Oxygen vacancies stabilized Ag+ to enhance the performance of an Ag/In2O3 photocatalyst for non-oxidative coupling of methane

Abstract

The photocatalytic non-oxidative coupling of methane (NOCM) process is a desirable reaction that uses solar energy to convert methane into an equal proportion of ethane and hydrogen. However, most current photocatalysts suffer from low product yields and selectivity due to the over-oxidation of methane or catalyst deactivation by coke deposition. In this study, a Ag/In₂O₃ photocatalyst was synthesized by a simple deposition precipitation method for the non-oxidative coupling of methane in a batch reactor under photoirradiation at room temperature and atmospheric pressure. Ethane yields of up to 450.26 μmol g⁻¹ h⁻¹ with a high selectivity of 88% were achieved. The characterization results showed that Ag⁺ species were stably loaded in oxygen vacancies on the In₂O₃ carrier. The Ag⁺ accepted the photogenerated electrons from In₂O₃, which inhibited the recombination of the electrons and photogenerated holes, while the methane was oxidized by the holes to ethane. This study offers a new insight into the design of photocatalytic NOCM reactions.