(311) High-Index Facet of CeO2 Effectively Promotes the Synthesis of Dimethyl Carbonate from CO2 and Methanol.

The conversion of CO2 into dimethyl carbonate (DMC) is a reaction of profound environmental and economic significance and has attracted substantial attention. CeO2 stands as a promising catalyst for this reaction, with previous research mainly focused on its low-index facets. In the absence of any dehydrant, the CeO2 catalysts that merely expose low-index facets achieve a maximum DMC yield of 19.5 mmol·g-1·h-1. Herein, we reveal that the (311) high-index facet of CeO2 exhibits an improved catalytic performance compared to the low-index facets. Strikingly, with the strategic exposure of the (311) facet via a two-step hydrothermal method, the yield of DMC can reach 23.1 mmol·g-1·h-1, representing an improvement of 18.5%. According to the results of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT) calculations, we propose that the effective active structure on the OVsur-(311) facet of CeO2 is Ce3+-OV-Ce3+-OL. The OVsur-(311) facet exhibits abundant Lewis acid-base sites, as well as a unique arrangement of Ce-O, which allow more and easier adsorption and activation of CO2 and methanol. This work would attract more attention to the influence of the CeO2 high-index facet on the synthesis of DMC from CO2 and methanol.