Transplanting Gold Active Sites into Non-Precious-Metal Nanoclusters for Efficient CO₂-to-CO Electroreduction

Electrocatalytic CO2 reduction reaction (CO2RR) is greatly facilitated by Au surfaces. However, large fractions of underlying Au atoms are generally unused during the catalytic reaction, which limits mass activity. Herein, we report a strategy for preparing efficient electrocatalysts with high mass activities by the atomic-level transplantation of Au active sites into a Ni4 nanocluster (NC). While the Ni4 NC exclusively produces H2, the Au-transplanted NC selectively produces CO over H2. The origin of the contrasting selectivity observed for this NC is investigated by combining operando and theoretical studies, which reveal that while the Ni sites are almost completely blocked by the CO intermediate in both NCs, the Au sites act as active sites for CO2-to-CO electroreduction. The Au-transplanted NC exhibits a remarkable turnover frequency and mass activity for CO production (206 molCO/molNC/s and 25,228 A/gAu, respectively, at an overpotential of 0.32 V) and high durability toward the CO2RR over 25 h.