Transparent films from carbon nanotubes/Prussian blue nanocomposites: preparation, characterization, and application as electrochemical sensors

Abstract

The preparation of a homogeneous, transparent and electroactive film of a carbon nanotube/Prussian blue nanocomposite is described for the first time. Transparent films of iron- and iron oxide-filled multi-walled carbon nanotubes (CNTs) were prepared on top of ITO electrodes from NMP dispersions of CNTs. Prussian blue (PB) was electrosynthesized as nanocubes over the CNT walls through a heterogeneous reaction between ferricyanide ions in an aqueous solution and the iron-species encapsulated into CNTs. The resulting nanocomposites exhibited intimate contact between PB and CNTs, which improved the stability and redox properties of PB. The electrodeposition of PB and the chemical interaction between PB and CNTs were confirmed by cyclic voltammetry, X-ray diffraction, UV-Vis and Raman spectroscopies and Raman spectroelectrochemistry. The amount of PB obtained in the films was directly proportional to the amount of CNTs deposited initially. In addition, these electrodes were employed as hydrogen peroxide amperometric sensors, which demonstrated very low detection limits (4.60 × 10⁻⁹ mol L⁻¹) and very high sensitivity (97.2 A cm⁻² M⁻¹).