Comparative Studies of Spinel MnFe2O4 Nanostructures: Structural, Morphological, Optical, Magnetic and Catalytic Properties

Spinel MnFe2O4 nanostructures with two different morphologies such as nanoflakes (NFs) and nanoparticles (NPs) were synthesized by a simple microwave-assisted combustion (MACM) and conventional combustion (CCM) methods respectively. Powder X-ray diffraction (XRD) study showed that the samples have pure cubic spinel phase and the average crystallite size is found to be 15.13 +/- 2 nm and 24.38 +/- 13 nm for NFs and NPs respectively. The calculated lattice parameter values of the samples NFs and NPs are 8.476 and 8.474 angstrom respectively. The morphology of the samples was recorded using high resolution scanning electron microscope (HR-SEM) analysis and was found that nanoflakes and nanoparticles morphologies by MACM and CCM methods respectively. Energy dispersive X-ray (EDX) results showed that the composition of the elements was relevant as expected from these combustion methods. The optical properties of the as-prepared nanostructures were also investigated by UV-Visible Diffuse Reflectance Spectroscopy (DRS) and Photoluminescence (PL) Spectroscopy. The energy band gap (E-g) of the sample NFs is 1.78 eV, whereas the sample NPs has 1.75 eV. The magnetic properties were investigated using the Vibrating Sample Magnetometer (VSM) at room temperature and the hysteresis loops confirmed the super-paramagnetic behavior for both samples with saturation magnetization (M-s) values in the range of 59.29 +/- 11 and 66.78 +/- 06 emu/g for the samples NFs and NPs respectively. The oxidation of benzyl alcohol into benzaldehyde reached a maximum of 87.65% for MnFe2O4 NFs, whereas for MnFe2O4 NPs, the conversion was only 69.43% with 100% selectivity.