GOALI: STM and AXAFS Studies of Electronic Effects due to Metal Support Interaction on Noble Metal Supported Catalysts

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This is a GOALI university-industry collabortive project. Prof. Wolf and Dr. Miller will measure the electronic properties of noble metal catalysts on various supports and verify whether changes in those properties are correlated with the observed changes by orders of magnitude in turnover frequency and selectivity. The model catalysts will consist of Pt and Pd deposited on thin films of metal oxide supports (alumina, silica, titania, and K-doped alumina, deposited or grown on Mo (110)). They will be compared with standard high surface are catalysts. The electronic structure of surfaces of surfaces will be probed with scanning tunneling spectroscopy (STS); its morphology with scanning microscopy (STM); and its reactivity with the kinetics of hydrogenolysis of neopentane and oxidation of methane. Metal particles will be synthesized with different sizes. STM will be used to ascertain the particle size distribution and STS will yield the electronics characteristics via I-V curves on the bare support and the particle-coated catalyst. Diffuse reflectance infrared spectroscopy (DRIFTS) of adsorbed CO will yield structural and electronic property information. The near neighbor structure of metals and support will be determined with EXAFS. The interatomic potential of Pt will be determined with atomic absorption x-ray spectroscopy (AXAFS) and correlated with catalysis and DRIFTS results. Acidity determinations will involve ammonia chemisorption. The STM work will be carried out at Notre Dame, while the EXAFS work by BP Amoco will require resources of the Argonne National Laboratory.