Non-enzymatic electrochemical sensor for nitrite based on a graphene oxide–polyaniline–Au nanoparticles nanocomposite

Abstract

Although non-enzymatic electrochemical methods are advantageous for the detection of nitrite, a highly toxic pollutant, improved sensitivity is required for practical applications. Herein, a graphene oxide–polyaniline–Au nanoparticles (GO-PANI-AuNPs) nanocomposite prepared by a hydrothermal synthesis method was used to fabricate a novel electrochemical nitrite sensor. Structural and morphological characterisation of the nanocomposite using transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy revealed that PANI formed a network structure on the GO surface and that a large amount of AuNPs were uniformly connected to the active sites of GO-PANI. Electrochemical investigations showed that the fabricated GO-PANI-AuNPs sensor exhibited excellent catalytic performance for the oxidation of nitrite. The sensor showed good selectivity for nitrite with linear ranges of 0.5 μM–0.24 mM and 0.24 mM–2.58 mM and a detection limit of 0.17 μM (signal-to-noise ratio of 3). This developed sensor was successfully applied to the detection of nitrite ions in tap water and sewage, and the recovery rate was 97%–105%. Therefore, the GO-PANI-AuNPs nanocomposite offers a reliable electrochemical strategy for the detection of NO2−, which has important theoretical and practical significance for environmental monitoring applications.