S‐Modified Graphitic Carbon Nitride with Double Defect Sites For Efficient Photocatalytic Hydrogen Evolution

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2024-12, Vol.20 (49), p.e2406576-n/a
• Main Authors: Quan, Yongkang, Li, Ruidong, Li, Xingzhou, Chen, Rongxing, Ng, Yun Hau, Huang, Jianying, Hu, Jun, Lai, Yuekun
• Format: Article
• Language: English
• Subjects: Atomic structure; Bonding strength; Carbon; Carbon nitride; charge separation; Charge transfer; Charge transport; Defects; Doping; double defect; Efficiency; Electromagnetic absorption; Electronic structure; Electrons; Hydrogen; Hydrogen evolution; Interlayers; Photocatalysis; Photocatalysts; photocatalytic hydrogen evolution; Semiconductors; Separation; Solar energy conversion; S‐doped
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202406576

Graphitic carbon nitride (gC3N4) is an attractive photocatalyst for solar energy conversion due to its unique electronic structure and chemical stability. However, gC3N4 generally suffers from insufficient light absorption and rapid compounding of photogenerated charges. The introduction of defects and atomic doping can optimize the electronic structure of gC3N4 and improve the light absorption and carrier separation efficiency. Herein, the high efficiency of carbon nitride photocatalysis for hydrogen evolution in visible light is achieved by an S‐modified double‐deficient site strategy. Defect engineering forms abundant unsaturated sites and cyano (─C≡N), which promotes strong interlayer C─N bonding interactions and accelerates charge transport in gC3N4. S doping tunes the electronic structure of the semiconductors, and the formation of C─S─C bonds optimizes the electron‐transfer paths of the C─N bonding, which enhances the absorption of visible light. Meanwhile,C≡N acts as an electron trap to capture photoexcited electrons, providing the active site for the reduction of H+ to hydrogen. The photocatalytic hydrogen evolution efficiency of SDCN (1613.5 µmol g−1 h−1) is 31.5 times higher than that of pristine MCN (51.2 µmol g−1 h−1). The charge separation situation and charge transfer mechanism of the photocatalysts are investigated in detail by a combination of experimental and theoretical calculations. Herein, the high efficiency of carbon nitride photocatalysis for hydrogen evolution in visible light is achieved by an S‐modified double‐deficient site (N‐vacancy, cyano) strategy. The cyano group acts as an electron trap to capture photoexcited electrons, providing the active site for the reduction of H+ to hydrogen. The accumulation of charge at the cyano provides a strong driving force for the directional transfer of photogenerated carriers.