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. The N, F@CNs exhibits an outstanding salt adsorption capacity, along with outstanding long-term cycling performance. • The nitrogen and fluorine co-doped porous carbon nanosheets (N, F@CNs) with abundant edge-defects was prepared via a facile one-pot strategy. • The introduction of F heteroatom effectively improved the edge-defect density and increased the adsorption sites. • The N, F@CNs exhibited an outstanding salt (Na + ) adsorption capacity. • The desalination mechanisms involved was elucidated by comprehensive characterizations.