Epitaxial and Strong Support Interactions between Pt and LaFeO3 Films Stabilize Pt Dispersion.

The ability to stabilize very small Pt crystallites in supported-metal catalysts following harsh treatments is an important industrial problem. Here, we demonstrate that Pt particles can be maintained in the 1- to 2-nm range following multiple oxidation and reduction cycles at 1073 K when the particles are supported on 0.5-nm LaFeO3 films that have been deposited onto MgAl2O4 using atomic layer deposition. Characterization by scanning transmission electron microscopy suggests that when the catalyst is oxidized at 1073 K, the Pt crystallites are oriented with respect to the underlying LaFeO3. X-ray absorption spectroscopy also shows evidence of changes in the Pt environment. CO-oxidation rates for the reduced catalyst remain unchanged after five redox cycles at 1073 K. Epitaxial growth of Pt clusters and the consequent strong metal-support interaction between Pt and LaFeO3 are suggested to be the main reasons for the enhanced catalytic performances.