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.