Synergism between nitrogen vacancies and a unique electrons transfer pathway of Ag modified S-scheme g-C3N4/CdS heterojunction for efficient H2 evolution

Ag modified g-C3N4/CdS (Ag@g-C3N4/CdS) S-scheme heterojunction with a distinctive charge transfer channel was prepared as a photocatalyst for photoreduction of H2O. The effect of nitrogen vacancies and photo-excited charge carriers in the water splitting on the Ag@g-C3N4/CdS was discussed. It was found that the charge carriers transport channel in Ag@g-C3N4/CdS S-scheme heterojunction was instrumental in the enhancement of H2 production. The electrons in Ag nanospheres and in the conduction band (CB) of CdS can recombine with the holes in the valence band (VB) of g-C3N4, which prolonged the lifetime of electrons in the CB of g-C3N4. Meanwhile, a unique charge transfer channel was produced in the Ag@g-C3N4/CdS. Compared with g-C3N4, Ag@g-C3N4/CdS photocatalyst demonstrated an enhanced performance which was assigned to the increased charge carrier lifetime. The supreme Ag@g-C3N4/CdS showed photocatalytic H2 production activity up to 204.19 μmol for 4 h under illuminate ( λ ˃ 420 nm), which was 11.74 times than that of g-C3N4. • Nitrogen vacancy and prolonged electron lifetime have improved H 2 production • Surface π bond of coated g-C 3 N 4 enhances the Lewis acidity • The results of XPS are consistent with the mechanism of S-scheme heterojunction