Selective electrochemical reduction of CO2 to CO on CuO/In2O3 nanocomposites: role of oxygen vacancies

Abstract

Sequestration of carbon dioxide (CO₂) through electrocatalytic reduction to produce high-value industrial precursors, such as CO, is a promising avenue for sustainable development. Copper–indium is a non-noble metal catalyst with high activity towards CO production. However, there is a lack of control of parameters which enhance the selective CO production on copper–indium oxide. Here, the role of oxygen vacancy (V_O) defects in the electrochemical reduction of CO₂ (ERC) to selective CO production is reported. CuO/In₂O₃ nanocomposites with different V_O concentrations were synthesized under different synthesis environments. CuO/In₂O₃ nanocomposites prepared in an argon environment exhibited higher V_O concentrations as compared to nanocomposites prepared in an air environment. DFT calculations demonstrated that the activation barrier decreases from 0.48 eV to 0.31 eV for the nanocomposite having a higher V_O concentration, thus exhibiting a CO yield with 85% faradaic efficiency at −0.895 V vs. RHE, suggesting that V_O defects serve as the active sites for CO₂ adsorption. This study provides a novel route for the enhancement in selective ERC to CO by inducing the optimum concentration of V_O in CuO/In₂O₃ nanocomposites.