Investigation of the electrochemical behavior of dopamine at electrodes modified with ferrocene-filled double-walled carbon nanotubes

Abstract

Electrochemical properties of a new class of endohedral functionalized carbon nanomaterial, ferrocene-filled double-walled carbon nanotubes (Fc@DWNTs) have been investigated by preparing an Fc@DWNTs modified glassy carbon electrode (Fc@DWNTs/GCE). In an aqueous LiClO4 solution, one pair of redox peaks corresponding to the surface-confined Fc+/Fc couple was observed, suggesting that Fc molecules encapsulated inside DWNTs retain their electrochemical activity. Moreover, the Fc@DWNTs/GCE showed good stability because DWNTs could overcome the leaching of Fc from the modified electrode. Electrocatalytic oxidation of dopamine (DA) at the Fc@DWNTs modified electrodes was also obtained, indicating that encapsulated Fc molecules can serve as good electron-transfer mediators. In addition, due to the peculiar structure of Fc@DWNTs, direct electroreduction of oxidation product of DA was also observed. An electrochemical sensor for DA has been constructed based on Fc@DWNTs and a kind of cation exchange membrane, Nafion, which played a key role in the selectivity of the sensor. Amperometric measurements were conducted in the presence of a large excess of ascorbic acid (AA). The limit of detection was found to be 0.3μM based on S/N of 3.