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

Electrochemical conversion of carbon dioxide (CO) 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 InO and cubic CuO have been prepared by template-assisted co-precipitation method and tested for the synthesis of syngas by electrochemical CO reduction reaction (CORR). The phases of CuO and InO are independent in bimetallic oxides and do not form any alloy oxidation phase, thus CuO and InO can maintain their crystal structure and chemical properties in bimetallic oxides. The CuO and InO would been completely reduced to metallic Cu and In during CORR. 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 H/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 CORR conversion by creating abundant grain boundaries in bimetallic oxides to regulate the ratio of H/CO.