Nitrogen-doped hierarchical porous carbon aerogel for high-performance capacitive deionization

Abstract Capacitive deionization (CDI) has emerged as a promising energy-efficient, low cost technique for water treatment and desalination. Herein, we report a nitrogen-doped hierarchical porous carbon aerogel (N-HPCA) for high-performance CDI. The obtained N-HPCA possess a highly interconnected hierarchical porous structure, providing a large specific surface area of 2405 m 2  g −1 and abundant mesopores ranging from 2 to 5 nm for the adsorption and efficient transport of ions. Meanwhile, N-doping largely enhances the conductivity and surface wettability of the carbon material. Consequently, the N-HPCA delivers a high specific capacitance (263 F g −1 in 6 M KOH solution and 153 F g −1 in 0.5 M NaCl solution), enabling an outstanding electrosorption capacity of 17.9 mg g −1 in 500 mg L −1 NaCl solution. Moreover, the N-HPCA electrode also demonstrates good cycle stability, without obvious attenuation in electrosorption capacity upon 5 CDI cycles. These results demonstrate that the rationally designed N-HPCA shows great potential for practical CDI application.