Surface Reduced CeO2 Nanowires for Direct Conversion of CO2 and Methanol to Dimethyl Carbonate: Catalytic Performance and Role of Oxygen Vacancy

Ultralong 1D CeO2 nanowires were synthesized via an advanced solvothermal method, surface reduced under H-2 atmosphere, and first applied in direct synthesis of dimethyl carbonate (DMC) from CO2 and CH3OH. The micro morphologies, physical parameters of nanowires were fully investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), N-2 adsorption, X-ray photoelectron spectrum (XPS), and temperature-programmed desorption of ammonia/carbon dioxide (NH3-TPD/CO2-TPD). The effects of surface oxygen vacancy and acidic/alkaline sites on the catalytic activity was explored. After reduction, the acidic/alkaline sites of CeO2 nanowires can be dramatically improved and evidently raised the catalytic performance. CeO2 nanowires reduced at 500 degrees C (CeO2_NW_500) exhibited notably superior activity with DMC yield of 16.85 mmol gcat(-1). Furthermore, kinetic insights of initial rate were carried out and the apparent activation energy barrier of CeO2_NW_500 catalyst was found to be 41.9 kJ/mol, much tiny than that of CeO2_NW catalyst (74.7 KJ/mol).