Detection of 3,4-diaminotoluene based on Sr0.3Pb0.7TiO3/CoFe2O4 core/shell nanocomposite via an electrochemical approach
Control of the sol–gel shell coating is important in the development of core–shell magnetic nanocomposites. Herein, we explored a scalable sol–gel method for the preparation of an Sr0.3Pb0.7TiO3/CoFe2O4 core–shell magnetic nanocomposite (SPT/CFO MNc) with a finely controlled shell and evaluated its efficiency as an electrochemical sensor. Firstly, CoFe2O4 nanoparticles were obtained via a citrate sol–gel method and sintered at 700 °C. Subsequently, Sr0.3Pb0.7TiO3 was applied to the CoFe2O4 nanoparticles to allow the formation of shells. The X-ray diffraction results indicated that the core nanoparticles have a cubic CoFe2O4 spinel structure and high-resolution transmission electron microscopy and scanning electron microscopy confirmed the successful formation of a uniform and thin Sr0.3Pb0.7TiO3 shell. The magnetic hysteresis loops confirmed the ferromagnetic nature of the as-prepared magnetic nanocomposite, which exhibited a saturation magnetization of 4 emu g−1 and coercive field of 600 Oe. An electrochemical sensor selective toward 3,4-diaminotoluene was fabricated by coating the synthesized Sr0.3Pb0.7TiO3/CoFe2O4 core–shell magnetic nanocomposite onto a glassy carbon electrode. Detailed experimental analyses were performed to assess the analytical parameters of the proposed sensor. The calibration curve of 3,4-diaminotoluene was obtained by plotting the linear relation of current versus 3,4-DAT concentration. According to the slope of the calibration curve, the sensor sensitivity was calculated to be 24.3323 μA μM−1 cm−2 by considering the surface area of the glassy carbon electrode (GCE: 0.0316 cm2). The linear dynamic range was estimated by considering the linear part of the calibration curve, which was found to be 0.1 nM–0.01 mM (linear dynamic range). Based on the signal-to-noise ratio of 3, the detection limit (96.09 ± 4.80 pM) and limit of quantification (320.3 pM) were calculated. Furthermore, effective and satisfactory results were obtained in the analysis of environmental samples.