Electrochemistry of Fuel Cell Electrodes. Hydrogen Evolution at a Solid Indium Electrode

摘要

Measurements of hydrogen overvoltage on solid indium electrodes were made in 0.1 molar HClO4 at temperatures from 21C to 59.5C. The slow step in the hydrogen evolution reaction is probably discharge of a hydrogen ion, as indicated by the exchange current transfer coefficient (0.5), effect of added iodide ion, and effect of acid concentration. The enthalpy of activation is 14.1 = 0.5 KCal/mole at the reversible hydrogen potential and 10.0 = 0.2 KCal/mole at the zero-charge point. From these values, an estimate of 50 = 10 KCal/g atom is obtained for the heat of adsorption of hydrogen atoms on indium. The reaction is very sensitive to traces of oxygen, and the formation and removal of oxide films is discussed. (Author)