HYDROGEN DISSOCIATION ON AU-SUBSTITUTED PT CLUSTERS

London-Eyring-Polanyi-Sato (LEPS) method has been used to study the di ssociation of an H-2 molecule on Pt-18 and Pt17Au clusters. It has bee n found that on Pt-18 cluster, dissociation at bridge site is favoured ; the dissociated H atoms ultimately being chemisorbed on top sites. O n the Pt17Au cluster, on the other hand, dissociation at a top site is favoured when the dissociated species gets subsequently chemisorbed o n bridge sites. Relevance of the work in understanding the catalytic r eactions over alloy surfaces is discussed.