Impedance study of the electrochemical reduction of adrenochrome on glassy carbon |
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Authors: | Zhanjun Zhang Jing Huang Xizum Wu Wenzhi Zhang Songying Chen |
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Institution: | 1. Lab. 205, Department of Chemistry, Hebei Teachers''s University, Shijiazhuang, Hebei 050016 People''s Republic of China;2. Institute of Coal Chemistry of the Academy of Science of China, Taiyuan, Shanxi 030001 People''s Republic of China |
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Abstract: | The electrochemical reduction of adrenochrome on a glassy carbon electrode was investigated by ac impedance in a constant ionic strength McIlvaine buffer solution. When the frequency was lower than 60 kHz, —Z″ against Z′ showed straight lines whose inclined angles with the real axis were within the range 71–76° in the diagrams of the complex impedance plane obtained at different do potentials. In the corresponding admittance diagrams, distorted semicircles appeared. The electrode reaction involves adsorption of electroactive species and the effect of concentration polarization cannot be neglected. Based upon the admittance model of the equivalent circuit, the optimal estimated values of some model parameters were obtained by using a Gauss-Newton algorithm and non-linear curve fitting. The characteristics of the electrode process are also discussed. |
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Keywords: | Adrenochrome Electrochemical reduction Weak adsorption Impedance Admittance |
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