N-doped hierarchical porous carbon derived from hypercrosslinked diblock copolymer for capacitive deionization

Capacitive deionization (CDI) has attracted huge interest as an emerging desalination technology. To explore carbon electrode materials with high performance is the key for CDI technology. In this work, the N-doped hierarchical porous carbon (N-HPC) was fabricated via pyrolysis of hypercrosslinked diblock copolymer (PEO₁₁₃-b-PS₁₉₂) with a nitrogen-enriched melamine. The as-prepared N-HPC was further applied as CDI electrode. This electrode showed enhanced electrochemical performance with a specific capacitance of 182.6 F g^-1 and an outstanding electrosorption capacity of 13.76 mg g^-1 in 500 mg L^-1 NaCl solution, which are higher than those of its undoped counterpart (66.7 F g^-1 and 10.27 mg g^-1, respectively). Such an improvement was attributed to synergistic effect from the combination of nitrogen-doped property and the hierarchical porous structure. After 6 adsorption-desorption cycles, a stable electrosorption capacity can be realized without appreciable declination, suggesting a good repeatability of electrosorption process. These results imply that N-HPC has great potential as a promising electrode material for CDI application.