Hydrogen electrocatalysis

A selection of recent theoretical and experimental studies on electrolytic hydrogen evolution is presented. It is demonstrated with well-defined model surfaces that this reaction is a very structure-sensitive process. Crystallographic orientation, defect density and surface composition are parameters that determine the local geometric and electronic surface structure, and ore thus crucial for the electrocatalytic activity as characterised by the exchange current density. The observed trends can be understood within a recent theory by J.K. Norskov et al., which is based on density functional calculations and which emphasises the impact of hydrogen chemisorption energies on the reaction rate, that is, on the exchange current density. The particular electrocatolytic activities of ultrothin metal films and of nonostructures ore addressed.