The synthesis and super capacitive characterization of microwave-assisted highly crystalline α-Fe 2 O 3 /Fe 3 O 4 nanoheterostructures.

A facile microwave-assisted solvothermal process for the synthesis of narrow-size distributed α-Fe 2 O 3 , α-Fe 2 O 3 /Fe 3 O 4 , and Fe 3 O 4 nanostructures was demonstrated using PVP as a surfactant. During the reaction, the influence of the reaction media, such as the mixture of ethylene glycol and water on the formation of α-Fe 2 O 3 , α-Fe 2 O 3 /Fe 3 O 4 , and Fe 3 O 4 was systematically studied. Interestingly, pure aqueous medicated solvothermal reaction conferred phase pure rhombohedral Fe 2 O 3 (hematite) and linearly upsurging the formation of cubic Fe 3 O 4 (magnetite) with the increasing concentration of EG and further, in pure EG, it deliberated cubic Fe 3 O 4 . FESEM and FETEM images of α-Fe 2 O 3 /Fe 3 O 4 nano heterostructure clearly showed the nanosized Fe 3 O 4 particles of 4-6 nm decorated onto Fe 2 O 3 nanoparticles. Further, the electrochemical properties of α-Fe 2 O 3 , α-Fe 2 O 3 /Fe 3 O 4 , and Fe 3 O 4 nanoparticles were investigated with galvanostatic charge-discharge and cyclic voltammetry measurements using a 3-electrode system. The findings show that their specific capacitances are linked to the type of iron oxide. More significantly, the α-Fe 2 O 3 /Fe 3 O 4 nanoheterostructure exhibited the utmost capacitance of 165 F g -1 , which is greater than that of pristine α-Fe 2 O 3 and Fe 3 O 4 . Enhancement in the electrochemical performance was found due to the improved charge transfer that occurred at the interface of the nanoheterostructure. The nanoparticles of Fe 3 O 4 deposited on the Fe 2 O 3 increased the active sites, which accelerated the process of adsorption and desorption of ions, thereby enhancing the interface-assisted charge transfer and reducing the internal resistance, which is ultimately responsible for enhanced capacitance. Such heterostructures of nano iron oxide may fulfill the requirements of electrodes in supercapacitors.