A simple and efficient nano-structured gold film sensor for gallic acidelectrochemical determination

A straightforward, rapid and green approach was proposed for the fabrication of goldnonporous film. A gold electrode was firstly oxidized under a high potential of 5 V, and ascorbicacid, as a nontoxic reducing agent, was then chosen to reduce the gold oxide. This process gives afractal gold nonporous film on the top of the gold electrode in a way of completely green chemistry. The nanostructure modified electrode greatly facilitates the electrochemical oxidationof Gallic acid (GA). As the gold nonporous film was formed in situ on the gold electrode,additional immobilization procedures are not necessary. A sensitive sensor can be easilydeveloped for the detection of GA. In the present study, the oxidation peak current of the GA in a0.10 M phosphate buffer solution was optimized for its determination by the differential pulsevoltammetry method. The variables which optimized include scan rate, step potential, and pH.Then, under the optimized conditions the dynamic range for GA 41 to 150 μM and thedetection limit was found to be 1.2 nM. Cyclic voltammetry and other electrochemical methodssuch as chronocoulometry, was used to investigate the electrochemical behavior of Gallic acid onthe gold nano-structured modified electrode. Using these methods, the diffusion coefficient (D =1.03 × 10−4 cm2 s−1) and the kinetic parameters such as the electron transfer coefficient (α =0.55) and exchanging current density (j0 = 4.28 cm−2) for GA were determined. The numberof proton and electron transfer for the oxidation of GA was investigated to be two protons andtwo electrons.

کلیدواژه ها:

Gold nano-structured film ، Gallic acid (GA) ، electro catalysis ، Cyclic voltammetry