Synergistic Promotion Effect of ZnCoS Solid Solution and Co1–xS on Photocatalytic Hydrogen Production of the CdS Composite

Photocatalytic reactions over effective photocatalysts are attractive to explore clean hydrogen energy from water with the utilization of solar energy. Ternary Co 1– x S@ZnCoS/CdS (ZCS/CdS) composites are constructed as photocatalysts through the hydrothermal formation of Co 1– x S and ZnCoS nanoparticles on CdS nanorods. Superior to the binary Co 1– x S/CdS composite, ZCS/CdS shows the improved photocatalytic activity with a hydrogen production rate of 58.4 mmol·g –1 ·h –1, which is 31.4 and 2.1 times higher than those of CdS and Co 1– x S/CdS, respectively. Different from binary Co 1– x S/CdS, the participation of a small amount of zinc favors the formation of ZnCoS solid solution in ZCS/CdS. A synergistic promotion effect of ZnCoS and Co 1– x S is confirmed due to tight heterojunctions among Co 1– x S, ZnCoS, and CdS in ZCS/CdS. The unique heterostructure of ZCS/CdS benefits its enhanced absorption ability of visible light, accelerating the separation of photoinduced electron–hole pairs and the electron transfer. ZCS/CdS exhibits the strong reduction ability and superior photocatalytic stability due to the role of double Z-scheme electron transfer pathways in the ternary composite. This work provides a suitable way to tune noble metal-free composite photocatalysts for efficient H 2 production.