S-scheme Cu₃P/TiO₂ heterojunction for outstanding photocatalytic water splitting

TiO₂ photocatalysts are of great interest in the fields of environmental purification, new energy and so on, because of their non-toxicity, high stability, high redox ability and low cost. However, the photogenerated carriers are severely recombined, which limits the application of TiO₂ photocatalysts. Herein, S-scheme Cu₃P/TiO₂ heterojunction composites were successfully synthesized by a simple and efficient microwave hydrothermal method, and the results show that the hydrogen production rate of Cu₃P/TiO₂ is 5.83 mmol∙g^-1∙h^-1 under simulated sunlight irradiation, which is 7.3 and 83.3 times higher than that of pure TiO₂ and Cu₃P, respectively. This excellent performance is derived from the internal electric field (IEF) and energy band bending generated by the S-scheme heterojunction formed between Cu₃P and TiO₂. The density functional theory (DFT) calculation indicates that the Cu₃P possess smaller work function and more negative conduction band (CB) position than that of TiO₂, which is very conducive to greatly improve the H⁺ reduction ability and hydrogen production performance. This work provides a new idea for the reveal of electron transfer paths and active sites in S-scheme heterojunctions and deepens the mechanism understanding.