本研究成功地以原型氮化碳為本體與硫氫酸鉀進行後處理，合成出具原型氮化碳—K-PHI同型異質結構的氰胺官能基修飾氮化碳光觸媒，並研究其光催化產氫之效能與利用儲存光電子能力於暗處產氫之效能。本研究於氬氣環境下，將原型氮化碳與硫氫酸鉀以重量比1:2混合後於爐館進行熱處理，合成具有不同表面形貌與結晶性的氰胺官能基修飾之氮化碳。透過FTIR、 EA確認具有氰胺官能基。透過XRD、HR-TEM與FTIR確認具有結晶相態的K-PHI。由KCN、KMACN500與KMACN400的AQY結果與UV-Vis吸收之對應關係，推論KCN與KMACN400皆為Z-scheme異質結構，而KMACN500為Type Ⅱ 異質結構。推論本研究合成之KCN、KMACN500與KMACN400皆具原型氮化碳—K-PHI同型異質結構。以KCN、KMACN500與KMACN400為光觸媒之5hr產氫量分別為20593、13823與10775 mol/g cat，於暗處3hr產氫量分別為58、37與41 mol/g cat，可以確認具有氰胺官能基團的氮化碳異質結構可提升氮化碳的產氫效能並具有儲存光電子能力。由HAADF影像推論表面活性位點的分布為影響本研究中氮化碳產氫效能之關鍵因素。

In this work, heterojunctions composed of cyanamide functional group modified Potassium Poly Heptazine Imides(K-PHI) and pristine carbon nitrides have been successfully synthesized by post-treatment of the pristine carbon nitrides with potassium thiocyanate (KSCN). The carbon nitrides photocatalysts which possess the ability of electron storage were applied to conduct photocatalytic hydrogen evolution and hydrogen evolution in the dark. The pristine carbon nitrides and KSCN were mixed at a weight ratio of 1:2 and then heated under argon atmosphere in the tube furnace to synthesize cyanamide functional group-modified nitrides with different surface morphologies and crystallinity. The cyanamide functional group was confirmed by FTIR and EA. From the XRD, HR-TEM and FTIR characterizations results, it showed the existence of crystalline phase K-PHI. From the corresponding relationship between the AQY results and UV-Vis absorption of KCN, KMACN500, and KMACN400, it is inferred that both KCN and KMACN400 are Z-scheme heterostructures and KMACN500 is a Type Ⅱ heterostructure. We proposed that the KCN, KMACN500 and KMACN400 synthesized in this study were all heterojunctions composed of K-PHI and pristine carbon nitrides. The HER yields after 5 hours irradiations of KMACN400, KMACN500 and KCN is 10775, 13823 and 20593 μmol/g-cat. The HER yields in the dark for 3 hours of KCN, KMACN500 & KMACN400 are 58, 37 and 41 μmol/g-cat. It can be confirmed that the carbon nitrides heterostructure with cyanamide functional groups improve the solar hydrogen evolution rate and possess the ability of photoelectron storage. It is deduced from the HAADF image that the distribution of surficial active sites is a key factor affecting the hydrogen evolution rate of carbon nitride in this study.

1. Lam, S.S., et al., Mainstream avenues for boosting graphitic carbon nitride efficiency: towards enhanced solar light-driven photocatalytic hydrogen production and environmental remediation. Journal of Materials Chemistry A, 2020.
2. Su, J., et al., Synthesis and application of transition metal phosphides as electrocatalyst for water splitting. Science bulletin, 2017. 62(9): p. 633-644.
3. Fujishima, A. and K. Honda, Electrochemical photolysis of water at a semiconductor electrode. nature, 1972. 238(5358): p. 37-38.
4. Fajrina, N. and M. Tahir, A critical review in strategies to improve photocatalytic water splitting towards hydrogen production. International Journal of Hydrogen Energy, 2019. 44(2): p. 540-577.
5. Su, T., et al., Role of interfaces in two-dimensional photocatalyst for water splitting. Acs Catalysis, 2018. 8(3): p. 2253-2276.
6. Lau, V.W.-h., et al., Rational design of carbon nitride photocatalysts by identification of cyanamide defects as catalytically relevant sites. Nature communications, 2016. 7: p. 12165.
7. Lau, V.W.h., et al., Dark Photocatalysis: Storage of Solar Energy in Carbon Nitride for Time‐Delayed Hydrogen Generation. Angewandte Chemie, 2017. 129(2): p. 525-529.
8. Podjaski, F., J. Kröger, and B.V. Lotsch, Toward an aqueous solar battery: direct electrochemical storage of solar energy in carbon nitrides. Advanced Materials, 2018. 30(9): p. 1705477.
9. Wang, X., et al., A metal-free polymeric photocatalyst for hydrogen production from water under visible light. Nature materials, 2009. 8(1): p. 76-80.
10. Xu, Q., et al., Enhanced visible-light photocatalytic H 2-generation activity of carbon/gC 3 N 4 nanocomposites prepared by two-step thermal treatment. Dalton Transactions, 2017. 46(32): p. 10611-10619.
11. Iqbal, W., et al., One-step large-scale highly active gC 3 N 4 nanosheets for efficient sunlight-driven photocatalytic hydrogen production. Dalton Transactions, 2017. 46(32): p. 10678-10684.
12. Li, K., F.-Y. Su, and W.-D. Zhang, Modification of g-C3N4 nanosheets by carbon quantum dots for highly efficient photocatalytic generation of hydrogen. Applied Surface Science, 2016. 375: p. 110-117.
13. Fan, Q., et al., A simple fabrication for sulfur doped graphitic carbon nitride porous rods with excellent photocatalytic activity degrading RhB dye. Applied Surface Science, 2017. 391: p. 360-368.
14. Sagara, N., et al., Photoelectrochemical CO2 reduction by a p-type boron-doped g-C3N4 electrode under visible light. Applied Catalysis B: Environmental, 2016. 192: p. 193-198.
15. Chen, P.-W., et al., Cobalt-doped graphitic carbon nitride photocatalysts with high activity for hydrogen evolution. Applied Surface Science, 2017. 392: p. 608-615.
16. Xiang, Q., J. Yu, and M. Jaroniec, Preparation and enhanced visible-light photocatalytic H2-production activity of graphene/C3N4 composites. The Journal of Physical Chemistry C, 2011. 115(15): p. 7355-7363.
17. Cheng, F., H. Yin, and Q. Xiang, Low-temperature solid-state preparation of ternary CdS/g-C3N4/CuS nanocomposites for enhanced visible-light photocatalytic H2-production activity. Applied Surface Science, 2017. 391: p. 432-439.
18. Yu, J., et al., Noble metal-free Ni (OH) 2–gC 3 N 4 composite photocatalyst with enhanced visible-light photocatalytic H 2-production activity. Catalysis Science & Technology, 2013. 3(7): p. 1782-1789.
19. Zhu, Z., et al., Fabrication of conductive and high-dispersed Ppy@ Ag/g-C3N4 composite photocatalysts for removing various pollutants in water. Applied Surface Science, 2016. 387: p. 366-374.
20. Yu, J., et al., Photocatalytic reduction of CO 2 into hydrocarbon solar fuels over gC 3 N 4–Pt nanocomposite photocatalysts. Physical Chemistry Chemical Physics, 2014. 16(23): p. 11492-11501.
21. Lei, J., et al., Highly condensed gC 3 N 4-modified TiO 2 catalysts with enhanced photodegradation performance toward acid orange 7. Journal of Materials Science, 2015. 50(9): p. 3467-3476.
22. Zhang, Z., et al., Graphitic carbon nitride nanosheet for photocatalytic hydrogen production: The impact of morphology and element composition. Applied Surface Science, 2017. 391: p. 369-375.
23. Chen, D., J. Yang, and H. Ding, Synthesis of nanoporous carbon nitride using calcium carbonate as templates with enhanced visible-light photocatalytic activity. Applied Surface Science, 2017. 391: p. 384-391.
24. Yuan, J., et al., Positioning cyanamide defects in g-C3N4: Engineering energy levels and active sites for superior photocatalytic hydrogen evolution. Applied Catalysis B: Environmental, 2018. 237: p. 24-31.
25. Zeng, Z., et al., Carbon nitride with electron storage property: Enhanced exciton dissociation for high-efficient photocatalysis. Applied Catalysis B: Environmental, 2018. 236: p. 99-106.
26. Zhu, B., et al., First-principle calculation study of tri-s-triazine-based g-C3N4: a review. Applied Catalysis B: Environmental, 2018. 224: p. 983-999.
27. He, F., et al., The nonmetal modulation of composition and morphology of g-C3N4-based photocatalysts. Applied Catalysis B: Environmental, 2020: p. 118828.
28. Ai, M., et al., MnOx-decorated 3D porous C3N4 with internal donor–acceptor motifs for efficient photocatalytic hydrogen production. Applied Catalysis B: Environmental, 2019. 256: p. 117805.
29. Jun, Y.S., et al., From melamine‐cyanuric acid supramolecular aggregates to carbon nitride hollow spheres. Advanced Functional Materials, 2013. 23(29): p. 3661-3667.
30. Jun, Y.S., et al., Three‐dimensional macroscopic assemblies of low‐dimensional carbon nitrides for enhanced hydrogen evolution. Angewandte Chemie International Edition, 2013. 52(42): p. 11083-11087.
31. Schalley, C.A., et al., Mass spectrometric characterization and gas‐phase chemistry of self‐assembling supramolecular squares and triangles. Chemistry–A European Journal, 2002. 8(15): p. 3538-3551.
32. Schlomberg, H., et al., Structural Insights into Poly (Heptazine Imides): A Light-Storing Carbon Nitride Material for Dark Photocatalysis. Chemistry of Materials, 2019. 31(18): p. 7478-7486.
33. Miller, T., et al., Carbon nitrides: synthesis and characterization of a new class of functional materials. Physical Chemistry Chemical Physics, 2017. 19(24): p. 15613-15638.
34. Zhang, G., et al., Electron deficient monomers that optimize nucleation and enhance the photocatalytic redox activity of carbon nitrides. Angewandte Chemie International Edition, 2019. 58(42): p. 14950-14954.
35. Savateev, A., et al., Towards organic zeolites and inclusion catalysts: Heptazine imide salts can exchange metal cations in the solid state. Chemistry–An Asian Journal, 2017. 12(13): p. 1517-1522.
36. Savateev, A., et al., Potassium Poly (heptazine imides) from Aminotetrazoles: Shifting Band Gaps of Carbon Nitride‐like Materials for More Efficient Solar Hydrogen and Oxygen Evolution. ChemCatChem, 2017. 9(1): p. 167-174.