Abstract
The electrochemical synthesis of three-dimensional (3D) polyaniline (PAN) network structure on 3-aminobenzenesulfonic acid (ABSA) functionalized glassy carbon electrode (GCE) and its electro-catalytic oxidation towards ascorbic acid (AA) had been studied. ABSA was first covalently grafted on GCE surface via the direct electrochemical oxidation of ABSA on GCE, which was followed by the electrochemical polymerization of aniline on the ABSA functionalized GCE. Then PAN-ABSA composite film modified GCE (PAN-ABSA/GCE) was obtained. Scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS) and electrochemical techniques had been employed to characterize the obtained electrodes. Due to the effective doping of ABSA in PAN, the redox electro-activity of PAN had been extended to neutral and even the basic media, thus, the PAN-ABSA composite film modified GCE could be used for electro-catalytic oxidation of AA in 0.1 M phosphate buffer solution (PBS, pH 6.8). At PAN-ABSA/GCE the oxidation over-potential of AA shifted from 0.39 V at GCE to 0.17 V with a greatly enhanced current response. The electro-catalytic oxidation peak current of AA increased linearly with the increasing AA concentration over the range of 5.00 × 10-4-1.65 × 10-2 M with a correlation coefficient of 0.9973. The detection limit (S/N = 3) for AA was 1.16 × 10-6 M. Chronoamperometry had also been employed to investigate the electro-catalytic oxidation of AA at PAN-ABSA/GCE. The modified electrode had been used for detecting AA in real samples with satisfactory results.
Highlights
As a conducting polymer, PAN has received much interest due to its facile synthesis, good environmental stability, ease of conductivity control by changing the oxidation and protonation states and inexpensive monomers [1,2,3,4]
Preparation of glassy carbon electrode (GCE) Previous workers have reported that the pre-treated GCEs by using chemical and/or electrochemical procedures exhibit somewhat electro-catalytic effect towards the redox of some electro-active substances, and indicated that this catalytic property has been resulted from the generation of oxygen-containing functional groups [11,12,24,25]
We aimed to investigate the electrochemical activity and electrocatalysis of PAN doped by sulphonic acids groups in aminobenzenesulfonic acid (ABSA) molecules, it’s necessary to avoid the influence of these oxygen-containing functional groups on GCE surface
Summary
PAN has received much interest due to its facile synthesis, good environmental stability, ease of conductivity control by changing the oxidation and protonation states and inexpensive monomers [1,2,3,4]. These properties make it attractive for certain applications, such as energy conversion, electrochromic devices, sensors, corrosion prevention [5,6,7] and electrocatalysis [8,9,10,11]. To extend its application in solutions with higher pH values, three kinds of methods have been explored and used widely: the first way of improving the pH dependence of PAN reactivity was performed by using the sulfonation of PAN with
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