Oxidation Catalysis by Gold Nano-Particles supported on h-BN Nanomesh

• Applicant: Professor Dr. Herbert Over
• Co-Applicant: Professor Dr. Peter Blaha
• Subject Area: Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: from 2009 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 131440158

Supported Au nano-particles are considered as promising oxidation catalysts with superior low temperature activity and selectivity in a variety of chemical reactions. However, supported nano Au-catalysts are facing a major problem with sintering under typical reaction conditions. For the case of Au/TiO2(110) oxygen vacancies or oxidized (alkaline) TiO2(110) may provide nucleation sites for immobilizing the Au clusters up to 500K. However, the microscopic processes responsible for the low temperature activity of Au particles on TiO2(110) are still controversially discussed in the literature. The recently discovered nanomesh of hexagonal BN (h-BN) on Rh(111) and on Ru(0001) offers a unique sturdy oxygen-free template for supporting Au nanoparticles. The h-BN/Ru(0001) nanomesh consists of a periodic hexagonal array of 2 nm wide pores with a lattice constant of 3.25 nm. The h-BN nanomesh can be viewed as a highly regular network of trapping sites in which deposited Au atoms preferentially condense into Au nano particles. This allows for the preparation of well-ordered model catalysts. With the Au/h-BN/Ru(0001) model catalyst we shall perform in-situ experiments and ab-initio calculations to elucidate both the oxidation behavior of Au particles and its catalytic behavior in oxidation reactions, including the simple CO oxidation and the “dream reaction” of propylene epoxidation. The oxygen-free h- BN nanomesh support facilitates significantly the identification of the catalytically active oxygen species on the Au particles with spectroscopic methods. The major goal of the present project is to advance the molecular understanding on the low-temperature activity of supported Au clusters which are not affected by defect sites of the supporting oxide surface. Electronic properties of the Au and oxidized Au clusters will be studied by photoemission spectroscopy and compared with first principles electronic structure calculations. The catalyzed oxidation reaction will be studied by in-situ infrared experiments/on-line mass spectrometry and modeled in detail by ab-initio calculations.

• DFG Programme: Research Grants
• International Connection: Austria