Understanding how surface morphology and hydrogen dissolution influence ethylene hydrogenation on palladium

We prepared model supported nanoporous Pd catalysts grown via ballistic deposition with an unprecedented catalytic activity for ethylene hydrogenation. Extremely high conversion of ethylene to ethane (50%) exceeding that observed in prior studies by over an order-of-magnitude was achieved. Model Pd(111)/Pt(111) and Pd-decorated Pd(111)/Pt(111) and FeO(111)/Pt(111) thin film catalysts were employed to examine how the reactivity evolves with creation of catalytically active Pd sites. The origin of enhanced reactivity is shown to be due to the presence of highly reactive Pd sites and the absence of surface hydrogen depletion due to dissolution into the bulk. Collectively these studies present an enhanced and unified understanding of the catalytic behavior of various Pd samples employed in prior studies.