Rod-like nitrogen-doped carbon hollow shells for enhanced capacitive deionization

A rod-like hollow graphitic carbon shell with nitrogen doping was fabricated via a template-assisted growth for enhanced capacitive deionization. The silica nanorods prepared as the templates have uniform structures, which can effectively avoid aggregation. Nitrogen-doped graphitic carbon is favourable for higher electrical conductivity. The hollow structure obtained after etching provides a large ion-accessible surface area. The resultant rod-like nitrogen-doped carbon hollow shells have a hierarchically porous architecture with high electrical conductivity and a beneficial porosity. In this work, the morphology, structure, specific surface area, and porosity were carefully investigated using SEM, TEM, XRD, Raman, BET and BJH methods. Electrochemical test and electrosorptive test were conducted to analyse the specific capacitance, electrosorption capacitance and cycle ability. The largest electrosorption capacity was achieved as 16.72 mg g⁻¹ at 1.6 V in 250 mg g⁻¹ solution. Moreover, the adsorption kinetics were investigated using Lagergeren's model. Overall, the nitrogen-doped carbon hollow shell is demonstrated as a promising candidate of electrode material for water desalination via capacitive deionization.