Lars Grabow, Ph.D. Assistant Professor of Chemical and Biomolecular Engineering grabow@uh.edu http://www.chee.uh.edu/faculty/grabow

 

The Computational Catalysis and Interface Chemistry group (CCIC), led by Assistant Professor Lars Grabow in the Department of Chemical and Biomolecular Engineering, uses computational methods to understand and predict chemical transformations that occur at solid-gas interfaces. In particular, Dr. Grabow’s work focuses on heterogeneously catalyzed reactions relevant for renewable energy production, energy storage, photocatalysis, pollution mitigation, and the production of useful chemicals. Density Functional Theory (DFT), kinetic modeling, and computational catalyst screening form the basic toolset to discover novel catalytic materials and aid experimental collaborators in understanding measured data and designing new experiments.

 

Active Sites at Metal/Metal-Oxide Interfaces 

 

Typical heterogeneous catalysts are composed of metal nanoparticles on metal-oxide supports, and the interface of both materials provides unique active sites for catalytic reactions. The electronic properties of supported metal nanoparticles depend strongly on the nature of the support, and these electronic properties ultimately govern the catalytic activity. Figure 1 visualizes the electron density changes of a 10-atom Ru nanoparticle upon adsorption to the (110) surface of TiO2. The cyan colored regions indicate electron depletion, while higher electron densities are present in the yellow regions. This information can be used to find preferred adsorption sites for important reactants, such as O2 or H2 for oxidation and reduction reactions, respectively.

 

Gold is known as a noble metal that does not react with oxygen. Yet, gold nanoparticles have the remarkable ability to catalyze the oxidation of carbon monoxide even below room temperature. After decades of fundamental research, this phenomenon is still not completely understood. However, using state-of-the-art computational methods, Dr. Grabow has demonstrated that water-promoted O2 activation at the interface of a 10-atom gold nanocluster on TiO2(110) is facile. Figure 2 illustrates how a co-adsorbed H2O molecule acts as proton shuttle and transfers an H atom from the oxide support to the adsorbed O2 intermediate. This weakens the O-O bond and allows for O2 dissociation even at low temperatures.

 

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Figure 1. Electron density difference plot for a 10-atom Ru nanocluster supported on TiO2 (110) (top view).

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Figure 2. Activation of O2 in the presenceof water at the metal/metal-oxide interface of a 10-atom Au nanocluster on TiO2(110) (side view).