Steering Product Selectivity with an Oxidant as the Reaction Switch for Photocatalytic CH4 Conversion over 0.5-Fe/ZnO

Abstract

Achieving highly efficient methane (CH4) photocatalytic conversion is an appealing approach for synthesizing value-added C1 liquid products but is limited by uncontrollable product selectivity. Here, we report a product selectivity steering method via an O2 switch for producing C1 liquid phase product mixture or CH3OH over 0.5-Fe/ZnO. The introduction of Fe3O4 cocatalyst in ZnO facilitates O2/H2O evolution to ·OH via O2 → ·OOH → ·OH and H2O → ·OH under the presence of O2, which then activates CH4 and produces C1 products such as CH3OH, HCHO and CH3OOH. However, under anaerobic conditions, formed ·CH3 mainly couples with ·OH from H2O and produces CH3OH. As a result, a high CH3OH yield of 1944 μmol g–1 h–1 with a selectivity of 91% is obtained at room temperature, surpassing most previously reported ZnO-based photocatalysts.