(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 O_V^sur-(311) facet of CeO₂ is Ce³⁺-O_V-Ce³⁺-O_L. The O_V^sur-(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.