Abstract
Synthesis of Y(III) phosphate-functionalized polyaniline nanocomposite (PANI@Y(III)PO4) was achieved through sol–gel method. The synthesized PANI@Y(III)PO4 was characterized by various techniques including Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FE-SEM), Energy dispersive X-ray spectroscopy (EDX), X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), Thermogravimetric analysis (TGA)-Differential thermal analysis (TGA-DTA) and direct current (DC) electrical conductivity. Efficient employment for the nanocomposite as modifier glassy carbon electrode was characterized by electrochemical impedance spectroscopy (EIS) and cyclicvoltametry (CV). The modified electrode showed a powerful enhancing effect and great stability in electrochemical sensing of the heavy metal ion Pb(II), giving an anodic peak current with a formal potential of - 0.195 V in acetic solution. The electrochemical parameters of the proposed sensor such as exchange current density (ⅉ0), active surface area of PANI@Y(III)PO4 modified GCE (A), surface coverage (Γ) of Pb (II) on the surface of PANI@Y(III)PO4, transfer coefficient (α) and number of electrons (n) involved in the electro-reduction, were found to be 92.21 μA cm-2, 0.27 cm2, 3.24×10-7 mol cm-2, 0.26 and 1.6 ≈ 2, respectively. Two voltametric techniques namely CV and linear sweep voltammetry (LSV) studies exhibited that the anodic peak current was linearly dependent on the concentration of Pb(II) with a broad dynamic range of 2.85–199.92 μM and 2.85–62.85 μM, respectively. However, the LSV method showed the highest sensitivity (5.58 μA μM-1 Cm-2) and the lowest detection limit (0.04 μM).