Grain boundary and interface interaction of metal (copper/indium) oxides to boost efficient electrocatalytic carbon...

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.