Preparation and Electrochemical Response of 1-3 nm Pt Disk Electrodes.

The preparation and characterization of Pt nanoelecirodes in the range of 1 to 3 nm in radii are reported. A Pt microwire is sealed into a bilayer quartz capillary and pulled into an ultrasharp Pt nanowire sealed in a silica tip using a laser-assisted puffing process. The ultrasharp tip is then sealed into a piece of glass tubing, which is manually polished to expose the Pt. Transmission electron microscopy and steady-state voltammetry are utilized to characterize the nanoelectoxles. The results show that the minimum size of the Pt nanoelectrode is determined by the size of the Pt microwire and parameters used in the putting process. The heterogeneous electron transfer rate constant for the oxidation of ferrocene, ferrocenemethanol, and potassium hexachioroiridate (III) are determined from steady-state voltanunetmy using the method of Mirkin and Bard and are found to be k° = 7.6 ± 3.4 cm/s and a = 0.85 ± 0.06 for ferrocene, k° = 7.4 ± 6.9 cm/s and a = 0.78 ± 0.16 for ferrocenemethanol, and k° = 6.0 ± 4.2 cm/s and a 0.72 ± 0.15 for IrCl63-. [ABSTRACT FROM AUTHOR]