Photothermal catalytic synthesis of DMC from CO2 and CH3OH at atmospheric pressure: Synergistic effect of surface hydroxyl groups and oxygen vacancies on spindle-like CeO2-x

The light-driven conversion of CO 2 to dimethyl carbonate (DMC) represents a promising green and sustainable pathway for achieving dual-carbon goals. However, the inherent difficulty in activating CO 2 molecules results in low DMC yields when synthesizing DMC from CO 2 and methanol (CH 3 OH) under light-driven conditions. In this study, the activation of CO 2 and CH 3 OH is enhanced by modulating the number of hydroxyl groups and the concentration of oxygen vacancies on the surface of spindle-like CeO 2-x through the introduction of cetyltrimethylammonium bromide (CTAB). Photothermal catalytic experiments show that the optimal CTAB-modified CeO 2-x achieves excellent DMC yield of 5.26 mmol·g −1 under mild conditions (0.1 MPa, 120℃). The X-ray photoelectron spectroscopy and CO 2 temperature-programmed desorption results demonstrate that CTAB modification increases the number of hydroxyl groups and oxygen vacancies on the CeO 2-x surface, which improves the effective activation of CO 2 to form the reactive intermediates such as *HCO 3 – and *CO 2 . Notably, the increased hydroxyl groups promote the dissociation of CH 3 OH into *CH 3 O. Meanwhile, isotopic labeling and in situ infrared characterization confirm the light-driven reaction pathway of CO 2 and CH 3 OH, involving the oxidation of CH 3 OH to *CH 2 OH via photogenerated holes, followed by rapid coupling with *CO 2 to generate the reactive intermediate (CH 3 OCOO*). These findings provide new insights into the rational design and construction of CeO 2 -based catalysts to achieve high yields of DMC under mild conditions.