Efficient capacitive deionization with 2D/3D heterostructured carbon electrode derived from chitosan and g-C3N4 nanosheets

Abstract

Exploring green and low-cost electrode materials with outstanding desalination performance is essential for the practical application of capacitive deionization (CDI). Herein, we introduced 2D g-C3N4 nanosheets into the bio-based 3D chitosan-derived porous carbon (CCS) to form the 2D/3D nitrogen-doped heterostructured porous carbon (CCS/GCNS) via a hydrothermal-activation strategy. Owing to the synergistic interaction of 3D CCS and 2D g-C3N4 nanosheets, CCS/GCNS exhibited large specific surface area (2529.3 m2 g-1), hierarchical porous structure, enriched nitrogen content (9.8 at.%), and excellent wettability. Benefiting from the efficient charge diffusion channels of the 3D CCS skeleton and the enhanced dispersion of 2D g-C3N4 nanosheets, CCS/GCNS displayed extraordinary specific capacitance (312.8 F g-1). Additionally, the unique heterostructured CCS/GCNS electrode presented a remarkable desalination capability of 32.8 mg g-1, rapid adsorption-desorption reaction, and stable recycling behavior in CDI tests. These findings provide new insights into highly efficient, highly stable metal-free and green electrodes based on 3D/2D hybrid materials for CDI applications.