. https://doi.org/10.1007/s11237-019-09607-4

[23] Kuchmiy, S. Ya.; Stroyuk, O. L. Photocatalytic Fixation of Molecular Nitrogen in Systems Based on Graphite-Like Carbon Nitride: A Review. Theor. Exp. Chem. 2021, 57, 85–112. https://doi.org/10.1007/s11237-021-09678-2

[24] Kuchmiy, S. Ya. Photocatalytic Air Decontamination from Volatile Organic Pollutants Using Graphite-Like Carbon Nitride: A Review. Theor. Exp. Chem. 2021, 57, 237–261. https://doi.org/10.1007/s11237-021-09693-3

[25] Wang, J.; Wang, S. A Critical Review on Graphitic Carbon Nitride (g-C3N4)-Based Materials: Preparation, Modification and Environmental Application. Coord. Chem. Rev. 2022, 453, 214338. https://doi.org/10.1016/j.ccr.2021.214338

[26] Akhundi, A.; Badiei, A.; Ziarani, G. M.; Habibi-Yangjeh, A.; Muñoz-Batista, M. J.; Luque, R. Graphitic Carbon Nitride-Based Photocatalysts: Toward Efficient Organic Transformation for Value- Added Chemicals Production. Mol. Catal. 2020, 488, 110902. https://doi.org/10.1016/j.mcat.2020.110902

[27] Kuchmiy, S. Ya. Photocatalytic Reforming of Biomass Components Using Systems Based on Graphite-Like Carbon Nitride: A Review. Theor. Exp. Chem. 2023, 59, 231–259. https://doi.org/10.1007/s11237-024-09783-y

[28] Jiang, L.; Yuan, X.; Pan, Y.; Liang, J.; Zeng, G.; Wu, Z.; Wang,H. Doping of Graphitic Carbon Nitride for Photocatalysis: A Review. Appl. Catal. B., 2017, 217, 388–406. https://doi.org/10.1016/j.apcatb.2017.06.003

[29] Patnaik, S.; Sahoo, D. P.; Parida, K. Recent Advances in Anion Doped g-C3N4 Photocatalysts: A Review. Carbon, 2020, 172, 682–711. https://doi.org/10.1016/j.carbon.2020.10.073

[30] Lee, C.-Y.; Zou, J.; Bullock, J.; Wallace G. G. Emerging Approach in Semiconductor Photocatalysis: Towards 3D Architectures for Efficient Solar Fuels Generation in Semi-Artificial Photosynthetic Systems. J. Photochem. Photobiol. C. 2019, 39, 142–160. https://doi.org/10.1016/j.jphotochemrev.2019.04.002

[31] He, F.; Wang, Z.; Li, Y.; Peng, S.; Liu B. The Nonmetal Modulation of Composition and Morphology of g-C3N4-Based Photocatalysts. Appl. Catal. B. 2020, 269, 118828. https://doi.org/10.1016/j.apcatb.2020.118828

[32] Stroyuk, O.; Raievska, O.; Zahn, D. R. T. Graphitic Carbon Nitride Nanotubes: A New Material for Emerging Applications. RSC Adv. 2020, 10, 34059–34087. https://doi.org/10.1039/D0RA05580H

[33] Li, Y.; He, Z.; Liu, L.; Jiang, Y.; Ong, W.-J.; Duan, Y.; Ho, W.;Dong, F. Inside-and-Out Modification of Graphitic Carbon Nitride (g- C3N4) Photocatalysts via Defect Engineering for Energy and Environmental Science. Nano Energy 2022, 105, 108032. https://doi.org/10.1016/j.nanoen.2022.108032

[34] Wang, W.; Shu, Z.; Liao, Z.; Zhou, J.; Meng, D.; Li, T.; Zhao, Z.; Xu L. Sustainable One-Step Synthesis of Nanostructured Potassium poly(Heptazine imide) for Highly Boosted Photocatalytic Hydrogen Evolution. Chem. Eng. J. 2021, 424, 130332. https://doi.org/10.1016/j.cej.2021.130332

[35] Lin, L.; Yu, Z.; Wang X. Crystalline Carbon Nitride Semiconductors for Photocatalytic Water Splitting. Angew. Chem. 2019, 131, 6225–6236. https://doi.org/10.1002/ange.201809897

 [36] Lin, L.; Ou, H.; Zhang, Y.; Wang, X. Tri-s-Triazine-Based Crystalline Graphitic Carbon Nitrides for Highly Efficient Hydrogen Evolution Photocatalysis. ACS Catal. 2016, 6, 3921–3931. https://doi.org/10.1021/acscatal.6b00922

[37] Song, H.; Luo, L.; Wang, S.; Zhang, G.; Jiang B. Advances in poly(Heptazine imide)/poly(triazine imide) Photocatalyst. Chin. Chem. Lett. 2024, 35, 109347.https://doi.org/10.1016/j.cclet.2023.109347

[38] He, F.; Hu, Y.; Zhong, H.; Wang, Z.; Peng, S.; Li, Y. Effect of Molten-Salt Modulation on the Composition and Structure of g-C3N4- Based Photocatalysts. Chem. Commun. 2023, 59, 10476–10487. https://doi.org/10.1039/D3CC03052K

[39] Yan, B.; Chen, Z.; Xu, Y. Amorphous and Crystalline 2D Polymeric Carbon Nitride Nanosheets for Photocatalytic Hydrogen/Oxygen Evolution and Hydrogen Peroxide Production. Chem. Asian J. 2020, 15, 2329–2340.https://doi.org/10.1002/asia.202000253

[40] Wang, S.; Zhang, J.; Bin Li, B.; Sun, H.; Wang, S. Engineered Graphitic Carbon Nitride-Based Photocatalysts for Visible-Light- Driven Water Splitting: A Review. En. Fuels 2021, 35, 6504−6526. https://doi.org/10.1021/acs.energyfuels.1c00503

[41] Liu, J.; Fu, W.; Liao, Y.; Fan, J.; Xiang, Q. Recent Advances in Crystalline Carbon Nitride for Photocatalysis. J. Mater. Sci. Technol. 2021, 91, 224–240. https://doi.org/10.1016/j.jmst.2021.03.017

[42] Zhao, B.; Zhong, W.; Chen, F.; Wang, P.; Bie, C.; Yu, H. High- Crystalline g-C3N4 Photocatalysts: Synthesis, Structure Modulation, and H2-Evolution Application. Chin. J. Catal. 2023, 52, 127–143. https://doi.org/10.1016/S1872-2067(23)64491-2

[43] Li, Y.; Ren, Z.; He, Z.; Ouyang, P.; Duan, Y.; Zhang, W.; Lv, K.; Dong, F. Crystallinity-Defect Matching Relationship of g-C3N4: Experimental and Theoretical Perspectives. Green En. Environ. 2024, 9, 623–658. https://doi.org/10.1016/j.gee.2023.02.012

[44] Li, H.; Cheng, B.; Xu, J.; Yu, J.; Cao, S. Crystalline Carbon Nitrides for Photocatalysis. EES. Catal. 2024, 2, 411–447. https://doi.org/10.1039/D3EY00302G

[45] Pu, W.; Zhou, Y.; Yang, L.; Gong, H.; Li, Y.; Yang, Q.; Zhang,D. High-Efficiency Crystalline Carbon Nitride Photocatalysts: Status and Perspectives. Nano Res. 2024, 17, 7840–7863. https://doi.org/10.1007/s12274-024-6818-83               ... 3    4

[46] Zhang, Z.; Leinenweber, K.; Bauer, V.; Garvie, L. A. J.; McMillan, P. F.; Wolf, G. H. High-Pressure Bulk Synthesis of Crystalline C6N9H .HCl: A Novel C N  Graphitic Derivative. J. Am. Chem. Soc. 2001, 123, 7788–7796. https://doi.org/10.1021/ja0103849

[47] Kroke, E.; Schwarz, M. Novel Group 14 Nitrides. Coord. Chem. Rev. 2004, 248, 493–532. https://doi.org/10.1016/j.ccr.2004.02.001

[48] Horvath-Bordon, E.; Kroke, E.; Svobod, I.; Fuess, H.; Riedel, R. Potassium Melonate, K3[C6N7(NCN)3]·5H2O, and its Potential Use for the Synthesis of Graphite-Like C3N4 Materials. New J. Chem. 2005, 29, 693–699. https://doi.org/10.1039/B416390G

[49] Sakata, Y.; Yoshimoto, K.; Kawaguchi, K.; Imamura, H.; Higashimoto S. Preparation of a Semiconductive Compound Obtained by the Pyrolysis of Urea under N2 and the Photocatalytic Property under Visible Light Irradiation. Catal. Today 2011, 161, 41–45. https://doi.org/10.1016/j.cattod.2010.09.029

[50] Long B.; Lin J.; Wang, X. Thermally-Induced Desulfurization and Conversion of Guanidine Thiocyanate into Graphitic Carbon Nitride Catalysts for Hydrogen Photosynthesis. J. Mater. Chem. A. 2014, 2, 2942–2951. https://doi.org/10.1039/C3TA14339B

[51] Zhang, H.; Yu, A. Photophysics and Photocatalysis of Carbon Nitride Synthesized at Different Temperatures. J. Phys. Chem. C 2014, 118, 11628–11635. https://doi.org/10.1021/jp503477x

[52] Wang, C.; Xiao, H.; Lu, Y.; Lv, J.; Yuan, Z.; Cheng, J. Regulation of Polymerization Kinetics to Improve Crystallinity of Carbon Nitride for Photocatalytic Eactions. ChemSusChem. 2023, 16, e202300361. https://doi.org/10.1002/cssc.202300361

[53] Iqbal, W.; Qiu, B.; Zhu, Q.; Xing, M.; Zhang, J. Self-Modified Breaking Hydrogen Bonds to Highly Crystalline Graphitic Carbon Nitrides Nanosheets for Drastically Enhanced Hydrogen Production. Appl. Catal. B 2018, 232, 306–313.https://doi.org/10.1016/j.apcatb.2018.03.072

[54] Cheng, J.; Hu, Z.; Lv, K.; Wu, X.; Li, Q.; Li, Y.; Li, X.; Sun, J.Drastic Promoting the Visible Photoreactivity of Layered Carbon Nitride by Polymerization of Dicyandiamide at High Pressure. Appl. Catal. B 2018, 232, 330–339.https://doi.org/10.1016/j.apcatb.2018.03.066

[55] Yuan, Y. P.; Yin, L. S.; Cao, S. W.; Gu, L. N.; Xu, G. S.; Du, P.;Chai, H., Liao, Y. S.; Xue, C. Microwave-Assisted Heating Synthesis: A General and Rapid Strategy for Large-Scale Production of Highly Crystalline g-C3N4 with Enhanced Photocatalytic H2 Production.Green Chem. 2014, 16, 4663–4668.https://doi.org/10.1039/C4GC01517G

[56] Guo, Y.; Li, J.; Yuan, Y.; Li, L.; Zhang, M.; Zhou, C.; Lin, Z. A. Rapid Microwave-Assisted Thermolysis Route to Highly Crystalline Carbon Nitrides for Efficient Hydrogen Generation. Angew. Chem. 2016, 128, 14913–14917. https://doi.org/10.1002/ange.201608453

[57] Li, X.-H.; Zhang, J.; Chen, X.; Fischer, A.; Thomas, A.; Antonietti, M.; Wang, X. Condensed Graphitic Carbon Nitride Nanorods by Nanoconfinement: Promotion of Crystallinity on Photocatalytic Conversion. Chem. Mater. 2011, 23, 4344-4348. https://doi.org/10.1021/cm201688v

[58] Xing, W.; Tu, W.; Han, Z.; Hu, Y.; Meng, Q.; Chen G. Template-Induced High-Crystalline g-C3N4 Nanosheets for Enhanced Photocatalytic H2 Evolution. ACS En. Lett. 2018, 3, 514-519. https://doi.org/10.1021/acsenergylett.7b01328

[59] Bhunia, M. K.; Melissen, S.; Parida, M. R.; Pradip Sarawade, P.; Basset, J.-M.; Anjum, D. H.; Mohammed, O. F.; Sautet, P.; Tangui Le Bahers, T. L.; Takanabe, K. Dendritic Tip-on Polytriazine-Based Carbon Nitride Photocatalyst with High Hydrogen Evolution Activity. Chem. Mater. 2015, 27, 8237–8247.https://doi.org/10.1021/acs.chemmater.5b02974

[60] Qiu, C.; Xu, Y.; Fan, X.; Xu, D.; Tandiana, R.; Ling, X.; Jiang, Y.; Liu, C.; Yu, L.; Chen, W.; et al. Highly Crystalline K-Intercalated Polymeric Carbon Nitride for Visible-Light Photocatalytic Alkenes and Alkynes Deuterations. Adv. Sci. 2019, 6, 1801403. https://doi.org/10.1002/advs.201801403

[61] Xu, Y.; He, X.; Zhong, H.; Singh, D. J.; Zhang, L.; Wang, R. Solid Salt Confinement Effect: An Effective Strategy to Fabricate High Crystalline Polymer Carbon Nitride for Enhanced Photocatalytic Hydrogen Evolution. Appl. Cat. B 2019, 246, 349–355. https://doi.org/10.1016/j.apcatb.2019.01.069

[62] Wang, W.; Shu, Z.; Zhou, J.; Meng, D. Alkali-Assisted Deep- Deamination to Improve the Crystallinity of poly(Heptazine imide) for Boosted Photocatalytic H2 Evolution. Separ. Purif. Technol. 2023, 318, 124027. https://doi.org/10.1016/j.seppur.2023.124027

[63] Wang, W.; Shu, Z.; Zhou, J.; Meng, D.; Zhao, Z.; Li, T. Facile Synthesis and Microstructure Modulation of Crystalline Polymeric Carbon Nitride for Highly Boosted Photocatalytic Hydrogen Evolution. J. Mater. Chem. A 2020, 8, 6785–6794. https://doi.org/10.1039/D0TA01584A

[64] Wu, X.; Ma, H.; Zhong, W.; Fan, J.; Yu, H. Porous Crystalline g- C3N4: Bifunctional NaHCO3 Template-Mediated Synthesis and Improved Photocatalytic H2 Evolution Rate. Appl. Catal. B 2020, 271, 118899. https://doi.org/10.1016/j.apcatb.2020.118899

[65] Wu X.; Ma H.; Wang K.; Wang, J.; Wang, G.; Yu, H. High- Yield and Crystalline Graphitic Carbon Nitride Photocatalyst: One- Step Sodium Acetate-Mediated Synthesis and Improved Hydrogen- Evolution Performance. J. Colloid and Interface Sci. 2022, 633, 817– 827. https://doi.org/10.1016/j.jcis.2022.11.143

[66] Xia, P.; Antonietti, M.; Zhu, B.; Heil, T.; Yu, J.; Cao, S. Designing Defective Crystalline Carbon Nitride to Enable Selective CO2 Photoreduction in the Gas Phase. Adv. Funct. Mater. 2019, 29, 1900093. https://doi.org/10.1002/adfm.201900093

[67] Bojdys, M. J.; Muller, J. O.; Antonietti, M.; Thomas, A. Ionothermal Synthesis of Crystalline, Condensed, Graphitic Carbon Nitride. Chem. 2008, 14, 8177–8182.https://doi.org/10.1002/chem.200800190

[68] Chen, X.; Li, X.; Wu, J.; Fang, C.; Ding, J.; Wan, H.; Guan G. Boosting Photocatalytic H2 Evolution by Ingenious Construction of Isotype Heptazine/Triazine Based Porous Carbon Nitride Heterojunction. Separ. Purif. Technol. 2022, 297, 121490. https://doi.org/10.1016/j.seppur.2022.121490

[69] Wirnhier, E.; Doblinger, M.; Gunzelmann, D.; Senker, J.; Lotsch, B. V.; Schnicket, W. Poly(Triazineimide) with Intercalation of Lithium and Chloride Ions [(C3N3)2(NHxLi1−x)3·LiCl]: A Crystalline 2D Carbon Nitride Network. Chem. 2011, 17, 3213–3221. https://doi.org/10.1002/chem.20100246

[70] Schwinghammer, R.; Tuffy, B.; Mesch, M. B.; Wirnhier, E.; Martineau, C.; Taulelle, F.; Schnick, W.; Senker, J.; Lotsch, B. V. Triazine-Based Carbon Nitrides for Visible-Light-Driven Hydrogen Evolution. Angew. Chem. Int. Ed. 2013, 52, 2435–2439. https://doi.org/10.1002/anie.201206817

[71] Ham, Y.; Maeda, K.; Cha, D.; Takanabe, K.; Domen, K. Synthesis and Photocatalytic Activity of poly (triazine imide). Chem. Asian J. 2013, 8, 218–224. https://doi.org/10.1002/asia.201200781

[72] He, F.; Wang, M.; Luo, L.; Wang, Z.; Peng, S.; Li, Y. Directional Modulation of Triazine and Heptazine Based Carbon Nitride for Efficient Photocatalytic H2 Evolution. Appl. Surf. Sci. 2021, 562, 150103. https://doi.org/10.1016/j.apsusc.2021.150103

[73] Li, Y.; Zhang, D.; Fan, J.; Xiang, Q. Highly Crystalline Carbon Nitride Hollow Spheres with Enhanced Photocatalytic Performance. Chin. J. Catal. 2021, 42, 627–636. https://doi.org/10.1016/S1872-2067(20)63684-1

[74] An, W.; Zhi, X.; Zhai, B.; Niu, P.; Wang, S.; Li, L. Crystallinity Improvement of poly(Heptazine imide) for High Photocatalytic Hydrogen Evolution. Scripta Mater. 2022, 221, 114992. https://doi.org/10.1016/j.scriptamat.2022.114992

[75] Wang, S.; He, F.; Lu, Y.; Wu, Y.; Zhang, Y.; Dong, P.; Liu, X.; Zhao, C.; Wang, S.; Wang, D.; et al. Enhancing Photocatalytic Hydrogen Production of Carbon Nitride: Dominant Advantage of Crystallinity over Mass Transfer. J. Colloid and Interface Sci. 2024, 654 A, 317–326. https://doi.org/10.1016/j.jcis.2023.10.046

[76] Yu, Z.; Yue, X.; Fan, J.; Xiang, Q. Crystalline Intramolecular Ternary Carbon Nitride Homojunction for Photocatalytic Hydrogen Evolution. ACS Catal. 2022, 12, 6345–6358. https://doi.org/10.1021/acscatal.2c01563

[77] Wu, Z.; Gao, H.; Yan, S.; Zou Z. Synthesis of Carbon Black/Carbon Nitride Intercalation Compound Composite for Efficient Hydrogen Production. Dalton Trans. 2014, 43, 12013–12017. https://doi.org/10.1039/C4DT00256C

[78] Jin, A.; Jia, Y.; Chen, C.; Liu, X.; Jiang, J.; Chen, X.; Zhang, F. Efficient Photocatalytic Hydrogen Evolution on Band Structure Tuned Polytriazine/Heptazine Based Carbon Nitride Heterojunctions with Ordered Needle-Like Morphology Achieved by an in situ Molten Salt Method. J. Phys. Chem. C 2017, 121, 21497–21509.https://doi.org/10.1021/acs.jpcc.7b07243

[79] Zhao, Z.; Shu, Z.; Zhou, J.; Li, T.; Yan, F.; Wang, W.; Xu, L.; Shi, L.; Liao, Z. One-Step Fabrication of Crystalline Carbon Nitride with Tunable in-Plane/Interlayer Crystallinity for Enhanced Photocatalytic Hydrogen Evolution. J. Alloys and Compounds 2022, 910, 164828. https://doi.org/10.1016/j.jallcom.2022.164828

[80] Liu, H.; Chen, D.; Wang, Z.; Jing, H.; Zhang, R. Microwave- Assisted Molten-Salt Rapid Synthesis of Isotype Triazine-/Heptazine Based g-C3N4 Heterojunctions with Highly Enhanced Photocatalytic Hydrogen Evolution Performance. Appl. Catal. B 2017, 203, 300–313. https://doi.org/10.1016/j.apcatb.2016.10.014

[81] Liu, J.; Fang, W.; Wei, Z.; Qin, Z.; Jiang, Z.; Shangguan, W. Efficient Photocatalytic Hydrogen Evolution on N-Deficient g-C3N4 Achieved by a Molten Salt Post-Treatment Approach. Appl. Catal. B 2018, 238, 465–470. https://doi.org/10.1016/j.apcatb.2018.07.021

[82] Chen, C. C.; Tsai, D. L.; Liu, H. T.; Wu J. J. Carbon Vacancy- Modified Carbon Nitride Allotropic Composite for Solar Hydrogen Generation Coupled with Selective Oxidation of 5- Hydroxymethylfurfural. ACS Sustain. Chem. Eng. 2023, 11, 6435–6444. https://doi.org/10.1021/acssuschemeng.3c00363

[83] Ren, W.; Cheng, J.; Ou, H.; Huang, C.; Titirici, M.-M.; Wang, X. Enhancing Visible-Light Hydrogen Evolution Performance of Crystalline Carbon Nitride by Defect Engineering. ChemSusChem. 2019, 12, 3257–3262. https://doi.org/10.1002/cssc.201901011

[84] Deng, P.; Liu, Y.; Shi, L.; Cui, L.; Si, W.; Yao, L. Enhanced Visible-Light H2 Evolution Performance of Nitrogen Vacancy Carbon Nitride by Improving Crystallinity. Optic Mater. 2021, 120, 111407. https://doi.org/10.1016/j.optmat.2021.111407

[85] Shao, Y.; Hao, X.; Lu, S.; Jin, Z. Molten Salt-Assisted Synthesis of Nitrogen-Vacancy Crystalline Graphitic Carbon Nitride with Tunable Band Structures for Efficient Photocatalytic Overall Water Splitting. Chem. Eng. J. 2023, 454 Part 1, 140123. https://doi.org/10.1016/j.cej.2022.140123

[86] Deng, H.; Jia, Y.; Wang, W.; Zhong, S.; Hao, R.; Fan, L.; Liu, X. Defect and Crystallinity-Mediated Charge Separation in Carbon Nitride for Synergistically Boosted Solar-Driven Hydrogen Evolution. ACS Sustain. Chem. Eng. 2023, 11, 13736–13746.https://doi.org/10.1021/acssuschemeng.3c03772

[87] Wang, Y. X.; Rao, L.; Wang, P. F.; Guo, Y.; Shi, Z. Y.; Guo, X.; Zhang, L. X. Synthesis of Nitrogen Vacancies g-C3N4 with Increased Crystallinity under the Controlling of Oxalyl Dihydrazide: Visible- Light-Driven Photocatalytic Activity. Appl. Surf. Sci. 2020, 505, 144576. https://doi.org/10.1016/j.apsusc.2019.144576

[88] Wang, W.; Kou, X.; Li, T.; Zhao, R.; Su, Y. Tunable Heptazine/Triazine Feature of Nitrogen Deficient Graphitic Carbon Nitride for Electronic Modulation and Boosting Photocatalytic Hydrogen Evolution. J. Photochem. Photobiol. A 2023, 435, 114308. https://doi.org/10.1016/j.jphotochem.2022.114308

[89] Chen, L.; Ning, S.; Liang, R.; Xia, Y.; Huang, R.; Yan, G.; Wang, X. Potassium Doped and Nitrogen Defect Modified Graphitic Carbon Nitride for Boosted Photocatalytic Hydrogen Production. Int. J. Hydrogen En. 2022, 47, 14044–14052.https://doi.org/10.1016/j.ijhydene.2022.02.147

[90] Yu, H.; Ma, H.; Wu, X.; Wang, X.; Fan, J.; Yu, J. One-Step Realization of Crystallization and Cyano-Group Generation for g- C3N4 Photocatalysts with Improved H2 Production. Sol. RRL 2020, 5, 2000372. https://doi.org/10.1002/solr.202000372

[91] Yuan, J.; X. Liu, X.; Tang, Y.; Zeng, Y.; Wang, L.; Zhang, S.; Cai, T.; Liu, Y.; Luo, S.; Pei, Y.; et al. Positioning Cyanamide Defects in g-C3N4: Engineering Energy Levels and Active Sites for Superior Photocatalytic Hydrogen Evolution. Appl. Catal. B 2018, 237, 24–31. https://doi.org/10.1016/j.apcatb.2018.05.064

[92] Deng, P.; Shi, L.; Wang, H.; Qi, W. One-Step Preparation of Novel K+ and Cyano-Group co-Doped Crystalline Polymeric Carbon Nitride with Highly Efficient H2 Evolution. Colloids and Surfaces A 2020, 601, 125023. https://doi.org/10.1016/j.colsurfa.2020.125023

[93] Zhao, B.; Gao, D.; Liu, Y.; Fan, J.; Yu, H. Cyano Group- Enriched Crystalline Graphitic Carbon Nitride Photocatalyst: Ethyl Acetate-Induced Improved Ordered Structure and Efficient Hydrogen- Evolution Activity. J. Colloid Interface Sci. 2022, 608 Part 2, 1268–1277. https://doi.org/10.1016/j.jcis.2021.10.108

[94] Yang, S.; Zhang, H.; Wang, J.; Xiang, J.; Fu, Z.; Wang, Y.; Li, Z.; Xie, H.; Tang, S.; Li, Y. Spatially Restricted Strategy to Construct Crystalline Carbon Nitride Nanosheet Assists Exciton Dissociation to Enhance Photocatalytic Hydrogen Evolution Activity. Appl. Surf. Sci. 2023, 616, 156523. https://doi.org/10.1016/j.apsusc.2023.156523

 [95] Yuan, J.; Tang, Y.; Yi, X.; Liu, C.; Li, C.; Zeng, Y.; Luo, S.Crystallization, Cyanamide Defect and Ion Induction of Carbon Nitride: Exciton Polarization Dissociation, Charge Transfer and Surface Electron Density for Enhanced Hydrogen Evolution. Appl. Catal. B 2019, 251, 206–212.https://doi.org/10.1016/j.apcatb.2019.03.069

[96] Teixeira, I. F.; Tarakina, N. V.; Silva, I. F.; López-Salas, N.; Savateev, A.; Antonietti, M. Overcoming Electron Transfer Efficiency Bottlenecks for Hydrogen Production in Highly Crystalline Carbon Nitride-Based Materials. Adv. Sustain. Syst. 2022, 6, 2100429. https://doi.org/10.1002/adsu.202100429

[97] Xu, C.; Liu, H.; Wang, D.; Li, D.; Zhang, Y.; Liu, X.; Huang, J.; Wu, S.; Fan, D.; Liu, H.; et al. Molten-Salt Assisted Synthesis of Polymeric Carbon Nitride-Based Photocatalyst for Enhanced Photocatalytic Activity under Green Light Irradiation. Appl. Catal. B 2023, 334, 122835. https://doi.org/10.1016/j.apcatb.2023.122835  

[98] Chen, Z.; Savateev, A.; Pronkin, S.; Papaefthimiou, V.; Wolff, C.; Willinger, M. G.; Willinger, E.; Neher, D.; Antonietti, M.; Dontsova, D. "The Easier the Better" Preparation of Efficient Photocatalysts-Metastable poly(Heptazine imide) Salts. Adv. Mater. 2017, 29, 1700555. https://doi.org/10.1002/adma.201700555

[99] Zhang, G.; Xu, Y.; Yan, D.; He, C.; Li, Y.; Ren, X.; Zhang, P.; Mi, H. Construction of K+ Ion Gradient in Crystalline Carbon Nitride to Accelerate Exciton Dissociation and Charge Separation for Visible Light H2 Production. ACS Catal. 2021, 11, 6995–7005. https://doi.org/10.1021/acscatal.1c00739

[100] Lin, L.; Ren, W.; Wang, C.; Asiri, A. M.; Zhang, J.; Wang, X. Crystalline Carbon Nitride Semiconductors Prepared at Different Temperatures for Photocatalytic Hydrogen Production. Appl. Cat. B 2018, 231, 234–241. https://doi.org/10.1016/j.apcatb.2018.03.009

[101] Zeng, W.; Dong, Y.; Ye, X.; Zhang, Z.; Zhang, T.; Guan, X.; Guo, L. Crystalline Carbon Nitride with in-Plane Built-in Electric Field Accelerates Carrier Separation for Excellent Photocatalytic Hydrogen Evolution. Chin. Chem. Lett. 2024, 35, 109252. https://doi.org/10.1016/j.cclet.2023.109252

[102] Xu, Y.; Shi, W.; Zhang, Y.; Tu, Z.; Sun, B.; Wang, Z.; Wang, X.; Liu, Z.; Wang, W. Realigning the Melon Chains in Carbon Nitride by Rubidium Ions to Promote Photo-Reductive Activities for Hydrogen Evolution and Environmental Remediation. J. Hazard.Mater. 2023, 453, 131435. https://doi.org/10.1016/j.jhazmat.2023.131435

[103] Xu, W.; An, X.; Zhang, Q.; Li, Z.; Zhang, Q.; Yao, Z.; Wang, X.; Wang, S.; Zheng, J.; Zhang, J.; et al. Cesium Salts as Mild Chemical Scissors to Trim Carbon Nitride for Photocatalytic H2 Evolution. ACS Sustain. Chem. Eng. 2019, 7, 12351−12357. https://doi.org/10.1021/acssuschemeng.9b01717

[104] Liao, Z.; Li, C.; Shu, Z.; Zhou, J.; Li, T.; Wang, W.; Zhao, Z.; Xu, L.; Shi, L.; Feng, L. K–Na co-Doping in Crystalline Polymeric Carbon Nitride for Highly Improved Photocatalytic Hydrogen Evolution. Int. J. Hydrogen En. 2021, 46, 26318–26328. https://doi.org/10.1016/j.ijhydene.2021.05.138

[105] Gao, H.; Yan, S.; Wang, J.; Huang, Y. A.; Wang, P.; Li, Z.; Zou, Z. Towards Efficient Solar Hydrogen Production by Intercalated Carbon Nitride Photocatalyst. Phys. Chem. Chem. Phys. 2013. 15, 18077–18084. https://doi.org/10.1039/C3CP53774A

[106] Zhang, G.; Xu, Y.; Rauf, M.; Zhu, J.; Li, Y.; He, C.; Ren, X.; Zhang, P.; Mi, H. Breaking the Limitation of Elevated Coulomb Interaction in Crystalline Carbon Nitride for Visible And Near- Infrared Light Photoactivity. Adv. Sci. 2022, 9, 2201677. https://doi.org/10.1002/advs.202201677

[107] Sahoo, S. K.; Teixeira, I. F.; Naik, A.; Heske, J.; Cruz, D.; Antonietti, M.; Savateev, A.; Kühne, T. D. Photocatalytic Water Splitting Reaction Catalyzed by Ion-Exchanged Salts of Potassium poly(Heptazine imide) 2D Materials. J. Phys. Chem. C. 2021, 125, 13749–13758. https://doi.org/10.1021/acs.jpcc.1c03947

[108] Grodzyuk G. Ya.; Koryakina K. V.; Shvalagin V. V.; Korzhak, G.V.; Kuchmiy, S.Y. Photocatalytic Evolution of Hydrogen from Alcohol–Aqueous Solutions Using Nanocrystalline Carbon Nitride Modified with Magnesium Chloride under the Visible Light Irradiation. Theor. Exp. Chem. 2022, 58, 198–204. https://doi.org/10.1007/s11237-022-09736-3

[109] Wang, Y.; Zhou, X.; Xu, W.; Sun, Y.; Wang, T.; Zhang, Y.; Dong, J.; Hou, W.; Wu, N.; Wu, L.; et al. Zn-Doped Tri-S-Triazine Crystalline Carbon Nitrides for Efficient Hydrogen Evolution Photocatalysis. Appl. Catal. A 2019, 582, 117118. https://doi.org/10.1016/j.apcata.2019.117118

[110] Wu, Y.; Xu, W.; W, N.; Wang, Z.; Wang, Y.; Zhang, Y.; Zhong, W.; Cai, H. L.; Wu, X. S. Bridging and Bonding: Zinc and Potassium co-Assisted Crystalline g-C3N4 for Significant Highly Efficient upon Photocatalytic Hydrogen Evolution. Appl. Surf. Sci. 2021, 542, 148620. https://doi.org/10.1016/j.apsusc.2020.148620

[111] Shi, W.; Cao, L.; Shi, Y.; Zhong, W.; Chen, Z.; Wei, Y.; Guo, F.; Chen, L.; Du, X. Boosted Built-in Electric Field and Active Sites Based on Ni-Doped Heptazine/Triazine Crystalline Carbon Nitride for Achieving High-Efficient Photocatalytic H2 Evolution. J. Mol. Str.2023, 1280, 135076. https://doi.org/10.1016/j.molstruc.2023.135076

[112] Wang Y.; Xie D.; Wang G.; Wu, Y.; Shi, R.; Zhou, C.; Meng, X.; Zhang, T. Single-Atomic Co-N4-O Site Boosting Exciton Dissociation and Hole Extraction for Improved Photocatalytic Hydrogen Evolution in Crystalline Carbon Nitride. Nano En. 2022, 104, Part A, 107938. https://doi.org/10.1016/j.nanoen.2022.107938

[113] Xu, T.; Xia, Z.; Li, H.; Niu, P.; Wang, S.; Li, L. Constructing Crystalline g-C3N4/g-C3N4−xSx Isotype Heterostructure for Efficient Photocatalytic and Piezocatalytic Performances. En. Environ. Mater. 2023, 6, e12306. https://doi.org/10.1002/eem2.12306

[114] Ovcharov, M. L.; Glukhova, P. I.; Korzhak, G. V.; Kutsenko, O. S.; Stara, T. R.; Kuchmiy, S. Ya. Influence of Sulfur Doping of Crys- talline Carbon Nitride on Photocatalytic Hydrogen Evolution from Alcohol–Aqueous Solutions under Visible Light. Theor. Exp. Chem. 2024, 59, 397–405. https://doi.org/10.1007/s11237-024-09798-5

[115] Stara, T.; Kutsenko, A.; Korzhak, H.; Ovcharov, M.; Kuchmiy, S. Photocatalytic Activity of Boron-Doped Bulk and Crystalline Graphitic Carbon Nitride in Visible Light-Driven Hydrogen Production. Chem. Chem. Technol. 2024, 18, 449–457. https://doi.org/10.23939/chcht18.04.449

[116] Wang, Y.; Zhou, J.; Wang, F.; Xie, Y.; Liu, S.; Ao, Z.; Li, C. Hydrogen Generation from Photocatalytic Treatment of Wastewater Containing Pharmaceuticals and Personal Care Products by Oxygen- Doped Crystalline Carbon Nitride. Separ. Purif. Technol. 2022, 296, 121425. https://doi.org/10.1016/j.seppur.2022.121425

[117] Li, J.; Liu, X.; Che, H.; Liu, C.; Li, C. Facile Construction of O- Doped Crystalline/Non-Crystalline g-C3N4 Embedded Nano- Homojunction for Efficiently Photocatalytic H2 Evolution. Carbon 2021, 172, 602–612. https://doi.org/10.1016/j.carbon.2020.10.051

[118] Zhang, G.; Xu, Y.; He, C.; Zhang, P.; Mi, H. Oxygen-Doped Crystalline Carbon Nitride with Greatly Extended Visible-Light- Responsive Range for Photocatalytic H2 Generation. Appl. Catal. B 2021, 283, 119636. https://doi.org/10.1016/j.apcatb.2020.119636

[119] Xu, Y.; Fan, M.; Yang, W.; Xiao, Y.; Zeng, L.; Wu, X.; Xu, Q.; Su, C.; He, Q. Homogeneous Carbon/Potassium‐Incorporation Strategy for Synthesizing Red Polymeric Carbon Nitride Capable of Near-Infrared Photocatalytic H2 Production. Adv. Mater. 2021, 33, 2101455. https://doi.org/10.1002/adma.202101455

[120] Cui, Y.; Li, X.; Yang, C.; Xiao, B.; Xu, H. K–I co-Doped Crystalline Carbon Nitride with Outstanding Visible Light Photocatalytic Activity for H2 Evolution. Int. J. Hydrogen En. 2022, 47, 12569–12581. https://doi.org/10.1016/j.ijhydene.2022.02.005