Synergism between chemisorption and unique electron transfer pathway in S-scheme AgI/g-C₃N₄ heterojunction for improving the photocatalytic H₂ evolution

AgI/g-C₃N₄ S-scheme heterojunction with a unique electron transfer pathway was developed as a catalyst for H₂ evolution. We discussed the behavior of chemisorption and photoexcited charge carriers in photocatalytic reduction on the S-scheme AgI/g-C₃N₄ heterojunction. It was demonstrated that the path of charge transfer mediated by S-scheme AgI/g-C₃N₄ heterojunction was favorable for the improvement of electron utilization in photocatalysis. The advantage of S-scheme heterojunction was that the holes in the valence band (VB) of g-C₃N₄ could recombine with the electrons in the conduction band (CB) of AgI due to the built-in electric field. Electrons on the CB of g-C₃N₄ and holes on the VB of AgI were preserved for further photocatalytic reaction. Therefore, a distinctive electron transfer pathway was introduced in the S-scheme heterojunction. In addition, the lifetime of charge carriers was prolonged, and the reduced ability of electrons was increased as compared to reference g-C₃N₄. It not only decreased the energy required for electron excitation, but also reduced the energy consumption for the charge transfer. This paper provided a new strategy to improve the utilization of photogenerated electrons and chemisorption of water for photocatalytic H₂O splitting.