Dimethyl Carbonate Synthesis from CO2 over CeO2 with Electron-enriched Lattice Oxygen Specises.

The direct synthesis of dimethyl carbonate (DMC) from CO2 has both theoretical and practical value in carbon neutrality, but its efficiency is far from the application requirements due to the lacks of understanding of reaction mechanism and rational design of catalyst. Herein, abundant electron-enriched lattice oxygen species were introduced into CeO2 catalyst by constructing a large number of point defects and crystal-terminated phases in the crystal reconstruction process. Benefitting from the modulation of acid-base properties by electron-enriched lattice oxygen, a much higher DMC yield of 22.2 mmol g-1 was achieved on optimized CeO2 catalyst than other reported metal-oxide-based catalysts at similar conditions. Mechanistic investigations illustrated that the electron-enriched lattice oxygen, instead of the oxygen vacancy, not only provided abundant sites for CO2 adsorption and activation, but also significantly induced the weakly absorbed methoxy species formation. Both of which facilitated the coupling of methoxy and CO2 to *CH3OCOO intermediate. In addition, the *CH3OCOO adsorption was obviously weakened on electron-enriched lattice oxygen, thus shifting the rate-determining-step (RDS) from *CH3OCOO formation to *CH3OCOO dissociation and lowing the reaction energy barrier. This work provides insight into the underlying reaction mechanism for DMC synthesis from CO2 and methanol and the design of highly active catalysts.