Nanoarchitectonics of heteroatom-doped hierarchical porous carbon derived from carboxymethyl cellulose carbon aerogel and metal-organic framework for capacitive deionization

Capacitive deionization (CDI) using porous materials offers a sustainable solution for providing affordable freshwater, but the low salt adsorption rate of benchmark carbon materials significantly limit the practical implementation. Herein, we utilized carboxymethyl cellulose sodium (CMC) as the carbon skeleton to produce a composite carbon aerogel loaded with ZIF-8 (ZIF-8/CMC-CA). The presence of ZIF-8 nanoparticles improved the pore structure of the material and provides a certain pseudo capacitance by introducing N. Compared with ZIF-8 derived carbons (ZIF-8-C), the CMC provided a good three-dimensional structure for the dispersion of ZIF-8 nanoparticles, reduced the agglomeration of particles. Furthermore, numerous carboxyl and hydroxyl groups on CMC enhanced the hydrophilicity of materials. Due to the interconnected structure, ZIF-8/CMC-CA exhibited excellent conductivity, a high specific surface area, and offered suitable channels for the rapid entry and exit of ions. In a three-electrode system, the total specific capacitance of the ZIF-8/CMC-CA electrode was 357.14 F g-1. The adsorption rate of ZIF-8/CMC-CA was 2.02 mg g-1 min-1 in a 500 mg L-1 NaCl solution. This study may provide new insight for modifying and fabricating electrode materials for practical CDI applications.