Transplanting Gold Active Sites into Non-Precious-Metal Nanoclusters for Efficient CO 2 -to-CO Electroreduction.

Electrocatalytic CO 2 reduction reaction (CO 2 RR) 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 Ni 4 nanocluster (NC). While the Ni 4 NC exclusively produces H 2 , the Au-transplanted NC selectively produces CO over H 2 . 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 CO 2 -to-CO electroreduction. The Au-transplanted NC exhibits a remarkable turnover frequency and mass activity for CO production (206 mol CO /mol NC /s and 25,228 A/g Au , respectively, at an overpotential of 0.32 V) and high durability toward the CO 2 RR over 25 h.