Electrochemistry at the level of a single conducting particle in the micrometric range. a new technique for characterizing the components of a mineral pulp grain after grain

摘要

To study samples of divided conducting materials, electrochemists have to use carbon paste electrodes. However, the electrochemical behaviour of the samples may be deeply affected by the presence of supporting electrolytes at high concentrations, by the binder used for the carbon paste preparation or by the carbon particles in the vicinity of the material. We have developed a new electrochemical technique which allows examination of single conducting particles without external disturbance. It consists of using a conducting particle (10-100 mu m) as working electrode. Particles are placed on a microporous separator soaked by capillarity by an electrolytic solution or even by milli-Q water without supporting electrolyte. The electric contact with the selected particle is made with a carbon fibre under a microscope. The technique was successfully used for the characterization of pyrite grains which have reacted with heavy metals (mercury, silver ...) or phenolic compounds and for the examination of the voltammetric behaviour of silver selenide.