Boosting Capacitive Deionization Performance via Bimetallic Synergistic Engineering of Electrospun Co/N-Doped Porous Carbon Nanofibers

Capacitive deionization (CDI) is an environmentally advantageous desalination technology that is particularly suitable for the treatment of low- to medium-concentration saline water. Among different electrode materials, carbon materials are widely used due to their good electrical conductivity and high specific surface area, while they suffer from limited ion adsorption capacity. In this study, a cobalt/nitrogen-doped porous carbon fiber composite with Zn-induced porosity (CoNG@V@CNF), where “V” stands for “volatile pore-forming agent”, has been successfully prepared via electrospinning combined with a high-temperature carbonization process. The introduction of trace Co nanoparticles enhances the stability of porous graphene. In addition, N doping contributes to improved wettability and electronic conductivity, and the carbon fiber structure constructs a three-dimensional conductive network, providing fast channels for ion transport. Electrochemical tests show that the specific capacitance of CoNG@V@CNF reaches 252.76 F g−1, demonstrating its superior charge storage capability. Furthermore, this study achieved a high salt adsorption capacity of 58.28 mg g−1 and a competitive desalination rate performance of 1.94 mg g−1 min−1. After 40 cycles of testing, the salt adsorption capacity (SAC) remains at 56.72 mg g−1, demonstrating its high stability during multiple charging and discharging processes. This work provides a new design strategy for developing high-performance CDI electrode materials.