Flexible 8-MnO2 nanosheet-infixed porous carbon nanofibers for capacitive deionization

Birnessite-type manganese dioxide (8-MnO2) is a typical pseudocapacitive material with the merits of natural abundance, environmental friendliness and high specific capacitance. Herein, the ultrathin 8-MnO2 nanosheets were successfully infixed on the electrospun porous carbon nanofibers (PCNF) by self-limitation reaction. The KMnO4 concentration and the hierarchical pore structure greatly affected the growth of 8-MnO2 nanosheets on the PCNF. Under the optimal condition, the as-prepared flexible 8-MnO2@PCNFs electrode delivered extremely high specific capacitance of 455.3 F g-1. As a cathode in capacitive deionization (CDI), 8-MnO2@PCNF presented the salt adsorption capacity of 15.9 mg g-1, with ultrafast adsorption speed (1.8 mg g-1 min-1). The 8-MnO2@PCNF materials has excellent recycling stability in CDI device due to the interconnected structure of 8-MnO2 nanosheets inserted in PCNF.