Improvement of supercapacitive and superparamagnetic capabilities of iron oxide through electrochemically grown La3+ doped Fe3O4 nanoparticles

In this paper, undoped and La3+ doped iron oxide nanoparticles (IONPs and La-IONPs) are prepared through a one-step electrosynthesis process. The prepared La-IONPs are characterized by X-ray diffraction (XRD), field emission electron microscopy (FE-SEM), energy-dispersive X-ray (EDX) and vibrating sample magnetometer (VSM) analyses. Furthermore, the electrochemical performance of IONPs and La-IONPs are evaluated using cyclic voltammetry (CV) and galvanostat charge-discharge (GCD) tests. The analyses results showed that both electrosynthesized samples have magnetite (Fe3O4) crystal structure. The doped IONPs exhibited composition of 15% wt La3+ cations incorporated into Fe3O4. Also, both IONPs and La-IONPs samples have nano-particle morphologies with particle size of 15 and 20 nm, respectively. The VSM data indicated that an improvement in the superparamagnetic behavior of Fe3O4 is obtained as a result of La3+ doping, where La-IONPs sample exhibited smaller remanent magnetization (Mr) and coercivity (Ci) values as compared with undoped IONPs. Furthermore, GCD showed that La-IONPs are capable to deliver specific capacity value of 187 F g(-1) and 84.8% after 2000 discharging cycles at 1 A g(-1), where undoped IONPs electrode exhibited specific capacity and cycle life of 145 F g(-1) and 78.7%, respectively, at the same discharging conditions. The obtained results well established the improvement of capacitive characters for La3+ iron oxide electrode.