Williams Group

In Situ and Operando Vibrational Spectroscopic Studies of Heterogeneous Catalytic Interfaces

MELANIE SCHAAL

YARITZA LOPEZ

The Williams group research interests are in the area of heterogeneous catalysis and surface science, with a particular focus on studying solid-liquid catalytic interfaces.  Our primary research involves the development and application of in-situ or operando surface vibrational spectroscopic methods to study adsorption and catalysis at solid catalyst surfaces under industrially relevant reaction conditions (i.e., in the liquid phase and/or at high gas pressures and temperatures).  Specific techniques under development in our group include surface-enhanced Raman spectroscopy (SERS), attenuated total reflection infrared (ATR-IR) spectroscopy, and sum-frequency spectroscopy (SFS).  The information obtained with these approaches allows us to develop a molecular-level understanding of the catalytic mechanisms that govern the function of heterogeneous catalysts under reaction conditions.  Such understanding is critical if we wish to rationally design catalysts for specific applications in the future.  Reaction systems of interest in our group range from catalytic hydrogenations relevant to fine chemicals and pharmaceuticals production (e.g., enantioselective hydrogenation of α-ketoesters, hydrogenation of aliphatic nitriles) to fuel production and purification reactions (e.g., selective CO oxidation in the presence of H₂) required for implementation of proton exchange membrane (PEM) fuel cell technology.  Catalysts under investigation involve both polycrystalline transition metals and oxide-supported mono and bimetallic nanoparticle catalysts.  The latter materials are prepared either through traditional catalyst synthesis methods or more novel protocols that allow for control of size and composition on the nanoscale.  The Williams group is currently funded by the National Science Foundation, the USC Nanocenter, and by industry through the NSF I/UCRC for Fuel Cells.

Surface Enhanced Raman Spectrometer (SERS)

Automated Attenuated Total Reflection - IR Spectrometer (ATR-IR)

Sum Frequency Spectrometer pumped by a Nd:YAG Pulsed Laser Coupled with a OPG/OPA system

Dr. Christopher Williams

Dongxia Liu

Beau Waldrup

Melanie Schaal

Yaritza Lopez