Enhanced chloride removal of phosphorus doping in carbon material for capacitive deionization: Experimental measurement and theoretical calculation

Abstract Heteroatoms doping is an important modification method in carbon electrode for CDI technology. In this study, a new facile approach of homogeneous phosphorus doping in carbon matrix was proposed via crosslinking polymerization of m-phenylenediamine and phytic acid. The carbonized composites (NPC) showed the characteristics of phosphorus/nitrogen co-doping with excellent hydrophilicity, high electrochemical performance, lower inner resistance and good cycling stability, far beyond that of carbon without phosphorus doping. Compared with reported similar materials and commercial carbon, the chloride adsorption capacity of NPC used as electrode for deionization capacitors was significantly improved (21.4 mg g−1 in a 500 mg L−1 Cl− solution at 1.2 V). Particularly, based on the charge distribution analysis of phosphorus doping in carbon matrix by using Material Studio calculation, the possible enhanced dichlorination mechanism of the carbon composites as electrode for deionization capacitors was carefully explored. The phosphorus/nitrogen co-doped carbon displayed a promising prospect for chloride removal in the application of CDI technology.