A Novel Synthesis, Structural, Morphological, and Opto-magnetic Characterizations of Magnetically Separable Spinel CoxMn1−xFe2O4 (0 ≤ x ≤ 1) Nano-catalysts

• Published in: Journal of superconductivity and novel magnetism 2014-12, Vol.27 (12), p.2841-2857
• Main Authors: Manikandan, A., Durka, M., Antony, S. Arul
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Condensed Matter Physics; Magnetic Materials; Magnetism; Original Paper; Physics; Physics and Astronomy; Strongly Correlated Systems; Superconductivity
• ISSN: 1557-1939; 1557-1947
• DOI: 10.1007/s10948-014-2771-1

Spinel Co x Mn 1− x Fe 2 O 4 (0≤ x ≤1) nano- crystals were successfully synthesized by a simple microwave-assisted combustion method. High-resolution scanning electron microscopy (HR-SEM) and transmission electron microscopy (HR-TEM) analysis was used to study the morphological variations and found the particle-like nanocrystal morphologies. Energy dispersive X-ray (EDX) results showed that the composition of the elements were relevant as expected from the combustion synthesis. Powder X-ray diffraction (XRD) analysis showed that all composition was found to have cubic spinel-type structure. Average crystallite size of the samples was found to be in the range of 10.36–21.16 nm. The lattice parameter decreased from 8.478 to 8.432 Å with increasing Co 2+ content. Fourier transform infrared (FT-IR) spectra showed two strong absorption peaks observed at lower frequency (∼435 to ∼800 cm −1 ), which can be assigned to the M–O (Mn, Co, and Fe) bonds. UV-Visible diffuse reflectance spectroscopy (DRS) shows that the energy band gap of pure MnFe 2 O 4 is 1.78 eV and with increase in the Co 2+ ion, it increases from 1.87 to 2.33 eV. Addition of Co 2+ in MnFe 2 O 4 reduces the particle size, which can be confirmed by the blue shift in the photoluminescence (PL) spectra. Vibrating sample magnetometer (VSM) results that confirmed a weak ferromagnetic behavior for all composition with saturation magnetization values in the range of 50.05 ±04 to 67.09 °03 emu/g. All composition of spinel Co x Mn 1− x Fe 2 O 4 nano-crystals were successfully tested as catalyst for the oxidation of benzyl alcohol to benzaldehyde, which has resulted 87.32 and 94.28 % conversion efficiency of MnFe 2 O 4 and Co 0.6 Mn 0.4 Fe 2 O 4 , respectively.