ULTRAMICROELECTRODES - A NEW DIMENSION IN ELECTROCHEMISTRY

Not only quantitative, but also unusual qualitative effects accompany the drastic miniaturization of electrode surfaces. The term ultramicroelectrode is used when within the time scale of the experiment the already small diffusion layer becomes larger than the characteristic dimensions of the electrode. Whereas with macroelectrodes the diffusion field is planar, it is (hemi)cylindrical or (hemi)spherical with microelectrodes, depending on type (see sketch). N. S. Lewis and co-workers have now achieved a breakthrough in the miniaturization of microelectrodes: they can make so-called nanodes from plates with radii up to 1 nm.