A Simple Combustion Synthesis and Optical Studies of Magnetic Zn1-xNixFe2O4 Nanostructures for Photoelectrochemical Applications

Ni-doped ZnFe2O4 (NixZn1-xFe2O4; x = 0.0 to 0.5) nanoparticles were synthesized by simple microwave combustion method. The X-ray diffraction (XRD) confirms that all compositions crystallize with cubic spinel ZnFe2O4. The lattice parameter decreases with increase in Ni content resulting in the reduction of lattice strain. High resolution scanning electron microscope (HR-SEM) and transmission electron microscope (HR-TEM) images revealed that the as-prepared samples are crystalline with particle size distribution in 42-50 nnn range. Optical properties were determined by UV-Visible diffuse reflectance (DRS) and photoluminescence (PL) spectroscopy respectively. The saturation magnetization (M-s) shows the superparamagnetic nature of the sample for x = 0.0-0.2, whereas for x = 0.3-0.5, it shows ferromagnetic nature. The M-s value is 1.638 emu/g for pure ZnFe2O4 sample and it increases with increase in Ni content. Photoelectrochemical (PEC) measurements showed a significant increase of photocurrent density with increase in the Ni-dopant, and 0.5% Ni-doped ZnFe2O4 sample was found to show the better photoresponse than the other doping concentrations.