SYNTHESIS AND CHARACTERIZATION OF EXTENDED GRAPHITE SHEET/ZnO NANOCOMPOSITE ELECTROCHEMICAL SENSOR FOR THE DETECTION OF PARA-NITROPHENOL

Abstract

Extended graphite sheet (EGS) and EGS/ZnO was prepared by chemical reduction method and Zinc oxide (ZnO) was prepared by precipitation methods. The as prepared nanomaterials were characterized by Uv-Vis, FTIR and XRD techniques to identify the crystalline phase, molecular interaction, functional group and band gap energy determination respectively. The electrochemical properties of EGS, ZnO, EGS/ZnO modified glassy carbon electrode (GCE) was investigated using cyclic voltammetry(CV) and electrochemical impedance spectroscopy (EIS) in the presence of 2 mM K3Fe(CN)6 + 0.1 M KCl and 0.1 M Phosphate buffer solution (PBS). The oxidation or reduction peaks of EGS, ZnO or EGS/ZnO modified GCE shows a slight increased after incorporating the nanomaterials at scan rates 50 mV/s. In the case of the EGS/ZnOnanocomposite the peak current enhanced due to the surface area and catalytic properties of graphite sheet and the conjugation of EGS to the ZnO nanoparticles enhanced the electron transfer. Therefore, EGS/ZnO/GCE was used as electrochemical sensor for the detection of para-nitrophenol in standard solution with differential pulse voltammetry (DPV). Effect of pH on EGS/ZnO/GCE sensor was optimized at (pH = 6.5) for the determination of paranitrophenol. The electrode was applied for the determination of p-Np in standard solution of 0.001 to 2 M. The sensor results in linear range of 0.01 to 2 M (R2 =0.998), limit of detection (LOD) was 0.00234μM and LOQ 0.0234μM with sensitivity of 0.00145µAµ M -1Cm-2 . The sensor was used to determine the level of p-Np in industrial waste water and showed a good reproducibility, stability and low effect of interference with recovery of 99%. Therefore, the developed sensor could be a good candidate for the detection of p-Np in different samples.