CoNi Alloy Nanoparticles Encapsulated Within N-Doped Carbon Nanotubes for Efficiently pH-Universal CO₂...

The large-scale production of carbon monoxide (CO) through electrochemical CO₂ reduction reaction (CO₂RR) represents a promising strategy for mitigating CO₂ emissions and energy crisis. However, the development of high-efficiency, stable, and pH-universal electrocatalysts for CO₂RR is of utmost urgency. In this study, CoNi alloy nanoparticles encapsulated within N-doped carbon nanotubes (N-CNTs) are synthesized and employed as robust catalysts toward CO₂RR-to-CO. The CoNi@N-CNTs demonstrate a high CO Faradaic efficiency (FE_CO) above 90% in acidic, neutral, and alkaline electrolytes, and the partial current densities of CO can reach 732, 354, and 348 mA cm^-2, respectively. The porous structure enhances electrolyte accessibility and CO₂ diffusion, and the strong interaction and the unique armor structure between N-CNTs and CoNi alloy protect the internal active sites, which attributes to improving the catalytic activity and stability in pH-universal systems. Density functional theory (DFT) results indicate that electron transfer significantly influenced the charge redistribution of Co and Ni, reducing the energy barrier for ^*COOH formation and weakening ^*CO adsorption, ultimately improving electrocatalytic performance for CO generation.