Enhancement of trace Ag incorporation on the Cu-Zn catalyst for CO2 hydrogenation to methanol.

The methanol synthesis from catalytic CO2 conversion has emerged as an attractive strategy for carbon valorization and sustainable energy generation. However, the catalytic efficiency of conventional Cu-Zn-based catalysts remains far from satisfactory. Herein, a Cu-Zn-Ag catalyst, synthesized via a facile co-precipitation method, exhibited a significantly improved methanol production activity compared with Cu-Zn catalysts. Notably, a trace amount of Ag doping (the Ag/Cu molar ratio was 0.001) could significantly elevate the methanol generation, with its space-time yield increasing from 258 ± 17 to 468 ± 23 gMeOH·kgcat-1·h-1, an increase of 1.82 times, while further increasing Ag doping would lead to reduced activity. Structural characterizations confirmed the Ag presence, being doped in the Cu lattice, and Ag doping was significantly beneficial to oxygen vacancy formation, which was deemed the active sites for methanol formation. The detailed reaction pathway (formate pathway) for methanol synthesis was also investigated based on density functional theory (DFT) calculations, where Ag doping lowered the energy barriers. This work elucidates the mechanism of Ag doping in Cu-Zn catalysts and provides key insights into the reaction mechanism of CO2 hydrogenation to methanol, highlighting its potential for sustainable methanol synthesis.