Electronic asymmetry of lattice oxygen sites in ZnO promotes the photocatalytic oxidative coupling of methane

Abstract

Photocatalytic oxidative coupling of methane with oxygen is promising to obtain valuable muti-carbon products, yet suffering low reactivity. Here, we apply cerium modifications on zinc oxide-supported gold catalysts based on the electronic asymmetry design of lattice oxygen to improve the coupling activity. The methane conversion rate exceeds 16000 μmol g⁻¹ h⁻¹ with muti-carbon selectivity of 94.9% and catalytic durability of 3 days, and it can increase to 34000 μmol g⁻¹ h⁻¹ under more thermal assistance, with a turnover frequency of 507 h⁻¹ for ethane and an apparent quantum efficiency of 33.7% at 350 nm. According to systematic characterizations and theoretical analysis, cerium dopants not only can boost the formation of reactive oxygen species but also intervene in the vivacity of lattice oxygen by manipulating metal-oxygen bond strength, thereby leading to favorable methyl desorption to form ethane and quick water release. This work provides insight into the rational design of efficient photocatalysts for aerobic methane-to-ethane conversion.