Morphology and Phase Engineering of MoS2 Cocatalyst for High-Efficiency Hydrogen Evolution: One-Step Clean Synthesis and Comparative Studies

Abstract

Effective separation and transfer of photoexcited carriers are essential for photocatalysis, which could be optimized by the rational design of morphology and phase structure. Herein, using NH4HCO3 as intercalating and orienting agents, few-layer vertical-standing multiphasic MoS2 nanosheets (VM-MoS2) were successfully constructed along the longitudinal axis of CdS nanorods via a green hydrothermal method. The growth mechanism of VM-MoS2 on CdS nanorods was demonstrated to include the competitive adsorption of HCO3– and Mo7O246– anions on the protonated CdS, and the intercalation of NH4+ cations. Moreover, the impacts of the morphology and phase structure of the MoS2 cocatalyst on the photocatalytic H2 evolution (PHE) performance of CdS were carefully compared. It is found that the VM-MoS2 nanosheets can not only expose abundant active sites, but also allow the supporter to harvest the light effectively. Additionally, the metallic 1T-MoS2 in VM-MoS2 would help the interface transfer of photogenerated electrons and act as photoelectron entrepots and catalytically active sites for H2 evolution. With the VM-MoS2 cocatalyst, the as-synthesized CdS@VM-MoS2 shows an outstanding PHE rate of ∼40.1 mmol·h–1·g–1 under visible-light irradiation. Interestingly, integrating with the 2H-MoS2 phase will make the metastable 1T-MoS2 more stable, leading to the exceptional photostability of CdS@VM-MoS2 nanocomposite.