Hierarchically open-porous nitrogen-incorporated carbon polyhedrons derived from metal-organic frameworks for improved CDI performance

Capacitive deionization (CDI) is considered as a simple, robust, and environmentally favorable technology for water treatment. High performance electrode materials beyond commercial activated carbons (AC) should be developed for the practical application of CDI. Herein, we demonstrate hierarchically open-porous nitrogen-incorporated activated nanoporous carbon polyhedron (A-NCP) derived from metal-organic frameworks (MOFs) for high performance CDI electrodes. Owing to the 3D morphology with open nanoporous surface, macroporous channels by interlinked polyhedron particles, and electric conductivity by doped nitrogen, A-NCP delivers a high desalination capacity of 24.4 mg/g with a low concentration of 100 mg/mL at 1.2 V, revealing faster kinetic performance than that of commercial AC in the batch-mode CDI. Varying operating conditions such as applied voltage, concentration, and feed rate of saline water in a single-pass experiment, high salt adsorption capacity and fast ion removal of A-NCP are obtained, achieving high position of CDI Ragone plot.