The fabrication of a new modified pencil graphite electrode for the electrocatalytic reduction of 2-nitrophenol in water samples

Abstract

In this study, we report a sensitive modified pencil graphite electrode prepared by easily coating with 3-amino-1,2,4-triazole-5-thiol (3AT5T) for the selective determination of 2-nitrophenol (2-NP) by differential pulse voltammetry (DPV) method. The electrochemical methods, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), were applied to characterize this modified electrode in the mixture of K4[Fe(CN)6]/K3[Fe(CN)6] containing 0.1 M KCl as redox probe. Further, the electrode was characterized by Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). PGE demonstrated a remarkable increment in the redox probe's peak current, due to the effective electroactive surface area at the modified PGE (2.278 cm2) when it was compared with the bare PGE (0.128 cm2). This modified PGE was successfully used for the electrocatalytic reduction of 2-NP at pH 4.5 in 0.1 M phosphate (PBS) buffer. The reduction current response of 2-NP at the modified PGE was increased at about 8 times compared with the bare PGE. From the DPV analysis, under the optimized conditions, the reduction peak currents were increased linearly with two concentration intervals of 2-NP at pH 4.5 in PBS buffer. One of them is 45 nM–560 μM and the other is 560 μM–2 mM. The limit of detection (LOD) is found as 14.1 nM for 2-NP (S/N = 3). The fabricated PGE was tested in water samples for the practical utilization. From the results, it was pointed that the modified PGE can be used as an environmental sensor in analytical applications.