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

[Display omitted] • Surface nitrogen vacancy is instrumental in the chemisorption and activation of H 2 O. • Surface nitrogen vacancy and extended photocarrier lifetime has improved H 2 production. • S-scheme band of AgI/g-C 3 N 4 is conjectured by the experiments and DFT calculations. AgI/g-C 3 N 4 S-scheme heterojunction with a unique electron transfer pathway was developed as a catalyst for H 2 evolution. We discussed the behavior of chemisorption and photoexcited charge carriers in photocatalytic reduction on the S-scheme AgI/g-C 3 N 4 heterojunction. It was demonstrated that the path of charge transfer mediated by S-scheme AgI/g-C 3 N 4 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-C 3 N 4 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-C 3 N 4 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-C 3 N 4. 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 H 2 O splitting. [ABSTRACT FROM AUTHOR]