Zn-doped magnetite nanoparticles: development of novel preparation method and evaluation of magnetic and electrochemical capacitance performances

In this paper, metal ion (i.e. Zn²⁺) doped magnetite nanoparticles (Zn-MNPs) were prepared via a one-pot simple electrochemical platform. In this procedure, Zn-MNPs were electro-synthesized in a two-electrode system from an aqueous solution of mixed Fe(NO₃)₃/FeCl₂/ZnCl₂ (0.005 M). The applied electrochemical conditions included current density of 10 mA cm⁻², bath temperature of 25 °C and deposition time of 30 min. The structural and morphological characterizations through X-ray diffraction, field emission electron microscopy and energy-dispersive X-ray proved that the fabricated Zn-MNPs samples are composed of Zn²⁺ doped magnetite phase with particles with average size of 20 nm. Magnetic investigation by VSM revealed that the prepared Zn-MNPs have super-paramagnetic behavior, where they exhibited saturation magnetization (Ms), remanent magnetization (Mr) and coercivity values of 54.47 emu g⁻¹, Mr = 0.41 emu g⁻¹ and H _Ci = 10.53 G, respectively. The charge storage ability of the prepared Zn²⁺ doped MNPs was evaluated as electrode material for supercapacitors through cyclic voltammetry (CV) and galvanostat charge–discharge (GCD) techniques. The obtained electrochemical data showed that these materials are capable to deliver specific capacitance as high as 164.3 F g⁻¹ at current load of 1 A g⁻¹, and 89.4% capacity retention after 1000 GCD cycling. The results proved the suitability of the electro-synthesized nanoparticles for use in supercapacitors. Based on the obtained results, our developed electro-synthesis method was propped as a facile procedure for the synthesis of high performance Zn²⁺ doped magnetite nanoparticles.