Tailoring Cu-Based Electrocatalysts for Enhanced Electrochemical CO2 Reduction to Alcohols: Structure-Selectivity Relationship

The use of CO2 as a feedstock for the production of carbon-based fuels and value-added chemicals offers a promising route toward carbon neutrality. In this study, two Cu-based electrocatalysts, namely, Cu-24/N-C and Cu-2/N-C, are successfully prepared by thermal treatment of Cu-24 metal-organic polyhedron-loaded zeolitic imidazolate framework-8 (ZIF-8) nanocrystals (Cu-24/ZIF-8) and Cu-2 dinuclear compound-loaded ZIF-8 nanocrystals (Cu-2/ZIF-8), respectively. Extensive structural and compositional analyses were conducted to confirm the formation of Cu nanocluster-loaded N-doped porous carbon supports in both Cu-24/N-C and Cu-2/N-C and Cu nanoparticles encapsulated by graphitic carbons in Cu-2/N-C as well. These two Cu-based electrocatalysts exhibited different behaviors in the electrochemical CO2 reduction reaction (CO2RR). The Cu-24/N-C electrocatalyst showed high selectivity for CO production, while Cu-2/N-C showed a preference for alcohol generation. The excellent stability of Cu-2/N-C over a 30 h continuous electrochemical reduction further highlights its potential for practical applications. The difference in electrocatalytic performance observed in the two catalysts for CO2RR was attributed to distinct catalytic sites associated with Cu nanoclusters and nanoparticles. This research reveals the significance of their structures and compositions for the development of highly selective electrocatalysts for CO2 reduction.