Surface Science and Catalysis

Gabor Somorjai, Program Leader

The purpose of these programs is to carry out atomic and molecular level studies of surfaces that are important to existing and emerging technologies.  Three programs are described; LBNL divisions and  investigators are indicated.  The surface studies include metals and polymers.  Chemical properties are the focus of research.  The development of surface instrumentation (SFG, STM, AFM, LEED) for atomic characterization of surfaces is part of the program.

CURRENT PROGRAMS    (funded by DOE Basic Energy Sciences)
I. Chemical & Mechanical Properties of Surfaces, Interfaces & Nanostructures   (G. Somorjai)
Structure, chemical bonding and reactivity at buried interfaces of polymers and metals -  solid-liquid, solid-solid and solid-high pressure gas.

Monolayer films of cubic and hexagonal platinum and rhodium nanoparticles are being prepared and their surfaces studied by SFG spectroscopy and hi-pressure STM techniques under development, as were single crystal surfaces.    Also, the molecular-level interfacial structure of peptides adsorbed to hydrophobic and hydrophilic surfaces is under study by SFG, AFM and Quartz Crystal Microbalance, as well as by Molecular Dynamics simulations.

click figure to enlarge

II. Nanoscience and Nanoparticles for 100% Selective Catalytic Reactions
Synthesis, characterization and reactivity of three-dimensional high surface area nanoparticle systems to achieve 100% selective catalytic reactions.

  • Further development of highly controllable techniques for the synthesis of composed bimetallic and core-shell nanoparticles with maximal interface site density, and the study of their catalytic activity. (G. Somorjai)
  • Synthesis of metal nanoparticles a) within the cavities of >3rd generation dendrimers and b) supported on three-dimensional mesoporous oxides as well as industrially relevant alumina and zirconia materials, as potential highly selective catalysts. (G. Somorjai)
  • Continued development of X-ray techniques to determine electronic structure changes in nanoparticles and ligand molecules that correlate with reactivity and selectivity. (M. Salmeron) 

III. Strategic Design of Novel Catalysts for the Selective Synthesis of Fuels and Chemicals
Characterization and reactivity studies of two-dimensional arrays of metal nanoparticles for the strategic design of model catalysts.   (G. Somorjai)

  • Study of hydrogenation in organic solvent as a function of size and shape of the coated (protected) Pt nanoparticle catalyst.
  • Self-assembling anchorage of nonaggregated Pt nanoparticles to oxide films upon silicon wafers.  Characterization and study of selectivity;  extension to bimetallic nanocrystals
Figure: Pt nanoparticles of different sizes (transmission electron microscopy images at left) direct the course of cyclohexene hydrogenation/dehydrogenation differently (graph at right). Large particles favor hydrogenation to cyclohexane (blue), whereas small particles favor dehydrogenation to benzene (red). The y-axes indicate the fraction of each product in the mixture.