Dual-Function Reaction Center for Simultaneous Activation of CH4 and O2 via Oxygen Vacancies during Direct Selective Oxidation of CH4 into CH3OH

The direct oxidation of methane (CH 4 ) to methanol (CH 3 OH) has been a focus of global concern and is quite challenging due to the thermodynamically stable CH 4 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 4 and O 2 reactants for the subsequent selective formation of a CH 3 OH 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 4 and the formation of • O 2 – radicals due to the activation of O 2 at the adjacent oxygen vacancy site, which immediately attack the activated CH 4 to directly produce CH 3 OH, in initiating the oxidation reaction. What is more, the relatively low reaction barriers and the easy desorption of CH 3 OH concertedly facilitate the highly selective conversion of CH 4 up to 85 μmol of CH 3 OH, with a small amount of CO 2 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 4 to CH 3 OH and offer a disparate perspective on the role of oxygen vacancy acting as the surface electron transfer channel in enhancing the photocatalytic performance.