Improved supercapacitive performance of pure iron oxide electrode through cathodically grown of ultra-fine nanoparticles

[Display omitted] •Ulrta-fine Fe3O4 nanoparticles with size of 5nm were prepared.•PEG plays important role in the formation of fine nanoparticles.•Specific capacitance of iron oxide electrode was improved. In this letter, Fe3O4 ultra-fine nanoparticles are prepared through PEG-assisted cathodic electrosynthesis from ethanol media. The XRD, FE-SEM, TEM and BET data confirmed the pure phase (i.e. magnetite), fine particle size (∼5nm) and high surface (176.7m2/g) of the electro-synthesized product. The electrochemical evaluations through cyclic voltammetry (CV) and continuous charge-discharge (GCD) techniques proved that the prepared Fe3O4 nanoparticles have excellent capacitive storage as high as 218.3Fg−1 and stable cycling performance of 4.7% decay after 2000 cycling at 0.5Ag−1. Furthermore, this work provides a facile electrochemical procedure to fabricate high performance iron oxide electrode for use in supercapacitors.