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

The large-scale production of carbon monoxide (CO) through electrochemical CO reduction reaction (CORR) represents a promising strategy for mitigating CO emissions and energy crisis. However, the development of high-efficiency, stable, and pH-universal electrocatalysts for CORR 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 CORR-to-CO. The CoNi@N-CNTs demonstrate a high CO Faradaic efficiency (FE) above 90% in acidic, neutral, and alkaline electrolytes, and the partial current densities of CO can reach 732, 354, and 348 mA cm, respectively. The porous structure enhances electrolyte accessibility and CO 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.