Synthesis and application of mixed-spinel magnesioferrite: structural, vibrational, magnetic, and electrochemical sensing properties

Abstract

This article presents an efficient non-enzymatic electrochemical sensor based on catalytic oxidation by the MgFe₂O₄ magnetic spinel for the sensitive determination of ascorbic acid. MgFe₂O₄ spinel ferrite is synthesized via the simple and cost-effective solid-state reaction route. X-ray photoelectron spectroscopy and X-ray diffraction studies reveal a mixed spinel structure of the synthesized material with the formula (Mg_0.65Fe_0.35)_A[Fe_1.65Mg_0.35]_BO₄ with Fe³⁺ and Mg²⁺ occupying both the tetrahedral and octahedral sublattices. The Raman and Fourier-transform infrared spectroscopic analyses confirm the spinel structure formation. The DC magnetic measurements reveal a soft-magnetic behavior of the material due to the cationic distribution in the tetrahedral and octahedral sublattices. A maximum magnetization of 33.3 emu g⁻¹ at 70 kOe is obtained for the hysteresis loop measurement, which is performed at a temperature of 10 K. Furthermore, the magnesioferrite spinel integrated glassy carbon electrode displays an enhanced catalytic activity toward ascorbic acid compared to the bare electrode in the phosphate buffer solution of pH 7.4 owing to the mixed-valence cationic states in the spinel ferrite. The electrochemical performance of the modified electrode under the influence of various parameters such as scan rate, analyte concentration, and interference are studied in detail. The sensor provides a linear increase in the oxidation peak current as a function of increasing concentration with a limit of detection and quantification of 24.09 μM and 80.30 μM, respectively. The synthesized ferrite shows good selectivity toward interfering agents, such as potassium chloride, sulfuric acid, hydrogen peroxide, sodium hydroxide, glucose, and choline chloride.