Rapid microwave fabrication of new nanocomposites based on Tb-Fe-O nanostructures for electrochemical hydrogen storage application

Abstract

Nano-sized Tb-Fe-O (TFO) structures were fabricated via rapid microwave route using Tb(NO3)3⋅6H2O and Fe(NO3)3⋅9H2O precursors and verjuice (lemon juice) complexing agent as a surfactant. Verjuice complexing agent including collection of carboxylic acids control nucleation and growth of formed crystals with creation of spatial barrier around the cations, and finally prevent nano-product agglomeration. Changing of parameters in synthesis reaction consisting of surfactant, microwave power and solvent in turn offers a virtuous control over the nanocomposites size and shape which various compositions of pure TbFeO3 nanoparticles, Tb3Fe5O12/TbFeO3 and TbFeO3/Tb3Fe5O12 nanocomposites obtained. The as-prepared Tb-Fe-O nano-products were characterized thorough scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), UV–Vis, BET and energy dispersive X-ray (EDX) analyses in terms of crystallinity structure, composition, porosity and morphology. Different forms of Tb-Fe-O nanostructures were evaluated for electrochemical hydrogen storage capacity through chronopotentiometry technique in stable current (1 mA). The achieved Tb-Fe-O nanoparticles could be applied as a favorable candidate active material for electrochemical hydrogen storage. Optical, magnetic and reducible characteristics of Tb-Fe-O nanostructures have positive effect on electrochemical hydrogen storage capacity. It was found out that the TbFeO3/Tb3Fe5O12 nanocomposites have the best electrochemical hydrogen storage performance due to oxidation–reduction process of Fe2+/Fe3+ components which can help to charging-discharging process of hydrogen to increase the storage
capability to 490 mAh g-1 after 15 cycles.