Synthesis and properties of ternary noble metal oxide thin films

D. HOWARD; J.L. ENDRINO; A. ANDERS; F. CAPON; P. VERNOUX; L. LIZARRAGA; J.F. PIERSON

Garmisch-Partenkirchen

Conferencia; 20th International Conference on Plasma Surface Engineering; 2010

The chemistry of noble metal oxides is of great interest for achieving outstanding physical and chemical properties. Such compounds can usually hardly, or not at all, be synthesized by conventional chemistry routes. In contrast, the non-equilibrium condensation mechanisms associated with physical vapour deposition (PVD)processes widen the range of chemical, structural and morphological states that can be reached. The present talk illustrates how PVD processes open new possibilities for the synthesis of noble metals oxides and new opportunities in catalysis. The conditions to produce such chemical states, their thermal stabilities and some of their physical and chemical properties are explored through the investigation of three chemical systems: Pd-(Pt)-O, Na-Pt-O and Zr-Au-O. Pd-(Pt)-O particles derived from pulsed filtered cathodic arc deposited thin films have shown to exhibit a good and stable catalytic activity for the conversion of methane. This effect results from an improved resistance to the thermal reduction compared to Pd films oxidized during the catalytic analysis. Incorporating gold in zirconia allows the stabilisation of the Au-O bond at room temperature as shown by X-ray absorption near edge structure (XANES). The Au-O bond is partially reduced by annealing the samples in air and lead to the segregation of gold nanoparticles in the oxide matrix. Owing to the size of the gold particles, these films are promising for catalytic applications at room temperature. Finally, an original way to synthesize NaPt3O4 through thermal annealing and interaction with various substrates is described. A detailed XANES investigation is provided and some catalytic properties of the compound are described.