Grain boundary and interface interaction of metal (copper/indium) oxides to boost efficient electrocatalytic carbon dioxide reduction into syngas

Electrochemical conversion of carbon dioxide (CO2) into syngas is considered a promising approach to mitigate global warming and achieve the recycling of carbon resources. In this work, a series of core–shell metal (copper/indium) oxides with abundant grain boundaries (GBs) between the amorphous In2O3 and cubic Cu2O have been prepared by template-assisted co-precipitation method and tested for the synthesis of syngas by electrochemical CO2 reduction reaction (CO2RR). The phases of Cu2O and In2O3 are independent in bimetallic oxides and do not form any alloy oxidation phase, thus Cu2O and In2O3 can maintain their crystal structure and chemical properties in bimetallic oxides. The Cu2O and In2O3 would been completely reduced to metallic Cu and In during CO2RR. The derived copper/indium possesses the maximum FE of CO (80 %) at −0.77 V vs. reversible hydrogen electrode (RHE) and a good stability of 10 h in an H-type cell. Further applied the copper/indium oxide in the MEA reactor, the FE of CO is more than 80 % at 2.6 V and the total FE of syngas is near 100 % at all applied potentials. More importantly, the H2/CO ratios can be tuned from 1/1 to 1/4 by changing the applied voltages in MEA. Therefore, this study provides a promising strategy to promote the electrocatalytic CO2RR conversion by creating abundant grain boundaries in bimetallic oxides to regulate the ratio of H2/CO.