Stably photocatalytic H2 production and selective oxidation of phenylcarbinol via regulating charge separation over NiS2/CdS under visible light

Abstract

The simultaneous development of highly efficient photocatalysts for organic oxidation and hydrogen production is crucial for sustainable energy conversion. In this study, we designed and synthesized a three-dimensional layered NiS2/CdS ohmic junction photocatalyst capable of selectively oxidizing phenylmethanol (POL) to produce benzaldehyde (BDE) under visible light, accompanied by hydrogen (H2) evolution. The NiS2/CdS composite material was characterized using SEM, TEM, XPS, and XRD. Owing to the formation of an ohmic junction, it exhibited enhanced light absorption and charge separation, which facilitated the transfer of electrons from CdS to NiS2. Photoelectrochemical and in-situ XPS analyses confirmed that the photogenerated carriers were spatially separated, with holes on CdS driving POL oxidation and electrons on NiS2 promoting H2 production. The optimal 5% NiS2/CdS achieved remarkable H2 evolution (9.31 mmol g-1 h-1) as well as the generation of BDE (9.23 mmol g-1 h-1), with a 6-fold activity enhancement over pristine CdS. Additionally, the composite demonstrated excellent stability, retaining 97.96% activity after four cycles. This work highlighted the potential of Ohmic junction photocatalysts for dual-functional redox reactions, offering a sustainable strategy for high-value chemical synthesis and clean energy production.