Epitaxial and Strong Support Interactions between Pt and LaFeO 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 LaFeO films that have been deposited onto MgAlO 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 LaFeO. 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 LaFeO are suggested to be the main reasons for the enhanced catalytic performances.