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

摘要

The rate of the hydrogen evolution reaction was studied at dropping indium amalgam electrodes (containing 0 to 65% indium) in 0.1 molar HC104 at 25C. The potential of zero charge was also determined for the same series of amalgams, and the Frumkin correction for the potential drop across the diffuse double layer was used to obtain the exchange current and transfer coefficient for each of the amalgams. The exchange current increases by approximately a factor of ten as the composition is varied from 0 to 65% In. The transfer coefficient is 0.50 independent of composition within experimental error. The current at the zero-charge potential, which gives a measure of the free energy of activation for the discharge reaction, increases by a factor of 10,000 as the composition is changed for 0 to 65% In. The corresponding decrease in the free energy of activation is approximately 5 kcal, and is attributed primarily to a change in work function. (Author)