Nanocomposite of graphene based sensor for paraquat: Synergetic effect of nano-gold and ionic liquids on electrocatalysis

Abstract

A solution-based approach of chemical co-reduction of graphene oxide (GO) and HAuCl₄ was used to prepare graphene/Au nanocomposite (GR/Au). The resulting hybrid material was characterized by scanning electron microscope and transmission electron microscope, which demonstrated that Au nanoparticles could been uniformly deposited on the GR sheets. Then, nanocomposite (GR/Au/ILs) of ionic liquids (ILs), GR and Au nanoparticles (NPs) were successfully prepared. Such a nanostructured composite greatly facilitated electron-transfer process and the sensing behavior for PQ detection, leading to remarkably improved sensitivity. The GR/Au/ILs modified glassy carbon electrode showed a broad linear range from 2.0 × 10⁻⁹ mol L⁻¹ to 1.0 × 10⁻⁷ mol L⁻¹, with a detection limit of 7.3 × 10⁻¹⁰ mol L⁻¹ (S/N = 3) for PQ, along with good reproducibility and stability. At the same time, this sensor could be applied to the determination of PQ in real samples with satisfactory results.