S-Scheme Heterojunction ZnCdS Nanoparticles on Layered Ni–Co Hydroxide for Photocatalytic Hydrogen Evolution

Photocatalytic hydrogen evolution technology faces great challenges in designing efficient and stable hydrogen evolution catalysts that absorb visible light. In this study, a catalyst with S-scheme heterojunction and built-in electric fields was successfully prepared by electrostatic self-assembly to load ZnCdS nanoparticles on layered Ni–Co. The ZnCdS/NiCo layered double hydroxide (NiCo-LDH) test demonstrates that the S-scheme heterojunction and built-in electric fields effectively inhibit the recombination of photogenerated electrons and holes, lowering impedance and increasing photocurrent. Additionally, more photogenerated electrons can take part in the reduction reaction, producing more H2. It is worth noting that the hydrogen evolution of ZnCdS/NiCo-LDH is 1153 μmol in 5 h, which is 10 times that of ZnCdS. We analyze the electron transport process, construction of a built-in electric field, and formation of the S-scheme of this catalyst during hydrogen evolution by in situ X-ray photoelectron spectroscopy. This study provides a new perspective for the application of ZnCdS and LDH in photocatalysis and a new direction for the breakthrough of photocatalytic hydrogen evolution research.