The Highly Selective Photocatalytic Oxidation of Cyclohexene and Ethanol Coupled with H2 Evolution over ZnCdS/Ni

Abstract

The photocatalytic production of high-value-added multi-carbon compounds and hydrogen is a green and environmentally friendly industrial production method. In this study, the highly selective oxidation of cyclohexene and ethanol was successfully achieved in the photocatalytic system through the synergistic effect of ZnCdS and Ni, with concurrent hydrogen evolution. The cyclohexene can be oxidized to 3,3′-bi(cyclohexene) with a high selectivity of 90.0%, accompanied by the release of hydrogen at a rate of 2.03 mmol·g⁻¹·h⁻¹. In the ethanol oxidation system, acetal can also be generated at a highly selective rate of 21.8 mmol·g⁻¹·h⁻¹, and the hydrogen production rate reaches up to 27.6 mmol·g⁻¹·h⁻¹. In addition, the catalytic mechanism of the highly selective oxidation coupling hydrogen evolution of these two products in different systems was proposed by the results of free radical control experiments. This study introduces a novel approach for the synthesis and broad application of noble-metal-free photocatalysts, which are suitable for the highly selective preparation of value-added multicarbon compounds coupled with hydrogen evolution.