Cu nanoparticles embedded in fluorinated mesoporous carbon for enhanced CO₂ electroreduction to C₂ products

The utilization of renewable electricity to drive the electrochemical CO₂ reduction reaction (CO₂RR) presents an attractive avenue for achieving carbon neutrality, as it facilitates the conversion of CO₂ into valuable chemicals and fuels. However, producing high-energy-density multi-carbon hydrocarbon products (C₂₊) still suffers from low selectivity, and the process proves highly sensitive to both catalyst structure and electrolyte conditions. Here, we report the synthesis of fluorinated mesoporous carbon-confined copper nanoparticles (Cu@F-MC) via a bottom-up molecular self-assembly and carbonization strategy. The Cu@F-MC catalyst established a two-dimensional (2D) mesoporous structure with well-dispersed 6.5 nm-wide mesopores and a high surface area. The confinement effect of mesoporous carbon enabled the small size and well dispersion of Cu nanoparticles (~ 10 nm). The fluorine-doped structure not only effectively inhibited the side hydrogen evolution reaction, but also modulated the local electronic structures of Cu nanoparticles toward multi-carbon product generation. Thus, the Cu@F-MC exhibited a high current density of 500 mA·cm⁻² with an ethanol Faradaic efficiency (FE) of 40% for CO₂ reduction in a flow cell, and a prolonged stability with over 50% selectivity for ${\mathrm{F}\mathrm{E}}_{{\mathrm{C}}_{2+}}$ during a 70h continuous electrolysis in the membrane electrode assembly test. This strategy offers a promising approach to concurrently improve the selectivity and stability of copper-based catalysts in CO₂RR.