Synthesis and Capacitive Properties of Manganese Oxide Nanoparticles Dispersed on Hierarchical Porous Carbons

A growing manganese dioxide (MnO2) nanoparticles on hierarchical porous carbons (HPCs) is conducted via a simple route starting with KMnO4 and ethanol aimed to enhance the electrochemically active surface area of MnO2. It is found that these MnO2 nanoparticles are uniformly grown on the external surface of the HPCs and still maintain hierarchical porous structure, yielding a composite electrode showing good electron transport, rapid ion penetration, fast and reversible Faradic reaction when used as supercapacitor electrode materials. HPCs-MnO2 composite displays the specific capacitance as high as 167 Fg(-1) and 192 F cm(-3) in 3 M KOH aqueous electrolyte and 94 F g(-1) and 113 F cm(-3) in 1 M tetraethylammonium tetrafluoroborate/propylene carbonate (Et4NBF4/PC) organic electrolyte. Furthermore, it also exhibits a superior cycling stability with 96% retention of the initial specific capacitance after 1000 cycles and stable Coulombic efficiency of 99% in 3 M KOH measured using the galvanostatic charge-discharge technique. (C) 2015 Elsevier Ltd. All rights reserved.