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

Electrocatalytic reduction of CO2 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 Cu58 nanocluster. An optimized one-pot method involving sequential sodium borohydride reduction was developed. The crystal structure of the Cu58 nanocluster belongs to the space group Pca21 and features a central distorted face-centered cubic Cu14 kernel encapsulated within a Cu48S36P4 shell. This shell is composed of Cu7S2 and Cu10S8P2 units and is flanked by two peripheral Cu5S5P 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 Cu58 was evaluated for electrochemical CO2 reduction (CO2RR) upon dispersion on a C3N4 support. 15-Cu58/C3N4 achieves a CH4 Faradaic efficiency of 73% at 600 mA cm–2. The synergy between the topology structure of Cu58, the Cu+ sites of the nanocluster, and the pyridinic N sites of the C3N4 support is identified as the key factor for enhancing CO2 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.