One-Pot Flash Combustion Synthesis, Structural, Morphological and Opto-Magnetic Properties of Spinel Mn x Co1−x Al2O4 (x = 0, 0.3, and 0.5) Nanocatalysts

Abstract

Spinel Mn x Co1−xAl2O4 (x = 0, 0.3, and 0.5) nanoparticles were synthesized by a simple microwave-assisted combustion method. Powder X-ray diffraction (XRD) analysis was confirmed the formation of single phase, cubic spinel structure without other impurities. Average crystallite sizes of the samples were found to be in the range of 10.12 nm to 1623 nm by Scherrer’s method. FT-IR spectra showed the stretching frequencies corresponding to the M–Al–O bond of spinel structure. High-resolution scanning electron microscope (HR-SEM) and high-resolution transmission electron microscope (HR-TEM) images showed the particle-like nanostructures. Band gap energy was estimated using UV-Visible DRS spectra and the values are increased with increasing Mn2+ content (345 eV to 3.75 eV). Vibrating sample magnetometer (VSM) measurements revealed that pure and Mn-doped CoAl2O4 samples have ferromagnetic behavior and the magnetization values increased with increasing the concentration of Mn2+ ions in the CoAl2O4lattice. Catalytic oxidation of benzyl alcohol into benzaldehyde was found that the sample Mn0.5Co0.5Al2O4showed 96.58 % conversion with 100 % selectivity, whereas pure CoAl2O4, the conversion was only 87.43 % with 100 % selectivity.