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

•The Ni1-xMgxFe2O4 (0 ≤ x ≤ 0.5) were prepared by microwave combustion method.DRS-UV studies were performed to study the optical behavior of nickel ferrites.•Magnesium doped nickel ferrite samples exhibit ferromagnetic behavior.•The probable photocatalytic degradation mechanism is discussed. 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%.