Hollow PdAg-CeO₂ heterodimer nanocrystals as highly structured heterogeneous catalysts

In the present work, hollow PdAg-CeO₂ heterodimer nanocrystals (NCs) were prepared and tested as catalysts for the selective hydrogenation of alkynes. These nanostructures combine for the first time the beneficial effect of alloying Pd with Ag in a single NC hollow domain with the formation of active sites at the interface with the CeO₂ counterpart in an additive manner. The PdAg-CeO₂ NCs display excellent alkene selectivity for aliphatic alkynes. For the specific case of hydrogenation of internal alkynes such as 4-octyne, very low over-hydrogenation and isomerization products were observed over a full conversion regime, even after prolonged reaction times. These catalytic properties were remarkably superior in comparison to standard catalysts. The promotion of Ag on the moderation of the reactivity of the Pd phase, in combination with the creation of interfacial sites with the CeO₂ moiety in the same nanostructure, is pointed as the responsible of such a remarkable catalytic performance.