High Dispersion of Copper Nanoparticles on Carbon Black in Minimal Loadings Enhances the Electroreduction of CO to CO.

Electrochemical CO₂ reduction (ECR) offers a promising route for converting CO₂ emissions into valuable chemicals. To enhance economic viability, the development of efficient and low-cost catalysts based on nonnoble metals is crucial. This study focuses on copper (Cu) nanoparticles highly dispersed on a carbon black (CB) support, synthesized via a solvothermal method that allows for precise control over particle size and loading. We demonstrate that tuning these properties is essential to steer the selectivity of CO₂ reduction toward carbon monoxide (CO). Notably, a low catalyst loading of only 0.159 mg/cm was sufficient to achieve high performance. The optimized catalyst delivered a CO partial current density of 66 mA/cm (total current density of 100 mA/cm with 66% Faradaic efficiency (FE) for CO) at a cell voltage of 3.2 V. Furthermore, our results highlight the critical role of the gas diffusion layer (GDL), showing that its composition significantly impacts catalyst activity. This underscores the necessity of engineering advanced GDLs with tailored conductivity, stability, and hydrophobicity to further boost the performance of Cu-based catalysts in CO₂ electrolysis.