Comparison of reactivity on step and terrace sites of Pd (3Â 3Â 2) surface for the dissociative adsorption of hydrogen: A quantum chemical molecular dynamics study

► The exact nature of the active sites hence the mechanism by which they act, are still largely a matter of speculation. ► We have presented QCMD calculations for the interaction of H2 on different step and terrace sites of the Pd (3 3 2) surface. ► Saturated step sites can dissociate H2 moderately and that a monovacancy surface is suitable for significant dissociation. ► However in terrace site dissociation of H2 takes place only on Pd sites where the metal atom is not bound to any pre-adsorbed H atom. ► We identify a number of consequences for the interpretation and modeling of diffusion experiments demonstrating the coverage.