Efficient H2 production over CuCo2S4/g-C3N4 photocatalyst with S-scheme transfer route

It has been proven that constructing heterojunction can efficiently improve the activity of single component photocatalyst. Herein, an S-scheme CuCo2S4/g-C3N4 heterojunction was synthesized via a physical mixing strategy with a solvent evaporation process. Photocatalytic performance of the binary composites was obviously improved compared to CuCo2S4 (CCS) or g-C3N4 (CN). Under the irradiation of 300 W Xe lamp, the H2 generation rate of CCS/CN-20 reaches up to 2487 μmol g−1 h−1 in 20 vol % triethanolamine (TEOA), which is approximately 22.4- and 18-fold as those of CCS and CN, respectively. Furthermore, the H2 production of CCS/CN-20 still reaches 89 % of initial amount after 3 cycles. The significantly enhanced performance is because the unique photogenerated carrier transfer channel established between the two catalysts, which helps to generate more active sites, reduce the H2 evolution over-potential and improve the light absorption. A combination of density functional theory calculations and energy band structure analysis confirms that the electrons transfer between CCS and CN follows S-scheme pathway, which not only facilitates the spatial separation of photoexcited charges but also improves oxidation and reduction capacity. This work provides momentous reference and inspiration for the construction of highly active g-C3N4-based photocatalyst.