Surface engineering of CexBi1−xO2−δ nanorods rich in oxygen vacancies for enhancing photo-thermal synthesis of dimethyl carbonate from CO2/CH3OH

Abstract

The utilization of oxygen vacancies to modulate the surface properties of catalysts is a powerful way to enhance catalytic activity. In this work, the doping effect of Bi3+ on the performance of CeO2−δ (CexBi1−xO2−δ) hybrid nanorods with rich oxygen vacancies for the photo-thermal synthesis of dimethyl carbonate (DMC) from CO2/CH3OH (140 ℃, 1.6 MPa, 4 h) is systematically investigated. It is found that Ce0.9Bi0.1O2−δ exhibits the best catalytic performance, achieving a photo-thermal yield of 3.13 mmol∙g−1 without any dehydrating agent (1.14 times compared to thermal catalysis). It turns out that regulating the concentration of Bi3+ ions not only modifies the oxygen vacancy content, but also improves the light harvesting efficiency. Moreover, a series of characterization techniques, such as X-ray photoelectron spectroscopy, Raman spectrometer and electron paramagnetic resonance are employed to analyze and verify that the asymmetric oxygen vacancies are conducive to the improvement in the CO2 adsorption-activation. Finally, a possible reaction mechanism model of Bi3+ doping on CeO2−δ for the photo-thermal synthesis of DMC from CO2 and CH3OH is proposed. This work provides a practical approach to catalyst surface engineering design.