Self-assembly of gold nanoparticles on sulphide functionalized polydopamine in application to electrocatalytic oxidation of nitric oxide

Abstract

A facile synthetic approach is used to prepare sulphide-functionalized polydopamine (S-PDA) via spontaneous self-polymerization of dopamine (DA) on glassy carbon (GC) substrate at room temperature. A GC electrode is immersed in a solution containing DA, carbon disulphide (CS2), triethylamine (TEA) and ethanol which renders the GC surface sulphide-functionalized. Subsequently, citrate-stabilized gold nanoparticles (AuNPs) are attached to the S-PDA/GC surface via Au–S linkages. Fourier transformed infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), UV–visible spectroscopy, field emission-scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and cyclic voltammetric analyses are used to confirm spontaneous attachment of AuNPs to the S-PDA/GC surface. The electrocatalytic activity of the as-synthesized AuNPs/S-PDA/GC electrode is studied for the oxidation of nitric oxide (NO) by employing cyclic voltammetric and chronoamperometric techniques. The AuNPs/S-PDA/GC electrode exhibits excellent electrocatalytic activity towards NO oxidation (0.489V) by reducing the oxidation overpotential from 0.293 and 0.176V with 2.5 times higher current sensitivity compared to S-PDA/GC (0.782V) and bare GC electrodes (0.665V) respectively. Further, the sensitivity and selectivity of the AuNPs/S-PDA/GC electrode are examined by using amperometry and the obtained results suggested that the proposed sensor probe exhibits excellent selectivity for NO in presence of commonly interfering biomolecules such as glucose, ascorbic acid, dopamine and uric acid along with very good reproducibility and long-term stability.