Electrospun polyacrylonitrile/β-cyclodextrin based porous carbon nanofiber self-supporting electrode for capacitive deionization

Abstract

With β-cyclodextrin (β-CD) as an additive, porous carbon nanofibers (PCNF_β-CD) with good graphitization have been fabricated by electrospinning polyacrylonitrile/β-cyclodextrin (PAN/β-CD) pristine fibers followed by preoxidation and carbonization. The nanopores were formed by the dehydration and decomposition of β-CD at high temperature. The specific surface area and pore density can be conveniently tuned by adding different amounts of β-CD in the precursor solution. The resultant porous carbon fibers were characterized by scanning electron microscopy, N₂ adsorption/desorption analysis and fourier transform infrared spectroscopy. Raman analysis indicates that the graphitic network of the porous carbon is improved with the addition of β-CD. With the porous carbon fiber web as a self-standing electrode, the electrochemical properties of the electrodes were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. PCNF_β-CD were employed as active electrodes for capacitive deionization (CDI). The optimal desalination amount of 11.65 mg g⁻¹ was achieved on the PCNF_β-CD fabricated with the PAN/β-CD ratio of 1 : 0.8, which is significantly higher than that of pure PAN-based carbon nanofibers. Multiple charge–discharge cycling of the CDI cell was tested and the regeneration of the electrode was demonstrated.