Atomically Dispersed Indium Sites for Selective CO₂ Electroreduction to Formic Acid

Abstract

An atomically dispersed structure is attractive for electrochemically converting carbon dioxide (CO₂) to fuels and feedstock due to its unique properties and activity. Most single-atom electrocatalysts are reported to reduce CO₂ to carbon monoxide (CO). Herein, we develop atomically dispersed indium (In) on a nitrogen-doped carbon skeleton (In-N-C) as an efficient catalyst to produce formic acid/formate in aqueous media, reaching a turnover frequency as high as 26771 h^-1 at -0.99 V relative to a reversible hydrogen electrode (RHE). Electrochemical measurements show that trace amounts of In loaded on the carbon matrix significantly improve the electrocatalytic behavior for the CO₂ reduction reaction, outperforming conventional metallic In catalysts. Further experiments and density functional theory (DFT) calculations reveal that the formation of intermediate *OCHO on isolated In sites plays a pivotal role in the efficiency of the CO₂-to-formate process, which has a lower energy barrier than that on metallic In.