Metal-Organic Framework-Derived CuS Nanocages for Selective CO2 Electroreduction to Formate

Electroreduction of CO2 to target products with high activity and selectivity has techno-economic importance for renewable energy storage and CO2 utilization. Herein, we report a hierarchical CuS hollow polyhedron (CuS-HP) for electrocatalytic CO2 reduction (E-CO2R) in neutral pH aqueous media. Under E-CO2R conditions, CuS-HP undergoes structural reconstruction into sulfur-doped metallic Cu catalyst, which promotes formate production with Faradaic efficiency >90% in a wide potential range. The durability of the in situ evolved catalyst has been demonstrated by stable operation for 36 h at a formate partial current density of similar to 16 mA cm(-2) at -0.6 V versus reversible hydrogen electrode. Theoretical thermodynamic analysis reveals that the sulfur-doped Cu(111) facet is responsible for high formate selectivity by promoting formate production and suppressing hydrogen evolution.