Highly sensitive and selective amperometric hydrazine sensor based on Au nanoparticle-decorated conducting polythiophene prepared via oxidative polymerization and photo-reduction techniques

Abstract

In this study, gold nanoparticles (AuNPs) decorated polythiophene (Pth) nanocomposite modified glassy carbon electrode (GCE) has been used to fabricate an electrochemical sensor for the sensitive and selective detection of hydrazine. Transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) were used to adequately characterize the nanocomposite. The research findings revealed that AuNPs with cubic phase and diameter range 10–22 nm were monodispersed over the polymeric surface. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) investigation demonstrated that the AuNPs decorated Pth greatly improved the electrocatalytic performance compared with pure Pth modified GCE. This extraordinary electrochemical property is attributed to the synergistic coupling effect between AuNPs and Pth. The mechanistic analysis using CV voltammograms measured in varying scan rates revealed irreversible diffusion-controlled kinetics involving four-electron (4e−) transfer process of hydrazine oxidation. In amperometric (i-t) detection, the proposed sensor showed high sensitivity 0.1817 μAμMcm−2 and a low detection limit 0.77 μM (S/N = 3) over the concentration range 1–963 μM. Moreover, this proposed nanocomposite-based sensor was highly selective toward hydrazine in the presence of common interfering species, especially in high concentrations of sugars (e.g. glucose, sucrose, fructose, and galactose) and exhibited promising analytical results of recovery tests in water samples with acceptable recovery with a relative standard deviation less than 5%.

Keywords

• AuNPs
• Polythiophene
• Hydrazine sensor
• Amperometry
• Selectivity