Effect of Cd Source on Photocatalytic H2 Evolution over CdS/MoS2 Composites Synthesised via a One-Pot Hydrothermal Strategy

Abstract As a prototypical non-noble metal photocatalytic composite, CdS/MoS2 has attracted increasing attention for its efficient visible-light H2 evolution. Owing to the simplicity and high reliability, the one-pot hydrothermal strategy has been widely used for CdS/MoS2 synthesis. However, Cd source effect on the hydrothermal synthesis of CdS/MoS2 composites has rarely been investigated. In this study, CdS/MoS2 is synthesised by the one-pot hydrothermal strategy using different Cd sources (CdCl2, Cd(Ac)2, Cd(NO3)2, and CdSO4), and the corresponding visible-light photocatalytic performances of resulting composites are evaluated by hydrogen evolution experiments. The results reveal that Cd source strongly influences the crystallisation, morphology, MoS2 loading, and visible-light absorption of the resulting CdS/MoS2 composites. The CdS/MoS2 composite synthesised using Cd(Ac)2 as precursor exhibited the highest hydrogen evolution rate of 19.34 mmol‧g-1‧h-1, which could be attributed to its larger specific surface area, stronger visible light absorption, and inhibited recombination of photogenerated carriers. In contrast, the use of cadmium nitrate as the Cd source hinders the formation of MoS2 because of the oxidation ability of nitrate groups in the hydrothermal process, which results in its low photocatalytic efficiency. We believe that these findings will provide guidance for the one-pot hydrothermal synthesis of CdS/MoS2 or related composites.