Charge migration in CdS/NiS Schottky junction composites for benzyl alcohol oxidation coupled with hydrogen production

Abstract

Photosynthesis of organic compounds coupled with enhanced hydrogen evolution is a research hotspot in energy and environmental science. Here, we fabricated CdS/NiS composites by a two-step hydrothermal method for the highly selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD) coupled with highly efficient hydrogen evolution. This efficient bifunctional catalyst promotes the separation of photoexcited electrons (e⁻) and holes (h⁺). The optimized 1% CdS/NiS composition exhibited the highest H₂ evolution rate of 6.7 mmol g⁻¹ h⁻¹ and a simultaneous BAD generation rate of 5.8 mmol g⁻¹ h⁻¹ under visible light irradiation, which are 2.5 and 3 times higher than those achieved using pure CdS, respectively. ESR measurements and DFT calculations suggested that NiS decoration promoted charge separation, thereby enhancing the efficiency of the overall photocatalytic process. This work provides an effective strategy for integrated organic synthesis and energy conversion.