Evaluation of supercapacitive and magnetic properties of Fe3O4 nano-particles electrochemically doped with dysprosium cations: Development of a novel iron-based electrode

In this research, a novel one-pot fabrication platform was developed for the preparation of Dy3+-doped iron oxide nanoparticles (Dy-IONPs). In the procedure, Dy-IONPs are electro-deposited from an additive-free aqueous mixed solution of iron(III) nitrate, iron(II) chloride and dysprosium chloride salts through applying a current density of 10 mA cm-2 for 30 min. The analytical data obtained from X-ray diffraction (XRD), field emission electron microscopy (FE-SEM) and energy-dispersive X-ray (EDX) confirmed the deposited Dy-IONPs to be composed of magnetite nanoparticles (size≈20 nm) containing about 10 wt% of Dy3+ cations as the doping agent. The electrochemical data obtained through galvanostatic charge-discharge (GCD) tests showed that Dy-IONPs provide specific capacitances values of as high as 202 and 111 F g−1at the discharge loads of 0.5 and 5 A g−1, respectively, and reveal capacity retentions of 93.9% and 77.2% after 2000 GCD cycling. These could be held as proof that the electro-synthesized Dy3+-doped Fe3O4 NPs are suitable candidates for use in supercapacitors. Furthermore, the results of vibrating sample magnetometer (VSM) measurements indicated better superparamagnetic behavior of the Dy-IONPs (Mr = 0.34 emu g-1 and HCi= 6.25 G) as opposed to pure IONPs (Mr = 0.95 emu g-1 and HCi= 14.62 G), which originates from their lower Mr and Hci values. Based on the results, the proposed electro-synthesis method offers a facile procedure for the preparation of high- performance metal-ion-doped IONPs.