THE ELECTROCHEMICAL REACTIONS OF TELLURIUM(IV) AT THE PLATINUM, TELLURIUM, AND PYROGRAPHITE ELECTRODES

Electroreduction of tellurium at platinum, pyrographite, and tellurium electrodes from tartrate electrolytes is studied by the cyclic voltam metry, rotating electrode, and rotating ring-disk electrode techniques . It is shown that, at all the materials studied, the tellurium electr odeposition occurs at an overvoltage; the process rate increases with the growing concentration of tellurium ions, lowering tartaric acid co ncentration, and diminishing solution pH. A kinetic equation for the r eaction Te(TV) --> Te(O) is proposed. At potentials more cathodic than -0.7 V vs. the silver-silver-chloride reference electrode, metallic t ellurium reduces yielding hydrogen telluride. The latter is capable of oxidizing at the electrode or interacting with the tellurium ions pre sent in the bulk solution. In the latter case, metallic tellurium form s, which then precipitates.