Low-Work Function Metals Boost Selective and Fast Scission of Methanol C–H Bonds

Abstract

Photocatalytic production of chemicals and fuels with H₂ evolution has raised broad interest due to the carbon emission-free feature. In this context, selective and fast scission of methanol C–H bonds for coproduction of H₂ and ethylene glycol (EG) over metal–semiconductor composites remains to be achieved. Here, we demonstrate that indium nanoparticles (In NPs) with a low work function (<4.3 eV) increase the selectivity and activity of ZnIn₂S₄ for the scission of methanol C–H bonds. By accepting electrons from In NPs, ZnIn₂S₄ with enriched electrons tends to activate the C–H bond instead of the O–H bond. Besides, a relatively strong built-in field is formed between In NPs and the support, which facilitates photogenerated electron transfer to In NPs for H₂ evolution. Consequently, 84% selectivity of EG is obtained, and the apparent quantum yields (365 nm) of EG and H₂ reach 15.6 and 27.0%, respectively. This concept of methanol C–H bond scission boosted by low-work function metal is also proved by immobilizing In, Cd, and Bi to ZnS, resulting in up to 89% selectivity of EG.