Developments in Nanowire Scanning Electrochemical - Atomic Force Microscopy (SECM-AFM) Probes

Since its introduction, SECM-AFM has gained recognition as an extremely useful tool for a wide variety of analytical and imaging applications. We have developed a probe fabrication method that uses single-walled carbon nanotube bundles as a structural template for the formation of a nanowire at the apex of an AFM tip. Subsequent insulation of the probe and cutting across the nanowire yields a disc electrode of well-defined geometry. The probe apex geometry results in topographic information being obtained without causing damage to the electrode by contacting the substrate. Also, by placing the electrode at the apex, electric force imaging can also be realized. The probes are demonstrated to accurately identify active sites and locally generated species by combined topographic and electrochemical measurements on the sub-micron scale. The influence of the probe geometry on the diffusion of species from micrometer scale active sites will also be considered.