Tuning vacancy structures in metal-doped CeO2 nanorods to alter the reaction equilibrium of direct synthesis of dimethyl carbonate from CO2 and methanol.

Direct synthesis of dimethyl carbonate (DMC) from CO2 and methanol is thermodynamically limited, resulting in generally low DMC yields. Constructing catalysts to overcome this thermodynamic limitation is an effective strategy to enhance DMC yield. In this study, the electronic structure of oxygen vacancies and the dopant metal-oxygen vacancy-cerium local defect center (Me-Vo-Ce) active sites in cerium oxide nanorods (CeO2-R) were modulated through in-situ doping with Me (Me = Y, Sm, La), achieving a DMC space-time yield (STY) of 29.3 mmol g cat-1 h-1, which is 1.3 times higher than that of pristine CeO2-R. Fourier-transform infrared spectroscopy (FTIR) and density functional theory (DFT) calculations confirmed that the La-Vo-Ce site effectively suppresses the decomposition of the key intermediate methoxycarbonyl (MC) during the reaction, which is the primary reason for the highest turnover number (TON) of active sites observed over the La-CeO2-R catalyst. This study provides a strategy for designing CeO2-based catalysts by inhibiting the decomposition of DMC and its key functional groups, thereby driving the reaction toward DMC formation.