Fe₃O₄-Polyaniline Nanocomposite for Non-enzymatic Electrochemical Detection of 2,4-Dichlorophenoxyacetic Acid

This study proposes the development of an electrochemical sensor based on fabrication of a glassy carbon electrode (GCE) with Fe₃O₄-polyaniline (Fe₃O₄-PANI) nanocomposite, which was further used for enzyme-less detection of 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous medium. Spectroscopic studies, microstructural studies, and elemental analysis established the formation of Fe₃O₄ nanoparticles with polyaniline coating. The fabricated Fe₃O₄-PANI-GCE was characterized by electrochemical techniques like cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical response of 2,4-D on Fe₃O₄-PANI-GCE was evaluated by performing cyclic voltammetry and amperometry experiments. The synergistic effect of the composite causes the superior electrochemical behavior of Fe₃O₄-PANI-GCE toward the detection of 2,4-D. Amperometric measurements exhibited a linear concentration range from 1.35 to 2.7 μM. The sensitivity and detection limit were evaluated from the amperometric responses, which were found to be 4.62 × 10^-7 μA μM^-1 cm^-2 and 0.21 μM, respectively. The electrochemical sensing response could be attributed to adsorption of 2,4-D onto the Fe₃O₄-PANI-modified GCE (Fe₃O₄-PANI-GCE) surface. Fe₃O₄-PANI-GCE is found to be a simple, low-cost, and biocompatible non-enzymatic sensor for detection of 2,4-D in aqueous medium at ambient temperature.