o-p H2 conversion on noble metals

Overview & Synopsis

Electron-energy-loss experiments of H2 physisorbed at low temperatures on a Ag(111) surface have indicated that the o-p H2 conversion rate is very fast , in contradiction with the usual belief that the catalyst must be magnetic to be efficient. We examine a large family of processes valid for non-magnetic and non-dissociative metals which physically convert the hydrogen molecules on the basis of the emission of metal electron-hole pairs. The importance of metal and molecule electron states in the processes is for the first time emphasized. The most efficient mechanism found is the Coulomb-Contact one based on a virtual charge transfer, back and forth, from the metal to the molecule, having a rate in agreement with experiment.