Enhanced kinetics of photocatalytic hydrogen evolution by interfacial Co-C bonded strongly coupled S-scheme inorganic perovskite/organic graphdiyne (C_nH_2n-2) heterojunction

The special intrinsic properties and structure of graphdiyne (GDY) bring new space for innovation in the field of photocatalysis. In this work, we utilized the in-situ high-temperature calcination strategy to induce the formation of Co-C chemical bonds at the interface of the catalyst and tightly bound organic GDY to inorganic perovskite CoTiO₃ to form an S-scheme heterojunction with strong coupling of chemical bonds. Co-C chemically bonded strongly coupled S-scheme heterojunctions play an active role in promoting the effective separation of photo-induced carriers, lowering the hydrogen generation potential, reducing the resistance to photo-induced electron migration, delaying the lifetime of photogenerated electrons, and enhancing the photo-reduction ability. Kelvin probe force microscopy verifies the formation of built-in electric fields at the heterojunction interface. In situ irradiation XPS to verify the formation of S-scheme heterojunctions base on DFT as a guide for the theory and photo-Tafel as an aid. The in-situ irradiation XPS in-depth study and Kelvin probe force microscopy reveals the migration path of photogenerated carriers in 20%-GCTO. Among them, the introduction of Co-C chemical bond plays the role of a high-speed transfer channel for the migration of photogenerated electrons. This work provides a new strategy for designing in situ induced interfacial covalent bond formation in S-scheme heterojunctions and constructing inorganic/organic heterojunctions.