Cyclodextrin/Graphene-Based Porous Carbon Nanofibers with Embedded MnO2 Nanoparticles for Supercapacitor Applications

Three kinds of free-standing cyclodextrin (CD)/graphene-based porous carbon nanofiber (CNF) composites with MnO(2 )prepared using alpha-, beta-, and gamma-CD are investigated for their morphological and electrochemical properties to compare their electrochemical applicability in aqueous electrolytes. The stability of the optimized structure of gamma-CD/graphene-based porous CNF with MnO2 (PMnG(gamma)) is confirmed by density functional theory calculations. Results show that when graphene is added, MnCl2 forms an inclusion complex with gamma-CD well, and then MnO2 particles are embedded in the CNF matrix under the influence of these inclusion complexes after heat treatment. The PMnG(gamma) composites, in which the electrochemically active material of MnO2 particles is embedded in the fiber, maximize the synergistic effect of the pseudocapacity of MnO2 and the electric double-layer capacity induced by the highly porous surface. Hence, the PMnG(gamma) electrodes exhibit high specific capacitance (235 Fg(-1) at a constant current density of 1 mA cm(-2)), energy density (25.5-12.2 Wh kg(-1) at power densities ranging from 400 to 10,000 W kg(-1)), and high long-term stability of more than 96% after 10,000 cycles in aqueous solution.