Unlocking efficient redox dechlorination through Fe/Fe3C nanoclusters embedded porous carbon nanofibers using capacitive deionization

Abstract

Development of novel and efficient dechlorination electrodes is essential for improving the capacitive deionization (CDI) performance. Herein, we proposed a hybrid anode material with Fe/Fe₃C nanoparticles encapsulated in porous carbon nanofibers (Fe/Fe₃C@CNFs) by a polyacrylonitrile (PAN)-based electrospinning strategy and subsequent pyrolysis. The PAN can provide additional carbon resource to induce the generation of Fe₃C nanoparticles with higher valence states and hold a confinement environment to prevent the agglomeration of nanoparticles, contributing to the stable and sufficiently exposed redox-active sites. Moreover, the PAN-derived porous carbon nanofibers built a conductive network with abundant cavities and pores to facilitate electron transport. As a result, the CDI dechlorination system of Fe/Fe₃C@CNFs delivered an outstanding Cl⁻ removal capacity of 126.4 mg g⁻¹ with a high retention rate of 91.0 % over 30 cycles. The Cl⁻ adsorption mechanism of Fe/Fe₃C@CNFs was proved to originate from the fast surface transformation reaction of the reversible Fe²⁺/Fe³⁺ redox couple, demonstrating its great potential as a superior pseudocapacitive electrode for CDI dechlorination. This study provides guidance on the construction of high-performance Cl-storage electrode for water remediation.