Dual-Function Reaction Center for Simultaneous Activation of CH and O via Oxygen Vacancies during Direct Selective Oxidation of CH into CHOH.

The direct oxidation of methane (CH) to methanol (CHOH) has been a focus of global concern and is quite challenging due to the thermodynamically stable CH and uncontrolled overoxidation of the products. Here, we provided a new viewpoint on the role of oxygen vacancies that induce a dual-function center in enhancing the adsorption and activation of both CH and O reactants for the subsequent selective formation of a CHOH liquid fuel on two-dimensional BiOCl photocatalysts at atmospheric pressure. The key for the favorable activity lies in the simultaneous ability of the electron-trapped Bi atom in activating CH and the formation of O radicals due to the activation of O at the adjacent oxygen vacancy site, which immediately attack the activated CH to directly produce CHOH, in initiating the oxidation reaction. What is more, the relatively low reaction barriers and the easy desorption of CHOH concertedly facilitate the highly selective conversion of CH up to 85 μmol of CHOH, with a small amount of CO and CO as the byproducts over the BiOCl nanosheets with an oxygen vacancy concentration of 2.4%. This work could broaden the avenue toward the application of oxygen-defective metal oxides in the photocatalytic selective conversion of CH to CHOH and offer a disparate perspective on the role of oxygen vacancy acting as the surface electron transfer channel in enhancing the photocatalytic performance.