(479c) Surface Science of Metal Oxides – Insight into Structure-Activity Relationships through Studies of Single Crystals

Mark Barteau pioneered the use of single crystals as model catalysts in surface science studies of structure-activity relationships for metal oxides. In this talk I will first give an overview of some of the early work from Mark’s group on the reaction of alcohols and other oxygenates on single crystal surfaces of ZnO and TiO₂ which demonstrate both large crystal plane dependencies on reactivity and provide insight into the specific adsorption and reaction sites on these surfaces. I will then present results from similar studies from my group for reactions of oxygenates on single crystal surfaces of CeO₂ and ZrO₂. Finally, I will present some of our recent results on the interaction of Ni atoms with SrTiO₃ single crystal surfaces. In this work we have been exploring the dynamics of so-called “smart catalysts” in which supported metal particles are formed via the exsolution of metal cations from the bulk of the oxide. For Ni-doped SrTiO₃, exsolution produces metal particles that become socketed into the surface. This unique interfacial structure enhances the thermal stability and alters the reactivity of the metal particles. Our studies also show that the exsolution process is highly dependent on the crystallographic orientation of the oxide, with exsolution occurring only on certain surface planes. To provide insight into this process we have used AFM and TEM to study the ingress and egress of Ni atoms from the (111), (110), and (100) surfaces of SrTiO₃. The results of these experimental studies along with DFT calculations of the stability of surface and subsurface Ni atoms on each plane will be presented.