NiCo2S4@Zn0.5Cd0.5S with direct Z-scheme heterojunction constructed by band structure adjustment of ZnxCd1-xS for efficient photocatalytic H2 evolution

Abstract

Based on hollow spherical NiCo2S4, ZnxCd1-xS with adjustable band structure was used to construct a composite for photocatalytic hydrogen evolution. The hollow spherical structure of NiCo2S4 gives ZnxCd1-xS more contact positions to form a stable heterojunction. Through the band structure adjustment for ZnxCd1-xS, the induced electron transfer model was transformed into Z-scheme, which effectively enhances the photo-produced carrier separation efficiency of the composite material. At the same time, the fast electron transfer is realized by the great conductivity of the hollow spherical NiCo2S4. This allows the composite material to obtain a shorter average lifetime of PL (0.15 ns) compared to Zn0.5Cd0.5S (3.9 ns). The composite NiCo2S4@Zn0.5Cd0.5S with Z-scheme heterojunction exhibited excellent photocatalytic HER activity and stability due to its unique spatial structure and efficient Z-scheme electron transfer path. The optimized composite NiCo2S4@Zn0.5Cd0.5S 1:1 photocatalytic HER rate reached 233.68 μmol.h−1, which is equivalent to 5.81 times that of Zn0.5Cd0.5S (40.25 μmol.h−1).