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, Cu₂₄/N-C and Cu₂/N-C, are successfully prepared by thermal treatment of Cu₂₄ metal-organic polyhedron-loaded zeolitic imidazolate framework-8 (ZIF-8) nanocrystals (Cu₂₄/ZIF-8) and Cu₂ dinuclear compound-loaded ZIF-8 nanocrystals (Cu₂/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 Cu₂₄/N-C and Cu₂/N-C and Cu nanoparticles encapsulated by graphitic carbons in Cu₂/N-C as well. These two Cu-based electrocatalysts exhibited different behaviors in the electrochemical CO₂ reduction reaction (CO₂RR). The Cu₂₄/N-C electrocatalyst showed high selectivity for CO production, while Cu₂/N-C showed a preference for alcohol generation. The excellent stability of Cu₂/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.