Atomic Indium Catalysts for Switching CO2 Electroreduction Products from Formate to CO.

Electrochemical reduction of CO2 to chemicals and fuels is an interesting and attractive way to mitigate greenhouse gas emissions and energy shortages. In this work, we report the use of atomic In catalysts for CO2 electroreduction to CO. The atomic In catalysts were anchored on N-doped carbon (InA/NC) through pyrolysis of In-based metal-organic frameworks (MOFs) and dicyandiamide. It was discovered that InA/NC had outstanding performance for selective CO production in the mixed electrolyte of ionic liquid/MeCN. It is different from those common In-based materials, in which formate/formic acid is formed as the main product. The faradaic efficiency (FE) of CO and total current density were 97.2% and 39.4 mA cm-2, respectively, with a turnover frequency (TOF) of ∼40 000 h-1. It is one of the highest TOF for CO production to date for all of the catalysts reported. In addition, the catalyst had remarkable stability. Detailed study indicated that InA/NC had higher double-layer capacitance, larger CO2 adsorption capacity, and lower interfacial charge transfer resistance, leading to high activity for CO2 reduction. Control experiments and theoretical calculations showed that the In-N site of InA/NC is not only beneficial for dissociation of COOH* to form CO but also hinders formate formation, leading to high selectivity toward CO instead of formate.