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

Abstract

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/Zn_0.5Cd_0.5S is prepared. Compared with fresh catalysts, the NiFe-layered double hydroxide (LDH)/Zn_0.5Cd_0.5S 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 Zn_0.5Cd_0.5S and NiFe-LDH, and the electrons of Zn_0.5Cd_0.5S 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.