Boosting Electrochemical CO₂ Reduction to CO by Regulating the Porous Structure of Carbon Membrane

Ni single-atom-decorated nitrogen-doped carbon materials (Ni-N-C) have demonstrated high efficiency in the electrochemical reduction of CO₂ (CO₂RR) to CO. In this study, Ni-N-C active sites were embedded within a carbon membrane via an electrospinning and pyrolysis process. The resulting self-supported carbon membrane hosting Ni-N-C sites could be directly utilized as an electrode for the CO₂RR. To enhance the CO₂RR performance of the carbon membrane, the porous structure of the carbon membrane was fine-tuned by incorporating a pore-forming agent. The optimized porous carbon membrane electrode, K_0.66-Ni-NC, achieved an impressive CO faradaic efficiency (FE_CO) of over 90% within a wide potential range from -0.8 to -1.6 V vs RHE for CO₂RR. Additionally, it maintained an FE_CO of above 90% at -0.8 V vs RHE throughout a 30 h durability test in an H-cell. Further analysis has revealed that the porous structure of the carbon membrane not only facilitates the mass transport of CO₂ but also increases the level of exposure of active sites during the CO₂RR.