Interstitial Zinc Defects Enriched ZnO Tuning O₂ Adsorption and Conversion Pathway for Superior Photocatalytic CH₄ Oxygenation

Abstract

Photocatalytic methane conversion into liquid oxygenates using O 2 oxidants provides a promising approach for high-value chemicals. The generation of reactive oxygen species and their reaction pathway are key to determine the oxygenate selectivity. Here, an interstitial Zn i defect ZnO (ZnO(Zn i )) is developed through thermal decomposition of the ZnO 2 precursor. Zn i favors the O 2 adsorption at a terminal adsorption configuration and induces effectively the conversion O 2 into the desired •OOH instead of •OH for improving the yield and selectivity of oxygenates. For comparison, O 2 adsorbed in a lateral configuration tends to be converted into excessive •OH on the typical Au/ZnO. As a result, ZnO(Zn i ) shows the liquid oxygenates yield of 6080 μmol g −1 with 98.6% selectivity, which leads to 10 times lower than Au/ZnO for CO 2 release of overoxidation. This work provides a pathway for O 2 adsorption and activation to regulate the photocatalytic CH 4 oxidation conversion into liquid oxygenates.