MOF-Derived Cu2O/Cu Nanospheres Anchored in Nitrogen-Doped Hollow Porous Carbon Framework for Increasing the Selectivity and Activity of Electrochemical CO2-to-Formate Conversion

Copper-based metal-organic frameworks (MOFs) and their derivatives have been used for CO2 electroreduction; however, they still have obvious drawbacks like poor selectivity and durability. Here, Cu_btc (btc = benzene-1,3,5-tricarboxylate)-derived Cu2O/Cu anchored in a nitrogen-doped porous carbon framework (Cu2O/Cu@NC) was prepared for CO2 electroreduction. Cu2O/Cu@NC-800 (carbonizing Cu_btc at 800 degrees C) produced formate and ethanol concurrently with an overpotential as low as similar to 380 mV. However, it exhibited higher selectivity toward formate against ethanol, with the maximum formate faradaic efficiencies of 70.5% at -0.68 V vs a reversible hydrogen electrode (RHE), which was 1.79 and 1.84 times higher than that of Cu2O/Cu@NC-700 and Cu2O/Cu@NC-900. This superior performance remained stable for over 30 h. The enhancement in activity and selectivity was attributed to (i) a higher Cu content and well-dispersed Cu2O/Cu nanoparticles inside the carbon frameworks, which provided abundant active reaction sites, and (ii) a higher content of N doped into the Cu2O/Cu lattice to possibly facilitate *OCHO generation. These findings provided a convenient strategy to enhance the activity and selectivity of catalysts for efficient CO2 electroreduction.