Solvothermal synthesis of CoS/reduced porous graphene oxide nanocomposite for selective colorimetric detection of Hg(II) ion in aqueous medium

Abstract

Metal sulphide nanoparticles (NPs) have great potential applications in environmental remediation as they can oxidize peroxidase substrates like 3,3ʹ,5,5ʹ-tetramethylbenzidine (TMB) due to the production of hydroxide radicals (OH) via the Fenton reaction in presence of H2O2. Their good binding affinity toward heavy metal ions through their S-containing sites, causes the blockage of the active sites of the catalyst and inhibits the oxidation process of peroxidase substrate. This property can be used for the sensing of heavy metal ions. Herein, a cobalt sulphide (CoS) decorated porous reduced graphene oxide (p-rGO) nanocomposite is proposed as a novel matrix for heavy metal ions detection in aqueous medium. The nanocomposite was fabricated by adopting a simple and easy solvothermal approach. After determination of the kinetics of the as-synthesized nanocomposite for the oxidation of TMB in presence of H2O2, the matrix was further used for the colorimetric detection of heavy metal (Hg, Pb, Cd) ions in aqueous medium. Depending on the metal ion, a detection limit of 14.23nM for Hg(II) could be reached. Furthermore, the synthesized nanocomposite was successfully utilized for the detection of heavy metal ions present in real samples.