ZIF-8 derived Ag/ZnO photocatalyst with enriched Ag-ZnO interface for effective oxidation of methane to liquid oxygenates with simultaneous mmol-scale productivity and ∼100 % selectivity

Achieving a high yield of oxygenates and inhibiting overoxidation remain challenging for CH 4 photooxidation. Here, we report a catalyst with enriched Ag-ZnO interfaces by using ZIF-8 as the precursor. The resulting Ag/Z-450 photocatalysts show extraordinary efficiency in the photocatalytic oxidation of CH 4 , a high liquid oxygenate yield of 57.88 mmol·g cat −1 (28.94 mmol·g cat −1 ·h −1 ) and a selectivity of ∼100 % were obtained over 3.0Ag/Z-450, with HCHO as the major product (41.04 mmol·g cat −1 , ∼71 % selectivity). Mechanistic studies revealed that ZnO and Ag species acted as electron donors and acceptors, respectively, which enhanced charge carriers transfer and separation. CH 4 and O 2 can be effectively activated to generate •CH 3 and reactive oxygen species (ROS), their following reaction led to formation of CH 3 OOH, which can be further converted to CH 3 OH and HCHO. This work contributes to the development of a “two-in-one” CH 4 photooxidation catalyst system that simultaneously achieves unparallel productivity and selectivity.