Construction of Direct Z-Scheme Heterojunction NiFe-Layered Double Hydroxide (LDH)/Zn_0.5Cd_0.5S for Photocatalytic H₂ Evolution

It is of great significance to construct heterojunctions using industrially produced co-catalysts. The direct Z-scheme composite photocatalyst provides an effective separation of photogenerated carriers. Herein, a kind of novel 2D/3D direct Z-scheme NiFe-LDH/Zn0.5Cd0.5S is prepared. Compared with fresh catalysts, the NiFe-layered double hydroxide (LDH)/Zn0.5Cd0.5S composite exhibits advantages including excellent visible light response ability and photoelectric performance and improved H2 evolution rate by 11.6 times. Combining with theoretical calculations, ESR, XPS, and experimental results, the direct Z-scheme mechanism of the photocatalytic reaction is proposed. There is a channel for electron transfer between Zn0.5Cd0.5S and NiFe-LDH, and the electrons of Zn0.5Cd0.5S directly combine with the valence band holes of NiFe-LDH. Finally, the electrons remaining on NiFe-LDH can reduce H+ to generate H2. This process effectively achieves separation of photogenerated carriers and increases photocatalytic H2 evolution.