Composition-Controlled CdS/ZnS Heterostructure Nanocomposites for Efficient Visible Light Photocatalytic Hydrogen Generation

To overcome the increasing energy demand worldwide, semiconductor-based photocatalytic H2 production by water splitting has gained much recognition as an alternative approach. However, the main drawbacks are lower visible light absorption and rapid recombination of photogenerated electrons–hole pairs in the semiconductor-based photocatalysts. This work reports the synthesis of CdS/ZnS heterostructures with varied compositions of each component via a single-step solvothermal method and calcination under vacuum. An optimized (CdS)0.4/(ZnS)0.6 composite exhibits the highest photocatalytic H2 generation rate of 830.95 μmol g–1 h–1, which is significantly higher than those of CdS nanorods (254.17 μmol g–1 h–1) and ZnS nanoplates (9.59 μmol g–1 h–1). The higher rate for H2 generation corresponds to better light absorption as well as efficient charge separation in the CdS/ZnS heterostructure. The photoelectrochemical study also confirms the effective charge separation in the CdS/ZnS heterostructure. Based on these results, a probable mechanism is suggested for photocatalytic H2 generation from the CdS/ZnS heterostructure.