Highly Selective Electrochemical Conversion of CO₂ to HCOOH on Dendritic Indium Foams

CO 2 electrochemical reduction offers a potential technique to decrease the CO 2 emission levels, but it has been hindered by the poor performance of electrocatalysts. In this work, the electrochemical reduction of CO 2 has been studied by using a needle‐like porous indium electrode, which was electrodeposited in aqueous electrolytes containing Cl − using the hydrogen bubble dynamic template. This novel electrode displayed improved electrocatalytic activity, enhanced conversion efficiencies, and a lower onset potential −0.76 V vs. RHE), which was 0.3 V less than the indium foil electrode. Moreover, it exhibited enhanced faradaic efficiencies of 86 % for formate at −0.86 V vs. RHE and with a current density of 5.8 mA cm −2 . This excellent catalytic activity is the result of a large electrochemical surface area and needle‐like dendrite structures in the presence of Cl − salts. Utilization of the novel nanostructured electrocatalysts and understanding of the role of salts can contribute to further improvements in CO 2 reduction.