High-energy-level electron injection in ZnWO4/ZnO photocatalysts for efficient methane-to-methanol conversion

Abstract

Against the backdrop of global energy and environmental challenges, research on the photocatalytic conversion of methane to methanol has made significant progress. ZnO photocatalyst, despite its many advantages, suffers from rapid recombination of photogenerated electrons and holes in single ZnO, leading to low charge separation efficiency and thus limiting the solar energy conversion efficiency. The mixed-crystal heterostructure formed by ZnO and ZnWO₄ significantly improves photocatalytic efficiency by effectively separating and utilizing high-energy-level electrons. The conduction band of ZnWO₄ serves as an ideal “bridge” for the high-energy-level electrons generated on ZnO, enabling these electrons to quickly transfer to the conduction band of ZnWO₄, thus avoiding rapid relaxation and recombination within the conduction band of ZnO. The optimal sample achieved a methanol yield of 72 μmol/g/h, with a total carbonyl compound yield near 100 μmol/g/h, accounting for 97 % of the entire product system. This opens new avenues in the field and provides a model for the development of related composite photocatalysts, offering hope for significant breakthroughs and progress in energy conversion and utilization.