Chemistry Department Seminar

"Modeling of the synergistic behavior of adjacent Pt{111}"

Presented by Thobani Gambu, Catalysis Institute, Department of Chemical Engineering,, South Africa

Wednesday, June 14, 2017, 4:00 pm — Room 300 - Chemistry Bldg. 555

The oxygen reduction reaction (ORR) is particularly interesting, especially in the context of fuel cells and metal-air batteries [1,2]. The loss in cell potential at low current densities accounts for over 67% of the total potential loss and is primarily attributed to slow ORR kinetics [3]. When modelling the overall ORR activity over multifaceted Pt nanocrystallites, it is generally assumed that the different surface regions, i.e. terraces, edges and corners, are kinetically isolated and can therefore be modelled independently [4-5].

A range of ORR mechanisms have been proposed and the corresponding energetics, i.e. reaction and activation energies, have been calculated and reported [6-8]. A closer look at the reaction mechanisms and energetics shows that (1) O and OH removal over a Pt(111) and Pt(100) surface, respectively, is the most energetically hindered step, [6-8] and (2) facilitating an OH/O exchange between the Pt{111} and Pt{100} facets may result in improved ORR specific activity. Therefore, this study investigates the extent of O and OH cross-surface diffusion between the Pt{111} and Pt{100} facets of a pure Pt nanorod model. Furthermore, the cross-surface diffusion of OH on modified Pt nanorod models is reported.

1. Gewirth, A. A. and Thorum, M. S. Inorg. Chem. 49, 3557 (2010).
2. Nie, Y., Li, L. and Wei, Z. Chem. Soc. Rev. 44, 2168 (2015).
3. Gasteiger, H. A., Kocha, S. S. et al. Appl. Catal. B Environ. 56, 9 (2005).
4. Tripkovic, V., Cerri, I. et al. Catal. Letters. 144, 380 (2014).
5. Nesselberger, M., Ashton, S. et al. J. Am. Chem. Soc. 133, 17428 (2011). 6. Li, K., Li, Y. et al. J. Mater. Chem. A. 3, 11444 (2015).
7. Duan, Z. and Wang, G. J. Phys. Chem. C. 117, 6284 (2013).
8. Ford, D. C., Nilekar, A. U. et al. Surf. Sci. 604, 1565 (2010).

Hosted by: Miomir Vukmirovic

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