Correlations between electrochemical activity and heterogeneous catalysis for hydrogen dissociation on platinum

Hydrogen-deuterium exchange rates on platinum surfaces have been compared to equivalent hydrogen molecule and adsorbed hydrogen atom electrochemical oxidation rates on the same surfaces. Over a temperature range of 293 to 3600K the first order rate constants for H2-D2 exchange and hydrogen molecule electrochemical oxidation are the same, showing that the absorption-dissociation reaction (TAFEL, BONHOEFFER-FARKAS) is rate controlling. The rate of oxidation of the adsorbed hydrogen atom reaction involving electron transfer (VOLMER) is an order of magnitude larger. (auth.)