PNNL

Abstract

The role of interfacial interaction on the stabilization and transformation of Pt nanocrystals supported on zinc aluminate (ZnAl2O4) was systematically studied in this work. In addition to the remarkable stability of Pt nanocrystals supported on the {111} ZnAl2O4 facet under harsh oxidizing atmosphere, we also identified the phase segregation of ZnAl2O4 to ZnO and Al2O3 and the transformation of Pt to PtZn bimetallic alloy for Pt supported on other facets. High resolution scanning transmission electron microscope and X-ray diffraction analysis reveal the phase segregation is associated with a cation migration mechanism associated with replacement of Zn2+ by Al3+ in the spinel structure. This work confirms the strong interfacial interactions between precious metal nanocrystals and the spinel support is a general mechanism for stabilizing precious metal catalysts, and has important implication for the rational design of stable integrated catalysis systems