A 3D composite of gold nanoparticle-decorated MnO2-graphene-carbon nanotubes as a novel sensing platform for the determination of nitrite

A novel 3D composite of gold nanoparticle (AuNP)-decorated MnO 2 -graphene (GP)-carbon nanotube (CNT)-modified glassy carbon electrode (GCE) was fabricated by drop casting the as-synthesized AuNP/MnO 2 -GP-CNT suspension onto the surface of GCE. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images indicate the successful formation of AuNPs/MnO 2 -GP-CNT composite step by step from the precursor of CNTs. The cyclic voltammetry (CV) results show the AuNPs/MnO 2 -GP-CNTs/GCE exhibits superior electrocatalytic activity towards oxidation of nitrite in a 0.1 M phosphate-buffered saline (PBS, pH 7.0) compared to the MnO 2 -GP-CNTs/GCE. The result of amperometric response indicates that the AuNPs/MnO 2 -GP-CNTs/GCE can be used to determine nitrite concentration in a wide linear range of 1.0 and 2896 μM with a detection limit of 0.05 μM. The developed method can be successfully applied for determination of nitrite in water samples.