Studies on the electrodeposition behavior of selenium by electrochemical impedance spectroscopy and cyclic voltammetry

In this paper, the processes associated with the electrodeposition of Selenium on Au substrates from nitric acidic solutions were investigated by combined electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) measurements. The analyses reveal that H₂SeO₃ in the solution is firstly adsorbed on the surface of Au electrode during cathodic polarization and subsequently reduced to Se²⁺ by a two-electron reaction. Then the further reduction of Se²⁺ to Se⁰ occurs via the two-electron mechanisms at more negative potential. With the potential moving negatively, the electrodeposited Se⁰ on the surface of the electrode will be reduced to Se^2-. It is also observed that a chemical reaction will take place between the reduced Se^2- and H₂SeO₃ existing in the solution, which makes the electrodepositing process of Selenium more complicated.