Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (12): 3212-3216.doi: 10.3866/PKU.WHXB20101218

• ELECTROCHEMISTRY • Previous Articles     Next Articles

Electrocatalytic Oxidation of Ascorbic Acid on a PPy-HEImTfa/Pt Electrode and Its Mechanism

LI Mei-Chao1,2, WANG Wu-Yang2, ZHU Wan-Xia1,2, MA Chun-An2   

  1. 1. Research Center of Analysis and Measurement, Zhejiang University of Technology, Hangzhou 310032, P. R. China;
    2. State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology, College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032, P. R. China
  • Received:2010-06-10 Revised:2010-08-24 Published:2010-12-01
  • Contact: LI Mei-Chao E-mail:limc@zjut.edu.cn
  • Supported by:

    The project was supported by the Natural Science Foundation of Zhejiang Province, China (Y4100647) and Analysis and Measurement Foundation of Zhejiang Province, China (2008F70029).

Abstract:

A platinum electrode was electrochemically modified with polypyrrole (PPy) in the ionic liquid 1-ethylimidazolium trifluoroacetate (HEImTfa) to produce a modified electrode (PPy-HEImTfa/Pt). Its electrocatalytic performance toward the oxidation of ascorbic acid (0.1 mol·L-1) was investigated by cyclic voltammetry. Compared with a bare Pt electrode and a PPy-H2SO4/Pt electrode, which was prepared in a solution of H2SO4, the peak potentials for ascorbic acid oxidation on the PPy-HEImTfa/Pt electrode decreased by 0.19 and 0.10 V, respectively. Additionally, the peak currents increased by 3.6 and 3.0 mA, respectively. Therefore, the electrocatalytic activity of the PPy-HEImTfa/Pt electrode for the oxidation of ascorbic acid was far better than that of the other systems. In situ Fourier transform infrared (In situ FTIR) spectroscopy results showed that the ascorbic acid was firstly oxidized to dehydroascorbic acid on the PPy-HEImTfa/Pt electrode and then underwent a fast hydration reaction to give hydrated dehydroascorbic acid in the aqueous solution. The hydrated dehydroascorbic acid then underwent further hydrolysis to form 2,3-diketogulonic acid by a ring opening reaction. Finally, a part of ascorbic acid was oxidized to CO2 at high potentials.

Key words: Electrocatalytic oxidation, 1-Ethylimidazolium trifluoroacetate, Polypyrrole, Ascorbic acid, In situ Fourier transform infrared spectroscopy

MSC2000: 

  • O643