Chemistry Department Colloquium

"Some Ways in which Surface Oxides Facilitate or Hinder Reactions"

Presented by Professor Talat Shahnaz-Rahman, University of Central Florida, Dept. of Physics

Wednesday, March 26, 2008, 11:00 am — Hamilton Seminar Room, Bldg. 555

It is conventional knowledge that metal surfaces are more reactive than those of their oxides. However, recent experimental results indicate that metal oxide surfaces may be quite reactive, leading to questions about the role of surface atoms and their vacancies in the reactions. Motivated by experimental results which show that the rate of CO oxidation on Cu2O surface is much higher than that on Cu and CuO surfaces [1], and that while RuO2(110) facilitates CO and NH3 oxidation, it does not do the same for NO [2], I will present results from first principles electronic structure calculations of the energetics of adsorption, diffusion, dissociation and oxidation of relevant molecules on corresponding oxide surfaces. Conclusions will be drawn about the characteristics of the surface electronic structure and local environment that may hinder or facilitate a particular reaction. Since reactions may leave oxygen vacancies in the surface, I will also address the question of healing of the surface. I will comment on the relevance of our result to recent observation of the reactivity of Cu2O nanoparticles[3] and of the oxide substrate in enhancing the reactivity of Au films [4]. In commenting on the relevance of our result to experimental observations I will present results also from kinetic Monte Carlo simulations with support from analysis of the local densities of electronic states and valence charge densities of the systems.
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1. T.-J. Huang and D.-H. Tsai, Catal. Lett. 87, 173 (2003).
2. S. Hong, TSR, K. Jacobi, G. Ertl, J.Phys. Chem.
3. B. White, M. Yin, A. Hall, D. Le, S. Stolbov, TSR, N. Turro, and S. O'Brien, Nano Letters 6, 2095 (2006).
4. M. S. Chen and D. W. Goodman, Surf. Sci. (2006).
* Work supported in part by DOE under Grant No. DE-FG02-07ER15842

Hosted by: James Muckerman

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