Fabrication and application of Gr/CNTs/AuNPs hybrid material in electrochemical sensor for determining the concentration of fenitrothion pesticide residues

Abstract

In this study, porous and non-porous graphene/carbon nanotube/gold nanoparticles (Gr/CNTs/AuNPs) hybrid material films were fabricated on copper substrates by chemical vapour deposition (CVD) method. The morphology, structure and electrochemical properties of the Gr/CNTs/AuNPs films were investigated via field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Raman spectroscopy, and electrochemical measurements. FESEM and TEM images show that the Gr/ CNTs/AuNPs hybrid film has a porous structure when the carbon source for the CVD process is a mixture of methane (CH₄) gas and the surfactant sodium deoxycholate (SDC) in solution containing AuNPs. The cyclic voltammetry (CV) characteristics show that the peak current of the electrode coated with porous Gr/CNTs/AuNPs film is 1.8 times higher than that of the electrode coated with non-porous Gr/ CNTs/ AuNPs film. The electrochemical impedance spectroscopy (EIS) also shows that the impedance of the porous sample is smaller than that of the non-porous sample. A sensor based on a porous Gr/CNTs/AuNPs film was used as an electrochemical platform for the determination of the residue concentration of the pesticide fenitrothion (Feni), and the limit of detection (LOD) of the sensor was estimated to be about 1.78x10^-2 ppb within a concentration range of 10^-2-10 ppb.