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.