Adjusting the Ratio of Oxidation States in a CuO@Cu2O for the Optimization of Electrocatalytic CO2 Conversion to Ethylene.

Understanding the impact of surface copper valence states on the distribution of electrochemical carbon dioxide products is critical. Herein, CuO@Cu2O with a Cu2+/Cu+ interface was fabricated using wet chemical etching approach. The hollow shape offered a large region for gas adsorption, while the interfacial mixed chemical state of Cu2+/Cu+ with tunable control ratio raised the local density of CHO* and accelerated the carbon-carbon coupling reaction. The H-cell test results demonstrate that, as result of this precise structural design, the Faraday efficiency of ethylene is enhanced from 15.2 % to 43.5 %, and the service life is increased 4 times. In addition, its selectivity is almost 50 % and its partial current density in MEA is 93.2 mA cm-2. In situ Raman and DFT data demonstrate that the Cu2+/Cu+ interface effect enhances the concentration of COCHO intermediates and lowers the energy barrier for the conversion of CO* to COCHO* intermediates.