Steering CO ₂ Electroreduction to Methane with an Atomically Precise Copper Nanocluster

Electrocatalytic reduction of CO 2 to methane is one of the effective strategies for achieving carbon cycling and addressing environmental issues. Herein, we report the successful synthesis of an atomically precise Cu 58 nanocluster. An optimized one-pot method involving sequential sodium borohydride reduction was developed. The crystal structure of the Cu 58 nanocluster belongs to the space group Pca21 and features a central distorted face-centered cubic Cu 14 kernel encapsulated within a Cu 48 S 36 P 4 shell. This shell is composed of Cu 7 S 2 and Cu 10 S 8 P 2 units and is flanked by two peripheral Cu 5 S 5 P staple motifs. ESI-MS confirms the molecular formula, and XPS analyses establish that copper exists exclusively in the Cu + oxidation state. The catalytic performance of Cu 58 was evaluated for electrochemical CO 2 reduction (CO 2 RR) upon dispersion on a C 3 N 4 support. 15-Cu 58 /C 3 N 4 achieves a CH 4 Faradaic efficiency of 73% at 600 mA cm –2 . The synergy between the topology structure of Cu 58, the Cu + sites of the nanocluster, and the pyridinic N sites of the C 3 N 4 support is identified as the key factor for enhancing CO 2 adsorption and suppressing the competing hydrogen evolution reaction, thereby steering the selectivity toward methane. This study underscores the potential of structurally defined copper nanoclusters as the premier electrocatalysts for fuel production.