Ex situ atomic force microscopy of bismuth film deposition at carbon paste electrodes

This paper describes how the surface of an oil-graphite based carbon paste electrode (CPE) can be studied by means of atomic force microscopy (AFM). By choosing the scanning parameters very carefully, it is possible to scan even such a soft and delicate surface. Both intermittent contact and phase shift scan modes provide useful information about nano-distribution of topographical details as well as hard and soft areas on the surface. The electrochemical bismuth film deposition from a 0.05 M sulphuric acid +1 ppm Bi(III) containing electrolyte can be investigated by both scan modes. Intermittent scan mode yields very thin (2 nm) layer-shaped structures sizing from 20 nm to some microns. Phase shift scans of the same sections depict extensive areas of high and uniform phase shift, which cannot be found on the bare CPE, and thus have to be attributed to the newly formed bismuth film. AFM holds great promise for the investigation of all kinds of carbon paste electrodes.