Electrochemical behaviour of tellurium and silver telluride at rotating glassy carbon electrode

Abstract

Electrodeposition of tellurium and silver is performed at rotating glassy carbon disc electrodes. First the mechanism of deposition of tellurium is investigated, and a well defined wave may be observed close to − 0.4 V/ sce. On the plateau of this wave a small peak may be noticed at − 0.7 V/ sce, and is due to reduction of Te(0) into Te(—II), but a chemical reaction occurs simultaneously between Te(—II) and Te(IV), reaching the electrode by convection and diffusion, to lead again to Te(0), and consequently the thickness of the deposit increases. Conversely, with a non-rotating electrode, the Te(IV) species reach electrode only by diffusion and in lesser amounts than in the above case; so the peak at − 0.7 V/ sce is large since the tellurium deposit dissolves by reduction int Te(—II). The electrodeposition of silver telluride Ag 2 Te is investigated with several concentration ratio of Ag(I) and Te(IV). One may observe the progressive changes in the shape and magnitude of the oxidation peaks of Ag and Te. For a Ag(I)Te(IV) ratio close to 0.8 it has been observed that quasi pure Ag 2 Te is obtained. The elementary composition of the deposit was confirmed by X-ray analysis.