Capacitive deionization (CDI) with high energy efficiency, low cost, and non-secondary pollution is considered an emerging desalination technology. To pursue excellent electrode materials with high electrosorption capacity is highly desired… Click to show full abstract
Capacitive deionization (CDI) with high energy efficiency, low cost, and non-secondary pollution is considered an emerging desalination technology. To pursue excellent electrode materials with high electrosorption capacity is highly desired for practical CDI application. In this work, the protic salt-derived porous carbon was synthesized via the direct pyrolysis of the protic salt, i.e., p-phenylenediamine bisulfate ([pPDA][2HSO4]), which was obtained by simply neutralizing p-phenylenediamine with sulfuric acid. The resultant carbon materials possessed large specific surface area, high nitrogen doping, good graphitization and large mesopores. These intrinsic characteristics endowed protic salt-derived porous carbon with excellent electrochemical properties and CDI desalination performance. Particularly, the carbon obtained at 900 °C (C-9) with optimal porous structure (1082 m2 g−1) and chemical composition (5.2% N) exhibited the best electrochemical property with a specific capacitance of 222.3 F g−1. The CDI results showed that C-9 had a high electrosorption capacity of 16.5 mg g−1 in 100 mg L−1 NaCl solution and excellent electrosorption stability over 20 times of adsorption-desorption cycles. Furthermore, we demonstrated the dependence of CDI performance on the balance between porous structure and chemical composition. These results imply that the protic salt-derived porous carbon should be a promising electrode material for CDI application.
               
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