Nitrogen-doped graphene composites as efficient electrodes with enhanced capacitive deionization performance

The desalination of seawater and brackish water is a desirable technique to address water scarcity today and in the uncertain future. Three-dimensional reduced graphene oxide-melamine formaldehyde composites (3D RGO-MF) were prepared by the carbonization of GO-MF composites, which were prepared through the electrostatic attraction between GO and MF nanoparticles. The obtained composites exhibited a hierarchical porous structure, with a specific surface area of 352 m(2) g(-1) and high degree of nitrogen doping of 10.86%. Thus, they had an enhanced specific capacity of 76.8 F g(-1), which is much larger than that of a pristine RGO electrode (23 F g(-1)). With their enhanced electrochemical capacity, the asprepared nitrogen-doped graphene composites were successfully employed as high performance electrodes for capacitive deionization. Their excellent electrochemical capacity with low inner resistance and high reversibility endows the 3D RGO-MF electrodes with an outstanding specific electrosorptive capacity of 21.93 mg g(-1) at a direct voltage of 2.0 V in NaCl aqueous solution. It was confirmed that the 3D RGO-MF electrode is quite appropriate for high-performance capacitive deionization.