Preparation of graphene nanosheets by electrochemical exfoliation of a graphite-nanoclay composite electrode: Application for the adsorption of organic dyes

Abstract

A simple and cost-effective approach to get a few layers of graphene nanosheets is reported in this work. The electrochemical exfoliation of a graphite-nanoclay composite electrode, a pencil core, was carried out in the presence of Mohr's salt (ammonium ferrous sulfate solution) as an electrolyte and aluminum foil as a counter electrode. The unique property behind using this method was that the produced graphene colloid does not require any secondary physical processing or ultra-sonication for separation, as it raised over the electrolyte solution during the exfoliation process. To optimize the exfoliation conditions, different electrolyte concentrations (0.1, 0.5 and 1 M) and D.C bias voltages (7.5, 9 and 12 V) were investigated. The as-produced graphene nanosheets were filtrated, washed and characterized using Raman spectrometer, FT-IR, XRD, SEM and TEM, UV–vis spectrophotometer. The electrochemical exfoliation process was found to produce a few layers of graphene nanosheets with a lateral size ranged from 60 to 210 nm. Based on characterization results, especially Raman and TEM analysis, highly pure graphene nanosheets were obtained at 7.5 V and 0.5 M of electrolyte solution concentration. A promising application of the produced graphene sheets for cationic and anionic dye removal has been investigated. The removal efficiency of the prepared graphene against MO and MB was 22% and 77%, respectively.