Porous MnO_xCovered Electrospun Carbon Nanofiber for Capacitive Deionization

Using electrospun carbon nanofiber (ECNF) as substrate, the porous MnO X -encapsuled ECNF composites (A-ECNF/MnO x ) were fabricated via in-situ deposition of MnO 2 followed by heat-treatment. The MnO X loading amount was tuned by the deposition time in dilute KMnO 4 solution. The structure and surface properties of ECNF/MnO x composites before and after annealing treatment were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photo spectroscopy and contact angle test. The unique open porous surface structure of the fibers with mixed-valence Mn element has been realized by annealing treatment. The electrochemical properties of the annealed A-ECNF/MnO x composites have been greatly improved, with a specific capacitance as high as 200 F/g. With A-ECNF/MnO x composites as cathode in capacitive deionization (CDI) cell, the desalination amount of 8.2 mg/g and the charge efficiency of 70% were achieved, much higher than those of pristine ECNF and ECNF/MnOx without annealing, thanks to the ultrathin MnO x load, good hydrophilicity and the open porous surface of the composites. The A-ECNF/MnO x composite is a promising electrode material candidate for CDI application and for various electrochemical devices.