Investigation on the electrochemical reduction process of HTeO2+ on Au substrate

The electrochemical reduction mechanism of tellurium on Au substrate from nitric acid solution containing HTeO₂ ⁺ ion was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The analyses indicated that the reduction of HTeO₂ ⁺ on Au substrate was an irreversible multi-step process and both HTeO₂ ⁺ ion and its intermediate product HTeO⁺ ion could all adsorb on Au substrate. The entire reduction process of tellurium on Au substrate can be considered as follows: 1) the initial electrochemical reactions: HTeO₂ ⁺ _(diss)+2e^-+2H⁺rarrHTeO⁺ _(ads) +H₂O, HTeO₂ ⁺ _(ads)+2e^-+2H⁺ rarr HTeO⁺ _(ads)+H₂O, HTeO⁺ _(ads) +2e^-+H⁺ rarr Te+H₂O; 2) the following chemical reactions: HTeO₂+_(diss) + Te + H⁺rarr2HTeO⁺ _(diss), HTeO⁺ _(diss) + Te+ H₂O rarr 2TeO^- _(diss)+3H⁺, 3) the subsequently electrochemical reactions: HTeO⁺ _(diss) + 2e^-+ H⁺rarrTe+H₂O, TeO^- _(diss)+ e^-+ 2H⁺ rarrTe+H₂O.