Nanostructure Restoration of Thermally Reduced Graphene Oxide Electrode upon Incorporation of Nafion for Detection of Trace Heavy Metals in Aqueous Solution

Abstract

High performance reduced graphene oxide (RGO)‐Nafion (N) thin film electrodes coated on silicon (Si) substrates (RGO‐N/Si) were successfully developed through thermal reduction of GO‐N without delamination from the substrates. The restoration of the RGO‐N nanostructure upon the addition of Nafion was proven by Raman spectroscopy (RS) and field emission scanning electron microscopy, and the restoration mechanism of the RGO‐N nanostructure was proposed. Through the investigation using x‐ray photoelectron spectroscopy (XPS), the polyfluorocarbon from Nafion possessed a function that could prevent the delamination of the RGO sheets from the substrates during the thermal reduction. The RGO‐N/Si samples were later used for the determination of trace heavy metals, such as divalent lead, cadmium and copper ions (Pb2+, Cd2+ and Cu2+, respectively) using square wave anodic stripping voltammetry in a 0.1 M acetate buffer solution (pH 5). Based on the electroanalytical measurements, the RGO‐N/Si samples exhibited a highly linear behavior in the detection of Cd2+, Pb2+ and Cu2+ over the concentration range of 50 nM to 300 nM with detection limits at nM levels. In addition, the RGO‐N/Si samples presented good recoveries of target metals in tap water samples.

Application of Graphene and its Derivatives in Detecting Hazardous Substances in Food: A Comprehensive Review

“…In this method, inorganic strong protic acids (such as concentrated sulfuric acid, concentrated HNO 3 , or a mixture) are used to treat the raw graphite. Small molecules of a strong acid are inserted in between the graphite layers, followed by strong oxidants such as KMnO 4 and KCIO 4 ( Lee et al, 2016 ). Finally, hydrogen peroxide is used to remove any excess KMnO 4 .…”