Enhanced optical, magnetic, and photocatalytic activity of Mg2+ substituted NiFe2O4 spinel nanoparticles

Abstract

Magnesium doped nickel ferrite spinel nanostructured were prepared using a microwave combustion method. The structural characterization by XRD analyses confirmed that undoped NiFe2O4 showed a single phase cubic spinel structure. However, with increasing Mg2+ concentration in the range 0.1 to 0.5 induced the crystallization of secondary α-Fe2O3 phase. The cubic nanostructured exhibited an average crystallite size between 20 and 35 nm. The presence of tensile/compressive strain in Mg2+ doped NiFe2O4 was determined from Williamson–Hall (W–H) method. The appearance of FT-IR bands at around 435, 459, and 581 cm−1, characteristics of spinel cubic and rhombohedral stretching modes. The optical band gap as determined by diffuse reflectance spectroscopy (DRS) decreases with increasing Mg2+ content due to the quantum confinement effect. Surface morphology showed nanosized crystalline grains agglomerated with spherical shapes and energy dispersive X-ray analyses was used to examine the elemental composition of the Mg2+ doped NiFe2O4 spinel nanoparticles and confirmed the presence of nickel, magnesium, iron and oxygen elements. Magnetization–Field (M − H) hysteresis curves revealed the appearance of ferromagnetic behavior at room temperature. The as-fabricated Mg2+ doped NiFe2O4 spinel nanostructures were evaluated for the photocatalytic degradation of rhodamine B under visible light irradiation for atmospheric conditions. When a small amount of H2O2 was added during photocatalysis, indicating the samples possessed photo-Fenton like catalytic activity. This type of spinel nanoparticles behaves as an efficient catalyst with high efficiency around above 99%.