The role of coordination-unsaturated Cu1-O3 species in the single-atom catalyst Cu/In2O3 for the preparation of acetic acid from methane and carbon dioxide

Abstract

The co-conversion of CH4 and CO2 has emerged as a challenging issue in C1 chemistry. Converting these gases into a high-value product like acetic acid is an attractive solution. In this study, we employed density-functional theory calculations to design dual-active single-atom catalysts M/In2O3 (M=Co, Ni, Cu, Zn, Rh, Pd, Ag, Cd), which incorporated oxygen vacancies. These catalysts were created by introducing metal M into the surface of In2O3 (111) through doping. Cu/In2O3, Zn/In2O3, Ag/In2O3, and Cd/In2O3 were selected based on the stability of forming single-atom catalysts. Our findings indicated that the formation of the M/In2O3 surface activates the In surface activity and significantly lowers the activation energy for methane dehydrogenation. Among them, the Cu1-O3 species on the Cu/In2O3 surface demonstrates a lower activation energy for methane dehydrogenation and C-C coupling reactions. The "H-O-C-O" hydrogenation of CH3COO* species bonded with the "n"-type structure is more realistic. Microkinetic analysis indicated that the average turnover frequency for the forming of acetic acid on the Cu/In2O3 surface is three orders of magnitude greater than that of methyl formate. This research provides theoretical support for the development of copper single-atom catalysts for the efficient conversion of CO2 and CH4 into acetic acid.