Excellent electrocatalytic activity of Au nano-flowers towards oxidation of sulfite: Application to electrochemical detection of sulfite in environmental samples

Today, development of nanotechnology has proved that noble metal nanoparticles show improved catalytic behaviour compared to their bulk materials due to their smaller size and the nano-effect [1]. This improved catalytic performance encourages the scientists to use these nanoparticles in the design of new electrochemical sensors. Sulfite is an anti-oxidant agent widely used as an additive to prevent from oxidation and bacterial growth during the storage offoodstuffs. However, due to its toxic effects, FDA has regulated limitations on the amount of sulfite in foodstuffs [2-3]. Therefore, detection of sulfite is of paramount importance in food quality control process. In this work, electrocatalytic activity of flower-like Au nanoparticles towards electrochemicaloxidation of sulfite has been investigated. Citrate stabilized Au nanoparticles (AuNPs) has been covered on a low cost and disposable gold DVD electrode via a self-assembly monolayer of Lcysteine (SAM) as linker. The characteristics of AuNPs were investigated using UV-Vis spectroscopy, particle size and scanning electron microscopy and the flower-like morphology of AuNPs was confirmed by atomic force microscopy. Electrochemical impedance spectroscopy experiments proved the electrocatalytic activity. Electrochemical oxidation of sulfite at thesurface of the modified electrode was investigated using cyclic voltammetry showed the decreased oxidation overpotentials and increased current response of the sulfite compared to the bare Au and DVD electrodes. Square wave voltammetry is used for quantitative measurementsafter careful optimization of influential operating conditions such as the amount of AuNPs and the pH of the solution. The analytical applicability of the proposed electrode was demonstrated by determination of sulfite in water and beverages.

کلیدواژه ها:

Sulfite ، Flower-like Au nanoparticles ، Gold DVD ، Voltammetry