Photostability and visible-light-driven photoactivity enhancement of hierarchical C@ZnCdS/ZnS/MoS2

Abstract

Zinc cadmium sulfide solid (Zn _x Cd _1− _x S) related composites received great attention in photocatalytic hydrogen production because of their tunable bandgap and strong visible light absorption range. But sulfide-based metal materials commonly suffer from photo-corrosion issues. It is very important to construct the photocatalysts with high efficient activity and photostability for H _2 production. Herein, we successively prepared ZnCdS/ZnS (ZCS/ZS) heterostructures, ZnCdS/ZnS/MoS _2 (ZCS/ZS/M) heterostructures decorated ZCS/ZS with MoS _2 quantum dots, then we obtained x -C@ZCS/ZS and x -C@ZCS/ZS/M heterostructures encapsulated ZCS/ZS and ZCS/ZS/M with carbon layer. The performance of the photocatalytic hydrogen production showed that sample 0.05-C@ZCS/ZS/M has a remarkable photocatalytic H _2 evolution rate of 15.231 mmol·h ^−1 ·g ^−1 with noble metal-free co-catalysts. This rate was approximately 21 times higher than that of the pristine ZCS/ZS photocatalyst. The optimized sample reveals an excellent stability, without activity losses after 10 h. The improved photocatalytic activity can be attributed to the unique heterojunction structure formed by ZCS/ZS and MoS _2 . Additionally, the carbon films played a crucial role in providing excellent stability by spatially separating the sites for redox reactions, thereby inhibiting the recombination of photo-generated electron–hole pairs.

Keywords

• ZnCdS/ZnS
• MoS2
• graphitic carbon
• photostability
• hydrogen