Charles T. Campbell

Professor of Chemistry, Lloyd E. and Florence M. West Endowed Professor of Chemistry
Co-Director, PNNL / UW Joint Institute for Nanotechnology
(Nanoscience, Physical, Bioanalytical, Environmental Catalysis, Ph.D., University of Texas at Austin, 1979)

(206) 616-6085
campbell@chem.washington.edu
Research Group Website

Research Interests

The Campbell research group pursues basic experimental research concerning environmental catalysis, Si / and polymer / metal interfaces, array-based biochemical analysis, nanomaterials and nanoelectronics fabrication. The main unifying themes of this broad-ranging work are: (1) development of tools that measure effects at surfaces more sensitively than anywhere else in the world, and (2) reactivity and physical chemistry of solid surfaces.

Environmental Catalysis

Chemical reactions catalyzed by solid surfaces dramatically improve the world in which we live. Still, the need for basic and applied research in catalysis is stronger than ever. Improving catalysts, for example, could minimize the use of fossil fuels, thus decreasing greenhouse gasses. Since there is a correlation between areas with high cancer death rates and those with high densities of pollution, an important approach to cancer reduction is the “greening” of industrial and automotive chemical processes to minimize pollution, again by modifying existing catalysts or inventing new ones. Improved catalysts do this either directly, by minimizing polluting side products, or indirectly, by minimizing requirements for feedstocks that themselves create pollution upon production. One goal of the Campbell research group is to clarify why catalyst modifiers act to promote catalytic activity or selectivity.

Transition metal catalysts are typically in the form of particles dispersed across the surface of some oxide support. Metal chemical reactivity can be tuned by varying the metal particle size. When the particles are only a few nanometers across, they can be much more active and selective in catalysis than larger particles. Unfortunately, such metal nanoparticles often sinter (i.e., combine with nearby particles and grow larger) under reaction conditions. The Campbell group is trying to improve environmental catalysts to resist sintering. For example, substantial NOx reduction could be realized if catalysts for the complete combustion of methane with low NOx emissions could be found. While Pd nanoparticles on alumina are excellent for this reaction, their resistance to sintering needs improvement before they realize this dream. Over 90% of the pollution from cars in the US comes out in the first 5 minutes after start-up, since the Pt and Pd catalysts in our catalytic converters do not work until they get very hot. Since supported Au nanoparticles can oxidize CO at room temperature, they might solve this so-called cold-start-up problem, but they suffer sintering problems. They study these systems with a wide array of experimental techniques. Theoretical calculations (DFT, kinetic Monte-Carlo, etc.) supply important complimentary energetic and dynamical insights.

Metal / Semiconductor and Metal / Polymer Interfaces

The Campbell group is the only group in the world that can measure the energetics of the surface reactions occurring during molecular beam epitaxy (MBE).  They are applying the unique calorimeter that does this, together with other surface characterization techniques, to study problems at metal / Si and metal / polymer interfaces that are of importance in making microelectronics, LEDs, solar cells, electro-optic modulators and opto-electric devices.

Array-based Biochemical Analysis

The Campbell group collaborates with biotechnologists to develop chips containing patterned microarrays of proteins which bind ligand and other protein, or DNAs whose sequences selectively bind proteins such as transcription factors, so that the chips serve as receptor arrays for sensitive, highly parallel detection of such proteins. Surface plasmon resonance (SPR) microscopy is being developed for probing large microarrays of biomolecules for their binding interactions with various partners and the kinetics of such binding.  It is possible to simultaneously monitor binding kinetics on >1300 spots within a protein microarray with a detection limit of ~0.3 ng per cm2, or <50 femtograms per spot (< 1 million protein molecules) with a time resolution of 1 s, and spot-to-spot reproducibility within a few percent.  Such instruments should be capable of high-throughput kinetic studies of the binding of small (~200 Da) ligands onto large protein microarrays.  The method is label free and uses orders of magnitude less of the precious biomolecules than standard SPR sensing.  It also gives the absolute bound amount and binding stoichiometry.

Nanomaterials

As the ability to produce nanomaterials such as nanodots and nanowires has advanced, it becomes more important to understand how the energy of the atoms in these materials is affected by their reduced dimensions. The Campbell group’s recently-invented single-crystal adsorption calorimeter, this country’s first, has proven powerful in this respect. Their calorimetric measurements reveal that metal energies vary with particle size much more strongly than predicted by the Gibbs-Thomson relation, taught in undergraduate Physical Chemistry textbooks. This has already been found to be crucial for accurate modeling of long-term sintering rates of metal nanoparticles in catalysts, but will no-doubt also prove important in understanding the rapidly-developing field of nanomaterials and nanoelectronics.

Nanoelectronics Fabrication

The Campbell group hopes to develop an interdisciplinary research team to synthesize and characterize novel 3-phase nanopatterned thin films, designed to favorably control the kinetics of self-assembly of nanoelectronics components. The nanostructures will be tailored using patterned nanoscale masks during vapor deposition. New methods will be developed to fabricate removable nano-patterned shadow masks that can be used for vapor deposition in ultrahigh vacuum, thus allowing a replica of the nanostructures on the mask to be written onto atomically-clean surfaces. These masks will be used to pattern 2-component surfaces, followed by self-assembly of a third component, to build 3-phase nanopatterned arrays of semiconductor heterostructures, interconnected quantum dot arrays, nanowires with end connects, semiconductor / insulator devices and well-defined model catalysts never before realized. Some of these structures will be applied to test the electron-transport properties of nanoelectronics components. The surface cleanliness of these nanostructures allow addressing several technologically important fundamental questions concerning the kinetics of nanoelectronic self assembly. They will study in detail the resulting tailored nanostructures, the novel masking techniques used to produce them, and key kinetic issues controlling nanoelectronics self-assembly using a combination of experimental probes (STM, AFM, XPS, LEIS, LEED).