In-situ synthesis of nickel/palladium bimetal/ZnIn2S4 Schottky heterojunction for efficient photocatalytic hydrogen evolution

Abstract

Coupling with bimetallic nanoparticles (NPs) has been considered as a promising strategy to enhance photocatalytic hydrogen evolution (PHE) efficiency of semiconductor photocatalysts and simultaneously minimize the use of expensive noble metals. Herein, we firstly synthesized spherical-like ZnIn2S4 (ZIS) by a solvothermal method, and then combined with nickel/palladium (denoted as NiPd) bimetallic NPs to form NiPd bimetal/ZIS Schottky heterojunction. The chemical states of NiPd NPs were confirmed in the form of NiPd bimetal rather than Ni–Pd alloy. The detailed characterization results demonstrated that the deposition of NiPd bimetal played a major role in increasing light harvesting capacity, accelerating charge carrier (electrons and holes) separation and facilitating photogenerated electrons transfer, leading to the boosted PHE performance in NiPd-ZIS photocatalysts. By adjusting Ni:Pd molar ratio in NixPdy-ZIS photocatalysts, the desired sample of Ni3Pd7-ZIS exhibited the highest PHE efficiency (106.6 µmol/h) and apparent quantum yield (AQY) value of 40.22% at 400 nm under visible light as compared to ZIS, Ni-ZIS and Pd-ZIS. The multiple techniques were performed to deeply investigate the photogenerated charge carrier separation, transfer and recombination. The possible mechanism over Ni3Pd7-ZIS sample for boosting PHE performance was presented based on characterization results. On the whole, this work would provide some insights into the development of cost-effective and high-efficiency bimetallic cocatalyst-based photocatalysts.