SPM-based Methods for the Fundamental Understanding of Nano and Interfacial Catalysis
Our research focuses on molecular level studies of adsorption and catalytic reactions at surfaces and interfaces of nanocatalysts. To simulate the complexity of nanocatalysts, we use molecule beam epitaxy (MBE) and other modern synthesis techniques to prepare well-defined nanostructures as model systems; to investigate catalysts during operation, we utilize the full complement of modern surface science techniques and aim to develop in-situ microscopic techniques to study nanocatalysts from ultrahigh vacuum (UHV) to ambient pressures (AP). The model catalysts we investigated range from atomically clean nanostructures grown in UHV to impregnated nanocatalysts prepared by wet chemistry. The structure and surface chemistry of these well-defined model catalysts can be characterized by a series of surface techniques including scanning probe microscopies (STM and AFM), UV and X-ray photoemission spectroscopy (UPS and XPS) , ion scattering spectroscopy (ISS), temperature programmed desorption (TPD), high resolution electron energy loss spectroscopy (HREELS), infrared reflection absorption spectroscopy (IRAS), etc. In-situ studies of model nanocatalysts are carried out from watching the elementary steps to monitoring a working surface/interface, which provide unprecedented insights on the nature of active sites, as well as the reaction mechanism. To connect UHV surface science findings with real catalysis practice, our in-situ studies of model catalysts have spanned from vacuum conditions to ambient pressure reaction conditions, during which high pressure surface science techniques are used, such as AP-XPS and PM-IRAS. With these capabilities, we strive to achieve further understanding on confinement effect, a fundamental concept in catalysis, to build the relationship between surface structure and catalytic activity/selectivity at the electronic level, and on this basis to design highly efficient nanocatalysts.
Current Systems for In-Situ Surface Science Studies
Resolving the Active Sites:
Correlating Local Structures with Electronic Properties