The electrochemistry of tellurium in methylene chloride

It was found that TeCl₄ in methylene chloride (containing tetrabutylammonium perchlorate as a supporting electrolyte) is reduced to TeCl₂, Te⁰ and Te^-2 in potential applied. Two reduction waves are observed during the reduction of TeCl₄ at a platinum rde (Ep₁ = 0.08 ± 0.02 V, Ep₂ = -1.10 ± 0.02 V) due to the reduction of TeCl₄ to Te and Te^-2 respectively. A cathodic deposition of tellurium from TeCl₄ is followed by anodic stripping wave (Ep₁ = 0.42 ± 0.02 V), corresponding to the oxidation of Te to TeCl₂. It has been shown that reduction of TeCl₄, or TeCl^-2₆ to Te causes coating of the electrode with metallic tellurium, on whose surface chloride ions are strongly bonded. It was found that when the electrolysis solution contains excess of chloride ion with respect to Te^IV the peak potentials of the cathodic waves shift to more cathodic values (Ep₁ = 0.30 ± 0.02 V, Ep₂ = -1.25 ± 0.02 V). After cathodic deposition of at least a monolayer of tellurium from such a solution two anodic waves appear (Ep₁ = 0.12 ± 0.03 V, Ep₂ = 0.24 ± 0.03 V) which are both due to the oxidation of Te to Te^II.