Monodispersed Au nanoparticles decorated graphene as an enhanced sensing platform for ultrasensitive stripping voltammetric detection of mercury(II)

We demonstrate a new highly sensitive and selective Hg(II) sensor with a graphene-based nanocomposite film as the enhanced sensing platform. The platform was constructed by homogenously distributing monodispersed Au nanoparticles (AuNPs) onto the two-dimensional (2D) graphene nanosheet matrix. Its surface structure and electrochemical performance were systematically investigated. Such a nanostructured composite film platform could combine with the advantages of AuNPs and graphene nanosheets, greatly facilitate electron-transfer processes and the sensing behavior for Hg(II) detection, leading to a remarkably improved sensitivity and selectivity. The detection limit was found to be as low as 6 ppt (S/N = 3), much below the guideline value from the World Health Organization (WHO). The interference from other heavy metal ions such as Cu2+, Cr3+, Co2+, Fe3+, Zn2+ and I− ions associated with mercury analysis could be effectively inhibited. The performance of new sensor was also evaluated by the direct detection of Hg(II) in river water specimens, suggesting it is very promising for practical environmental monitoring applications.