Computational Design of Copper doped Indium for electrocatalytic Reduction of CO2 to Formic Acid

Abstract Electrochemical reduction of CO 2 to formic acid is crucial to achieve a low carbon cycle and mitigate the energy crisis. Density functional calculation is deemed to be an important method for designing highly efficient catalysts for CO 2 electrochemical reduction (CO 2 ER). Cu−In alloy is mostly reported to show an increasing selectivity of reducing CO 2 to CO, however the performance of CO 2 ER over In with tiny amount of Cu doping and the influence of trace Cu to the reaction are rarely researched. Here, The CO 2 ER mechanism over In and trace Cu doped In (denoted as Cu−In) catalysts are theoretically investigated. Additionally, the relative reduction pathways and Gibbs free energies of the key intermediates ( * COOH and HCOO * ) are calculated, which show that Cu−In can produce formic acid more efficiently since Cu−In surface prefers to adsorb HCOO* to form formic acid and decrease the production of CO. Additionally, the theoretical calculation is verified by experimental results. The designed Cu−In catalyst (containing 1.55 wt % Cu) shows a high Faraday efficiency of 70 % for formate in CO 2 saturated 0.5 M NaHCO 3 electrolyte, which is much better than pure In (56 %).