Amperometric determination of nitrite by using a nanocomposite prepared from gold nanoparticles, reduced graphene oxide and multi-walled carbon nanotubes.

A nanocomposite consisting of gold nanoparticles (AuNP), reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) was synthesized using a co-reduction strategy in ethylene glycol using sodium citrate as the reducing agent. The nanocomposite was successfully characterized using X-ray powder diffraction, scanning electron microscopy and electrochemical methods. The material was deposited on a glassy carbon electrode and then was found to have high electrocatalytic capability for the electrode process of nitrite. This is attributed to the synergic actions of rGO, MWCNTs and AuNPs. Based on this, an amperometric nitrite sensing scheme was worked out that had attractive features: (a) a wide linear range that extends from 50 nM to 2.2 mM, (b) a working potential of 0.80 V (vs.SCE) at pH 5.0, (c) a 14 nM detection limit (at an SNR of 3), and (d) an electrochemical sensitivity of 1201 µA·mM-1·cm-2. The sensor was successfully applied to the determination of nitrite in the local river water. Graphical abstract Schematic presentation of the fabrication of the AuNPs-rGO-MWCNTs composite modified electrode and its application for the nitrite electrochemical sensing.