Selective photocatalytic oxidative coupling of methane via directional activation of oxygen over Au-loaded ZnSn-LDH with defect structure

Abstract

The selective photocatalytic oxidative coupling of methane (OCM) holds great potential in converting low-cost feedstock into C2 products. However, the challenge lies in improving the photocatalytic OCM activity through catalyst design and gaining a deeper understanding of reactant activation in the OCM process. Here, we synthesized Au-ZnSn-LDH with oxygen vacancies to achieve efficient selective oxidation of methane using O2. The optimal hybrid exhibits a C2H6 yield of 2666 μmol g−1 h−1 and 76.8 % selectivity. Our findings showed that the oxygen within the surface of ZnSn-LDH (possibly from adsorption at Ov vacancy sites) provides sites for the evolution of O2 to O2− with assistance from Au cocatalyst. More O2− could be generated from O2 provides a desired reactivity to selectively promote selective C−H activation of CH4 under photoexcitation. The Au cocatalyst plays crucial roles in facilitating the methyl transfer and promoting C−C coupling to produce C2H6 as the main product while avoiding undesirable overoxidation.