Atomically Dispersed Indium Sites for Selective CO Electroreduction to Formic Acid.

An atomically dispersed structure is attractive for electrochemically converting carbon dioxide (CO) to fuels and feedstock due to its unique properties and activity. Most single-atom electrocatalysts are reported to reduce CO 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 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 CO 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 CO-to-formate process, which has a lower energy barrier than that on metallic In.