Professor and B. Seymour Rabinovitch Endowed Chair in Chemistry
Adjunct Professor of Chemical Engineering
Adjunct Professor of Physics
Ph.D. University of Texas at Austin, 1979
(Nanoscience, Environmental Catalysis, Physical, and Bioanalytical Chemistry)
The Campbell group pursues basic experimental research concerning energy-related and environmental catalysis. 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; 2) reactivity and physical chemistry at solid surfaces; and 3) kinetics and energetics of elementary steps in energy-related catalytic reactions on solid surfaces.
Energy-Related and 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 helping solve the energy crisis while decreasing greenhouse gases. Since there is a correlation between areas with high cancer mortality 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, and how nanoscale features of the catalyst surface can tuned to make better catalysts.
Transition metal catalysts are typically in the form of particles dispersed across the surface of some oxide or carbon 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 U.S. comes out in the first five 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. We study these systems with a wide array of experimental techniques. Theoretical calculations (DFT, kinetic modelling, etc.) supply important complimentary energetic and dynamical insights.
Thermodynamics and Kinetics of Nanomaterials for Energy Technologies
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 single-crystal adsorption calorimeter, this country’s first, has proven powerful in this respect, with calorimetric measurements revealing that metal energies vary with particle size much more strongly than predicted by the Gibbs-Thomson relation as 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.
Trends in Adhesion Energies of Metal Nanoparticles on Oxide Surfaces: Understanding Support Effects in Catalysis and Nanotechnology. Hemmingson. S. L. and Campbell, C. T. ACS Nano 2017, 11, 1196-1203.
Energetics of adsorbed formate and formic acid on Ni(111) by calorimetry. Zhao, W.; Carey, S. J.; Morgan, S. E.; Campbell. C. T. Journal of Catalysis 2017, 352, 300–304.
The Degree of Rate Control: A Powerful Tool for Catalysis Research. Campbell, C. T. ACS Catal. 2017, 7, 2770−2779.
Energetics of 2D and 3D Gold Nanoparticles on MgO(100): Influence of Particle Size and Defects on Gold Adsorption and Adhesion Energies. Hemmingson, S. L.; Feeley, G. M.; Miyake, N. J.; Cambell, C. T. ACS Catal. 2017, 7, 2151−2163.
Energetics of Adsorbed Methyl and Methyl Iodide on Ni(111) by Calorimetry: Comparison to Pt(111) and Implications for Catalysis. Carey, S. J.; Zhao, W.; Frehner, A.; Campbell, C. T. ACS Catal. 2017, 7, 1286−1294.
Equilibrium Constants and Rate Constants for Adsorbates: Two-Dimensional (2D) Ideal Gas, 2D Ideal Lattice Gas, and Ideal Hindered Translator Models. Campbell, C. T.; Sprowl, L. H.; Árnadóttir, L. J. Phys. Chem. C 2016, 120, 10283−10297.
Energies of Formation Reactions Measured for Adsorbates on Late Transition Metal Surfaces. Silbaugh, T. L.; Campbell, C. T. J. Phys. Chem. C 2016, 120, 25161−25172.
A benchmark database for adsorption bond energies to transition metal surfaces and comparison to selected DFT functionals. Wellendorff, J.; Silbaugh, T. L.; Garcia-Pintos, D.; Nørskov, J. K.; Bligaard, T.; Studt. F.; Campbell, C. T. Surface Science 2015, 640, 36–44.
Bond energies of molecular fragments to metal surfaces track their bond energies to H atoms. Karp, E. M.; Silbaugh, T. L.; Campbell, C. T. J. Am. Chem. Soc. 2014, 136, 4137−4140.
Introduction: Surface Chemistry of Oxides. Campbell, C. T.; Sauer, J. Chem. Rev. 2013, 113 (6), 3859–3862.
Energetics of Adsorbed CH3 and CH on Pt(111) by Calorimetry: Dissociative Adsorption of CH3I. Karp, E. M.; Silbaugh, T. L.; Campbell, C. T. J. Phys. Chem. C 2013, 117 (12), 6325–6336.