Atomically Dispersed Ni–Cu Catalysts for pH‐Universal CO₂ Electroreduction

CO2 electroreduction is of great significance to reduce CO2 emissions and complete the carbon cycle. However, the unavoidable carbonate formation and low CO2 utilization efficiency in neutral or alkaline electrolytes hinder its application at commercial scale. The development of CO2 reduction under acidic conditions provides a promising strategy, but the inhibition of the hydrogen evolution reaction is difficult. Herein, the first work to design a Ni-Cu dual atom catalyst supported on hollow nitrogen-doped carbon is reported for pH-universal CO2 electroreduction to CO. The catalyst shows a high CO Faradaic efficiency of ≈99% in acidic, neutral, and alkaline electrolytes, and the partial current densities of CO reach 190 ± 11, 225 ± 10, and 489 ± 14 mA cm-2 , respectively. In particular, the CO2 utilization efficiency under acidic conditions reaches 64.3%, which is twice as high as that of alkaline conditions. Detailed study indicates the existence of electronic interaction between Ni and Cu atoms. The Cu atoms push the Ni d-band center further toward the Fermi level, thereby accelerating the formation of *COOH. In addition, operando characterizations and density functional theory calculation are used to elucidate the possible reaction mechanism of CO2 to CO under acidic and alkaline electrolytes.