Electrochemical detection of 4-nitrophenol based on a glassy carbon electrode modified with a reduced graphene oxide/Au nanoparticle composite

A new electrochemical sensor for 4-nitrophenol (4-NP) detection based on the reduced graphene oxide (RGO) and Au nanoparticle composite was developed. The RGO film was first electrodeposited onto a glassy carbon electrode (GCE). Then Au nanoparticles (AuNPs) were electrochemically deposited onto the RGO film. The morphology and electrochemical properties of the AuNP/RGO composite were investigated. The synergic effect of AuNPs and RGO nanosheets as co-modifiers greatly facilitates electron-transfer processes between the electrolyte and the GCE, and thus leads to a remarkably improved sensitivity for 4-NP detection. Two detection modes, differential pulse voltammetry (DPV) and square wave voltammetry (SWV), were applied. A wide linear range of values, 0.05-2.0 mu M and 4.0-100 mu M for DPV and 0.05-2.0 mu M for SWV, were obtained. The limit of detection (LOD) of 4-NP was 0.01 mu M and 0.02 mu M for DPV and SWV, respectively. This sensor was successfully used in the detection of real water samples from Xiangjiang River.