THE PROCESSES OF FORMATION OF A GEL-LIKE ANODIC LAYER DURING POLARIZATION OF AN ANTIMONY ELECTRODE IN H2SO4 SOLUTION

During anodic polarization of antimony, the formation of a gel-like anodic layer has been observed. The voltammetric results and the shape of the impedance spectra during electrode polarization suggest that the anodic layer consists of two sublayers. It is assumed that an antimony basic sulphate gel-like layer is formed, denoted as Sb(OH)SO4. Sulphuric acid penetrates into the layer. The SO4(2-) diffusion flow is probably smaller than the flow of antimony ions formed by the electrochemical oxidation of antimony. Hence, alkalization of this second layer at the metal surface occurs and antimony hydroxide, denoted as SbOOH, is formed. Impedance measurements have shown that the rate of the electrochemical reaction is most probably determined by the transport of hydrogen ions in the SbOOH layer.