One-step vulcanization of Cd(OH)Cl nanorods to synthesize CdS/ZnS/PdS nanotubes for highly efficient photocatalytic hydrogen evolution

Abstract

In this work, a novel strategy, one-step vulcanization of Cd(OH)Cl nanorods in the presence of ZnCl₂ and Na₂PdCl₄, is successfully developed to synthesize CdS/ZnS/PdS nanotubes (NTs) for the first time. In this method, the three components (CdS, ZnS and PdS) are fully combined together at the nano-scale in the CdS/ZnS/PdS NTs, creating a large number of intimate contact interfaces. As a result, the optimized CdS/ZnS/PdS NTs exhibit a significantly enhanced photocatalytic H₂ evolution rate of 1021.1 μmol h⁻¹ (10 mg of catalyst), which is 11.4 and 16.3 times higher than that of pristine CdS NTs and ZnS nanoparticles (NPs), respectively, and is the maximum reported value for CdS-based photocatalysts under similar experimental conditions. Moreover, the apparent quantum efficiency of the optimal sample can reach 26.1% at 365 nm wavelength. The improved photocatalytic performance can be attributed to the synergistic effects of the hollow tubular structure, the CdS/ZnS heterostructure and the PdS co-catalyst. Due to the hollow tubular structure, both the inner and outer surfaces of CdS/ZnS/PdS NTs can act as reaction sites to rapidly consume electrons and holes, effectively suppressing their recombination. Both the CdS/ZnS heterostructure and PdS co-catalyst can efficiently promote the separation and transfer of charge carriers. This work may provide a new method for the design and construction of new photocatalysts with highly efficient H₂ production.