Dependence of Catalytic Activity of Nanocrystalline Nickel Ferrite on Its Structural, Morphological, Optical, and Magnetic Properties in Aerobic Oxidation of Benzyl Alcohol

Abstract

Nanocrystalline nickel ferrite spinel, NiFe2O4, with average crystallite size of 23.98 and 19.76 nm were successfully synthesized under sol–gel method (SGM) and microwave method (MM) conditions without using any surfactant or otherwise structure-directing (oxalic acid as the fuel) agents. Powder x-ray diffraction, high-resolution scanning electron microscopies indicate that single-crystalline nanoparticles are well-dispersed in the nickel ferrite. The elemental investigation of nickel ferrite was attained from energy-dispersive x-ray (EDX) analysis. Their optical properties (diffuse reflectance spectroscopy and photoluminescence) were described in depth in relative with their structural characteristics and the functionalization performance. After the magnetic measurements, samples showed a ferromagnetic behavior and the magnetization (Ms) value of NiFe2O4-MM is higher, i.e., 59.33 emu/g than NiFe2O4-SGM (50.12 emu/g). The magnetic properties could be further changed by controlling the shape, size, and crystallinity of the nanocrystals. Determination of concentration NiFe2O4 ions’ average number of atoms per nanoparticle was calculated by the new method as follows. Consequently, the designated procedure improves catalytic activity of nickel ferrite powders in aerobic oxidation of benzyl alcohol and catalytic reactions.