Ferrocene peapod modified electrodes:: Preparation, characterization, and mediation of H2O2

Electrochemical properties of a new nanomaterial ferrocene (Fc) peapod, Fc-filled single-walled carbon nanotubes (Fc@SWNTs), have been investigated in an aqueous solution in detail by preparing different kinds of Fc@SWNTs-modified glassy carbon electrodes (Fc@SWNTs/GCE and Fc@SWNTs-gel/GCE). One pair of surface-confined redox waves corresponding to the couple of Fc/Fc(+) is obtained, which indicates that Fc encapsulated inside SWNTs retains electrochemical activity. The Fc@SWNTs-gel/GCE shows better electrochemical reversibility due to the existence of room temperature ionic liquid (RTIL). Furthermore, it shows excellent mediation of H2O2 based on Fc/Fc(+) used as electron-transfer mediators for oxidation of H2O2 to O-2 and reduction to H2O, suggesting specific properties of Fc@ SWNTs due to a combination of Fc and SWNTs. The interaction between Fc and SWNTs is also characterized by UV-vis-NIR spectrometry and Raman spectrometry. A Fc@SWNTs-based sensor for H2O2 with a determination limit of 5 AM is fabricated, and it shows good stability and reproducibility. This work not only demonstrates that the Fc peapod is a new kind of functional nanomaterial but also appears promising in constructing novel chemical and biosensors and fuel cells.