Temperature dependence of hydrogen overvoltage on nickel and iron in acid solution

The temperature dependence of hydrogen overvoltage on mechanically and chem ically polished nickel electrodes, on iron armco, and iron of high purity i n 0.25 M H2SO4 are studied in the interval of temperatures 298-278 K. It is established that the influence of temperature on the slope of Tafel line d epends essentially on the type of electrodes. The apparent energy of activa tion E and pre-exponential factor B are determined. The results show an imp ortant role of the electrode surface treatment and purity of the metal in t he determination of energetic parameters of the hydrogen evolution reaction . The most striking result is that in the case of nickel electrodes with me chanically polished surface E increases and B decreases with the increase o f overvoltage. Some aspects of nonclassical behavior of electrodes studied are discussed.