Abstract: The higher capacity of CO₂ adsorption on the surface of magnesium oxide (MgO) with low-coordination O^2- 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.

Key words: CO₂ reduction, Photothermal catalysis, Ethanol, MgO, CuO

摘要： The higher capacity of CO₂ adsorption on the surface of magnesium oxide (MgO) with low-coordination O^2- 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.

关键词: CO₂ reduction, Photothermal catalysis, Ethanol, MgO, CuO