Loading CuO on the surface of MgO with low-coordination basic O2− sites for effective enhanced CO2 capture and photothermal synergistic catalytic reduction of CO2 to ethanol

Abstract

The higher capacity of CO2 adsorption on the surface of magnesium oxide (MgO) with low-coordination O2− sites would effectively enhance the catalytic reduction of CO2. Herein, a series of copper oxide (CuO) and MgO composites with different mass ratios have been prepared by hydrothermal method and used for photothermal synergistic catalytic reduction of CO2 to ethanol. The catalyst with CuO mass ratio of 1.6% shows the best yield (15.17 μmol·g−1·h−1) under 3 h Xenon lamp illumination. The improved performance is attributable to the loose nano-sheet structure, uniform dispersion of active sites, the increased specific surface area, medium-strengthbasicity, the high separation efficiency of electrons and holes, and the formation of Mg−O−Cu species. The synthesized CuO and MgO composites with loose nano-sheet structure facilitate the diffusion of reactants CO2, so an excellent CO2 adsorption performance can be obtained. Meanwhile, the introduction of CuO in the form of bivalence provides higher specific surface area and porosity, thus obtaining more active sites. Moreimportantly, the Mg−O−Cu species make the donation of electrons from MgO to CO2 easier, resulting in the breaking of the old Mg-O bond and the formation of C—O bond, thus promoting the adsorption and conversion of CO2 to ethanol.