Fluorine-induced porous carbon nanosheets with abundant edge-defects for high-performance capacitive deionization

Various large specific surface area carbon-based materials have been considered as fascinating electrode materials for capacitive deionization . However, the low adsorption capacity and sluggish desalination rates of traditional carbon-based materials still impede the further development of capacitive deionization. Herein, we successfully synthesized the nitrogen and fluorine co-doped porous carbon nanosheets (N, F@CNs) with abundant edge-defects via a facile one-pot strategy and systematically investigated its electrochemical properties for capacitive deionization. The introduction of F heteroatom not only effectively improves the edge-defect density and increases the adsorption sites, but also accelerates the ions and electrons transport, which can significantly enhance the electrochemical performance of the N, F@CNs. As a result, in an asymmetric CDI device, the N, F@CNs delivered an excellent salt (Na + ) adsorption capacity (71 mg g −1 ) at the applied potential of 1.2 V, which significantly higher than that of N-doped carbon nanosheets (32 mg g −1 ), along with outstanding cycling stability. Furthermore, the adsorption/desorption mechanisms involved were detailedly elucidated via systematic characterizations. Therefore, this work provides a new thought for designing carbon-based materials with excellent performance for capacitive deionization.