Fabrication of Anion-Exchange Polymer Layered Graphene–Melamine Electrodes for Membrane Capacitive Deionization

A novel nitrogen-doped reduced graphene sponge composite (NRGS) is fabricated by using melamine sponge to restrain the aggregation of graphene sheets during reduction. The anion-exchange polymer layered graphene composites (A-NRGS) are prepared by coating the surface of the NRGS electrode with cross-linked poly(vinyl alcohol) with quaternization modification (C-qPVA). With the help of a melamine sponge to suppress the agglomerate of graphene sheets, the NRGS exhibits a unique three-dimensional (3D) interconnected porous structure with abundant nitrogen doping of 5.2%. Its specific surface area is up to 241 m2/g. In addition, the enhanced wettability of A-NRGS composites favors the diffusion of ion from the electrolyte to electrode. Therefore, A-NRGS composites have excellent electrochemical capacity (184 F/g). The membrane capacitive deionization (MCDI) performance for A-NRGS electrode (11.3 mg/g) is higher than that of pristine reduced graphene oxide (RGO) (6.2 mg/g) and NRGS (8.6 mg/g) electrodes. All t...