Kinetic study of Ga electrodeposition on different configuration of Cu cathodes

Abstract

• The steady-state polarization of Ga electrodeposition at Cu cathode is researched accompanied by HER. • Cu foam narrows the Tafel region but hardly change the kinetic parameters. • Hydrogen bubbles enhance the mass transfer process and cause the increase of limiting current density. • The transformation of electrode surface at early stage affects Ga electrodeposition. Different configuration of Cu cathodes (Cu plate and Cu foam) has been applied for Ga electrodeposition due to the low hydrogen evolution activity of copper. It is found that Ga electrodeposition is controlled by electrochemical reaction step at low current densities and by mass transport step at high current densities. The steady-state polarization process of Ga electrodeposition accompanied by hydrogen evolution is researched, and the results show that Cu foam can hardly change the kinetic parameters of Ga electrodeposition, but narrows the Tafel region due to its large surface area. The hydrogen evolution reaction promotes the mass transfer to the electrode, and the promotion effect of Cu foam is obviously better than that of Cu plate. The absolute value of mass transfer enhancement degree (exponent b ) of Cu plate and Cu foam is 0.39 and 1.12 respectively. The transformation of electrode surface structure at early stage can also affect Ga electrodeposition.