Research Interests
My primary research interests are in the fields of heterogeneous catalysis, surface science, materials science, and instrumentation development. Specifically, the preparation and evaluation of energy related materials. Some of my background and research interests include the capture and subsequent conversion of CO2 to useful chemical commodities (Figure 1), various catalytic reactions over metal-oxide supported nanoparticles, and the selective deoxyhydrogenation of biomass reforming products to fuels and other important chemicals. I also have a fascination with instrumentation development and have built and worked with several systems and techniques that allowed for materials and catalysts to be studied under a wide range of conditions that were previously inaccessible (Figure 3). The world class instrumentation available at the Department of Energy laboratories, particularly at the Center for Functional Nanomaterials and the National Synchrotron Light Source II located within Brookhaven National Laboratory, will be utilized to develop a complete understanding of the chemical systems of interest.
Studying model systems under ultrahigh vacuum (UHV) provides a pristine environment in which all aspects of a solid surface may be precisely tailored to meet the specific needs of a material. In addition, UHV conditions provide access to a wide suite of surface science characterization tools that rely on the use of electrons, ions, photons, tunneling, or chemical probes to study the surface, which would typically not be accessible under ambient conditions. Studying catalytically active materials under UHV removes the complexity and additional variables introduced by running the catalyst under more industrially relevant reaction conditions and simplifies the analysis so that a fundamental atomic scale level of understanding can be achieved and the specific active sites can be identified. This bottom-up approach of studying catalytically active materials allows us to intelligently design materials with improved performance and activity rather than a simple trial and error method that can be very costly and may have no guaranteed success due to the lack of understanding. I find the use of surface science tools and techniques as a very interesting and exciting way to improve our knowledge of how chemical systems and materials work down to the atomic level.
Figure 1: Carbon neutral fuel cycle. The waste product and greenhouse gas from the combustion process, CO2, is captured and through several chemical transformations is converted back into a suitable fuel that can be utilized in the combustion process again, thereby creating a carbon neutral fuel cycle.
I also have interests in more traditional ways of characterizing catalysts through the use of catalytic reactors and techniques that operate under ambient or near ambient conditions (Figure 3), which are more suitable to real world catalyst evaluation. While surface science provides valuable insight into the mechanism of solid-supported catalysts it falls short in establishing whether the catalyst's properties under UHV translate to more industrially relevant reaction conditions. Therefore, it is important to test and study the materials under actual reaction conditions at elevated temperatures and pressures inside chemical reactors. At BNL I plan on utilizing both surface science and chemical engineering methods to develop novel materials for use in a variety of fields that are of importance to society.
Figure 2: a) 110 x 110 nm scanning tunneling microscope (STM) image of 3-dimensional Au nanoparticles on rutile TiO2(110) and b) 70 x 70 Ă… STM image of a clean rutile TiO2(110) crystal. The color contrast represents the relative electron density around the individual atoms (brighter spots indicate higher electron density). In Figure 2b the bright spots indicate the location of individual titanium atoms present in the surface (green circle) while the dark areas indicate the location of oxygen atoms. Some oxygen atoms are missing and the underlying titanium atoms are observed as bright spots (blue circle) along the dark rows of oxygen atoms.
Figure 3: Photograph of the experimental setup on the ambient pressure X-ray photoelectron spectroscopy (AP-XPS) endstation at Brookhaven National Laboratory. The AP-XPS system is utilized to study model catalysts and materials under ambient conditions and down to pressures below 1 x 10-10 Torr.