Cerium coordination-dependent surface intermediates regulate activity in dimethyl carbonate synthesis from CO2 and methanol

The direct synthesis of dimethyl carbonate (DMC) from CO2 and methanol is a potential green alternative to the current industrial methods using toxic chemicals. Although many CeO2-based catalysts have been explored, the key structural factor affecting their DMC activity is still unclear. Herein, single-crystalline CeO2 catalysts bearing distinct but well-defined Ce coordination structures were examined. We found that methanol is the key species being activated by surface Ce sites (cf. CO2) to produce methyl carbonate (MC) and later DMC. The reactivity of surface methoxy species towards CO2 varies considerably with its configuration determined by Ce coordination structures. The head-to-head terminal methoxy species converts CO2 to MC faster than its atilt counterparts, resulting in a higher DMC activity. The bridging methoxy species is, however, too stable to react with CO2. The established structure-activity relation here should also guide the design of CeO2-based catalysts in other reactions involving methanol activation.