Lay summary
Laysummary:For more than thirty years, single-crystal metal surfaces have served as model catalysts to permit surface characterization on the atomic and molecular level. The investigation of reactive surface intermediates and spectators would not have been possible with the discovery and development of SFG vibrational spectroscopy. However, industrial catalysis is mostly carried out on nanoparticles on high surface area oxides. Therefore, Prof. Somorjai has decided to focus SFG studies on these particles. The transition of SFG from single-crystal metal surfaces to nanoparticle catalysts is a key point of this post-doctoral project. This transition is challenging since obtaining an SFG signal from particles is difficult for several reasons. However, precursory studies on catalytic particle arrays, fabricated by electron beam lithography, were promising and demonstrated that SFG can be used for studying catalytic reactions. For the first time, SFG will be applied on synthesized Pt nanoparticles in order to investigate reaction intermediates and spectators. As a model catalytic reaction, ethylene hydrogenation at high pressures will be investigated and it is expected that reaction rates and selectivity are enhanced on the nanoparticle catalysts, compared to single-crystal metal surfaces. Kinetic analysis will be performed by analyzing reactants by gas chromatography (GC). The structure of the nanoparticle surfaces will further be investigated by scanning electron microscopy (SEM), high pressure scanning tunneling microscopy (STM) will give information on the mobility of metal atoms and organic intermediates and X-ray photoelectron spectroscopy (XPS) will be used to identify impurities on the reactive particle surfaces.