| AVS 60th International Symposium and Exhibition | |
| Accelerating Materials Discovery for Global Competitiveness Focus Topic | Thursday Sessions |
| Session MG+MI+NS-ThM |
| Session: | Theoretical and Computational Methods |
| Presenter: | T.S. Rahman, University of Central Florida |
| Correspondent: | Click to Email |
An important ingredient in computational design of functional materials is back and forth feedback between theory and experiment, which necessarily involves modeling of realistic environments, using accurate methods. In this talk, I will present results of our density functional theory based calculations which together with experimental observations help isolate catalyst descriptors for specific reactions, in particular for supported nanoparticles. For example, for methanol oxidation on Au nanoparticles on titania [1], the higher activity of interfacial sites can be traced to charge-transfer-induced Coulomb interaction among the gold, reactant, and reducible TiO2 support, brought about through the formation of an ionic O−Au bond between gold and methoxy in such sites, which turns the participating perimeter gold atom cationic. A direct result of such charge-transfer-induced repulsive interaction between cationic gold and positively charged C moiety of methoxy is activation of the positively charged C moiety of methoxy, as manifested by the pronounced elongation of O−C bond length and the tilting of the methoxy axis, which facilitate reaction of methoxy through C−H scission with the bridge oxygen atoms that are readily available from the reducible support. I will use the above guidelines to predict the reactivity of several titania supported metallic/bimetallic nanoparticles for oxidation of organic molecules with the structure of R−O−R’, where R and R’are (saturated) hydrocarbons. Similarly, I will analyze the role of the interface (with the support) for a set of nanometer and sub-nanometer sized Pt nanoparticles on titania and alumina and point to the variations in the physical and chemical characteristics as a function of size, shape, and chemical environment (H and OH coverage). Through detailed comparison with XANES data [2], I will provide an understanding of the descriptors that control specific nanoparticle property.
[1] S. Hong and T. S. Rahman, J. Am. Chem. Soc., dx.doi.org/10.1021/ja4010738 (2013)
[2] F. Behafarid, L. K. Ono, S. Mostafa, J. R. Croy, G. Shafai, S. Hong, T. S. Rahman, Simon R. Bare and B. Roldan Cuenya, Phys. Chem. Chem. Phys., 2012, 14, 11766–11779
*Work supported in part by DOE under grant DE-FG02-07ER15842.