Stabilization and transformation of Pt nanocrystals supported on ZnAl2O4 spinel

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 a 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 microscopy and X-ray diffraction analyses 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 that the spinel support is a general mechanism for stabilizing precious metal catalysts, with important implications for the rational design of stable integrated catalysis systems.