ZnFe2O4-infused hierarchically porous carbon nanofiber electrode for enhanced capacitive deionization

Highly porous carbon materials with abundant active adsorption sites are desirable for capacitive deionization (CDI). However, their limited salt adsorption capacity, slow desalination rate, and sensitivity to salt concentrations hinder practical applications in low salinity water treatment. In this study, we successfully synthesized a hierarchically porous carbon nanofiber electrode infused with ZnFe2O4 prepared by electrospinning the FeⅢ-MOF-5/benzoxazine/polyacrylonitrile (FeⅢ-MOF-5/BA-a/PAN) system, followed by high-temperature curing, KOH activation, and carbonization processes. The activated electrode material exhibited remarkable characteristics, including an exceptionally high specific surface area of 2506.73 m2 g−1 and significantly enhanced mesoporosity. Results demonstrated pseudo-capacitive behavior with a specific capacitance of 149.3 F g−1 and excellent electrochemical cycling stability. Notably, the electrode showed significant adsorption capacities in a 1000 mg L−1 NaCl solution at applied potentials of 1.2 and 1.6 V, with values of 74.27 and 88.95 mg g−1, respectively. The adsorption process followed both the Freundlich isotherm and the pseudo-second-order kinetic models. These findings highlight the promising potential of the ZnFe2O4-infused porous carbon nanofiber electrode for efficient desalination and ion removal applications.