Selective Photocatalytic Oxidation of Methane to Methanol by Constructing a Rapid O<sub>2</sub> Conversion Pathway over Au–Pd/ZnO
Qiang Zhou, Xiaojie Tan, Xinyu Wang, Qinhua Zhang, Chong Qi, Hao Yang, Zhengqiu He, Tao Xing, Mingqing Wang, Mingbo Wu, Wenting Wu
Abstract
Photocatalytic oxidation of methane to methanol is an attractive process under mild conditions, nevertheless confronting significant challenges in achieving high conversion and selectivity simultaneously. Herein, we propose a strategy for the direct and rapid generation of hydroxyl radicals ( • OH) from O 2 (O 2 → *OOH → • OH) by rational design of Au–Pd/ZnO photocatalyst, skipping water-soluble H 2 O 2 and avoiding H 2 O 2 diffusion. For photocatalytic methane oxidation at ambient temperature, the yield and selectivity of CH 3 OH over the optimized 1.0% AuPd 0.5 /ZnO catalyst were as high as 81.0 μmol·h –1 and 88.2%, respectively, exceeding that of most reported systems. The formation of Au–Pd alloys could improve the O 2 adsorption and the cleavage of the O–O bond in *OOH, facilitating the efficient direct formation of • OH and increasing the CH 3 OH yield and selectivity. This work provides some guidance for the delicate design of composite photocatalysts for efficient selective photocatalytic methane oxidation and O 2 utilization.