Nitrogen and fluorine co-doped 3-dimensional reduced graphene oxide architectures as high-performance electrode material for capacitive deionization of copper ions

[Display omitted] •Nitrogen and fluorine doped 3-D reduced graphene oxide (rGO) through hydrothermal route was prepared.•High capacitive deionization of Cu2+ ions by 3D-NFrGO when applied in capacitive electrode material.•Chemisorption and ion diffusion onto electrode govern the Cu2+ ion removal.•Heteroatoms doping, good surface area and pore structure result in high specific capacitance. Heavy metal ions pose a threat to human life as their consumption can be hazardous. In this regard, unprecedented interests towards the development of technology for water purification have been witnessed. The present work is yet another novel attempt to develop a promising nanomaterial for the removal of Cu(II) from aqueous media using fast and facile capacitive deionization (CDI) method. Nitrogen- and fluorine- co-doped 3-dimensional reduced graphene oxide (3D NFrGO) architectures were developed via a hydrothermal route at 180 °C for 12 – 24 h and then applied as CDI electrode for Cu(II) removal. The fabrication of NFrGO at 180 °C for 16 h shows excellent 3D structures with high specific surface area of 182.7 m2 g−1 and bimodal pore size distribution at 2.1 and 5.6 nm, which can facilitate rapid ions/electrons transport inside the interconnected mesoporous channels. In addition, the doping of heteroatoms can not only increase the conductivity, but also create the vacancy defect of NFrGO, resulting in accelerated electrochemical performance. The specific capacitance of 245.6 F g−1 was also achieved, demonstrating the high capacitive features of the as-obtained material. Moreover, a high percent removal of 95% and specific electrosorption capacity of 52.4 mg g−1 at 100 mg L-1 Cu(II) was obtained. Electrosorption results can be well-described by the pseudo second-order adsorption kinetics and the intraparticle diffusion model, which signify that chemisorption and ion diffusion into electrode pores govern Cu(II) removal. Results obtained in this study have demonstrated that N, F-co-doped 3D rGO can be a promising CDI material for efficient removal of heavy metal ions as well as for water purification.