Electrochemical Event of Single Redox Latex Particles

The steady-state diffusion-controlled current of polyaniline-coated polystyrene latex particles suspended in water contained a periodic wave with a typical frequency of 14 Hz. The latex particles were monodispersed spheres, 2.6 μm in diameter. They were composed of cores of polystyrene on which a 0.4 μm thick redox active polyaniline film was coated. From the polyaniline layer of one particle, 5 × 1010 electrons were transferred in the electrode reaction. The polyaniline showed the same electrochemical behavior as the conventionally electrodeposited polyaniline. The oxidation current of the suspension was controlled by diffusion. Although the oxidation current contained noise from the electric power source, its Fourier transformation exhibited a clear band, indicating that the particles had collided with the electrode at a given frequency, governed by thermal fluctuation, to be oxidized. The frequency had a linear relationship with the concentration of latex. It was invariant to the electrode potential an...