Construction of Direct Z-Scheme Heterojunction NiFe-Layered Double Hydroxide (LDH)/ZnCdS for Photocatalytic H 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/ZnCdS is prepared. Compared with fresh catalysts, the NiFe-layered double hydroxide (LDH)/ZnCdS composite exhibits advantages including excellent visible light response ability and photoelectric performance and improved H 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 ZnCdS and NiFe-LDH, and the electrons of ZnCdS directly combine with the valence band holes of NiFe-LDH. Finally, the electrons remaining on NiFe-LDH can reduce H to generate H. This process effectively achieves separation of photogenerated carriers and increases photocatalytic H evolution.