ELECTROCHEMICAL STUDIES AT LOW-TEMPERATURES .2.

The effect of temperature and freezing of the solvent was studied on the rate of hydrogen evolution reaction on solid gallium electrode in aqueous solutions of HClO4, HCl and H2SO4 acids. We have found that in the solutions of these acids the cathodic current was increased as the temperature was lowered below freezing point, then at further lowering of temperature the current began to decrease. This phenomenon can be explained by assuming a competition between the normal decrease of current (rate) with temperature and an increase in rate of reaction due to the concentration of acid in liquid microphase. Beside these effects the change in the values of activation parameteres (E*, A') during the freezing of the solution has also to be taken into consideration. This may be due to the fact that the electrochemical reaction is simultaneously proceeding both at the Ga/liquid microphase and the Ga/ice-interface.