Three-Dimensional Hierarchical Copper-Based Nanostructures as Advanced Electrocatalysts for CO₂ Reduction

Cu-based nanomaterials have received increasing interest for electrocatalytic applications in the CO2 reduction reaction. However, it is challenging to design nanostructured Cu electrodes to improve both the chemical kinetics and molecular transport under the reaction conditions. Here we report on a new type of three-dimensional Cu-based nanostructures as advanced electrocatalysts for CO2 reduction. Driven by thermal oxidation, CuO nanowires and/or porous nanostructures are grown on commercial Cu foams with three-dimensional (3D) frameworks. An electrochemical method is used to reduce CuO to Cu with the structural features largely preserved. The derived Cu-based hierarchical nanostructures demonstrate high catalytic activity and selectivity for CO2 reduction, achieving >80% Faradaic efficiency and ∼3 times enhancement in terms of CO2 conversion rate as compared to the Cu nanowires grown on planar electrodes. Our work highlights the great potential of 3D Cu nanostructures for improving the energy efficiency and power performance of CO2 electrolysis.