Improvement of supercapacitive and superparamagnetic capabilities of iron oxide through electrochemically grown La~(3+) doped Fe_3O_4 nanoparticles

摘要

In this paper, undoped and La~(3+) 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 voltam-metry (CV) and galvanostat charge-discharge (GCD) tests. The analyses results showed that both electrosynthesized samples have magnetite (Fe_3O_4) crystal structure. The doped IONPs exhibited composition of 15% wt La~(3+) cations incorporated into Fe_3O_4. 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 Fe_3O_4 is obtained as a result of La~(3+) 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 Ag-(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 La~(3+) iron oxide electrode.