Anchoring Pt single atoms on specific nitrogen vacancies of carbon nitride to accelerate photogenerated carrier transfer

The anchoring sites of metal single atoms are closely related to photogenerated carrier dynamics and surface reactions. Achieving smooth photogenerated charge transfer through precise design of single-atom anchoring sites is an effective strategy to enhance the activity of photocatalytic hydrogen evolution. In this study, Pt single atoms were loaded onto ultra-thin carbon nitride with two-coordination nitrogen vacancies (V N2c -UCN-Pt) and ultra-thin carbon nitride with three-coordination nitrogen vacancies (V N3c -UCN-Pt). This paper investigated the photocatalytic hydrogen evolution performance and photogenerated carrier behavior of Pt single atoms at different anchoring sites. Surface photovoltage measurements indicated that V N2c -UCN-Pt exhibits a superior carrier separation efficiency compared to V N3c -UCN-Pt. More importantly, the surface photovoltage signal under the presence of H 2 O molecules revealed a significant decrease. Theoretical calculations suggest that V N2c -UCN-Pt exhibits superior capabilities in adsorbing and activating H 2 O molecules. Consequently, the photocatalytic hydrogen evolution efficiency of V N2c -UCN-Pt reaches 1774 µmol g −1 h −1 , which is 1.8 times that of V N3c -UCN-Pt with the same Pt loading. This work emphasized the structure–activity relationship between single-atom anchoring sites and photocatalytic activity, providing a new perspective for designing precisely dispersed single-atom sites to achieve efficient photocatalytic hydrogen evolution.