In situ immobilized, magnetite nanoplatelets over holey graphene nanoribbons for high performance solid state supercapacitor

Among major phases of iron oxide, magnetite (Fe3O4) is potential candidate for pseudocapacitors. Yet, the clustering of magnetite nanoparticles confines them from being exploited as charge storage material. Herein, magnetite hexagonal nanoplatelets are synthesized on holey graphene nanoribbons (GNRs) by hydrothermal route and tested for charge storage performance in solid-state supercapacitor incorporating gel electrolyte (PVA-H2SO4). GNR besides providing large surface for adsorption of magnetite platelets also improved the charge collection ability of nanocOmposite through interconnected nanoribbon network. Mass loading over GNR is optimized to a maximum of 30 wt. (%) by ensuring mono dispersion of magnetite nanoplatelets and high conductivity (14.0 S m(-1)) of nanocomposite. Above 50 wt. (%) magnetite loading, structural identity of nanofibbon is tempered and as a consequence increased network resistivity depletion in charge storage capacity is observed. Mass loading of magnetite over nanoribbon showed an inverse relationship with ion diffusion and electronic conduction. Balanced ionic and electronic conduction in 30 wt. (%) magnetite loaded nanoribbon results in a supercapacitor cell delivering 1241.5 W kg(-1) while maintaining 26.9 Wh kg(-1) energy density. About 95% capacitance retention over 3000 charge discharge cycles at 2.3 A g(-1) demonstrate magnetite as a high performance supercapacitor electrode. (C) 2016 Elsevier Ltd. All rights reserved.