(52d) Interactions of Water and Chiral Properties of a Single Site Pt "29" Cuxo/Cu(111) Catalyst

Authors: 
Groden, K., Washington State University
Hensley, A., Washington State University
Therrien, A., Tufts University
Schilling, A. C., Tufts University
Zhang, R., Washington State University
Sykes, E. C. H., Tufts University
McEwen, J. S., Washington State University

Interactions
of Water and Chiral Properties of a Single Site Pt “29” CuxO/Cu(111)
Catalyst     

Kyle Groden, Alyssa
Hensley, Alex C. Schilling, Andrew Therrien, Renqin
Zhang, E. Charles H. Sykes, Jean-Sabin McEwen

Figure 1. Illustration of the excellent agreement between the simulated STM image of the “29” structural oxide model and the experimental STM image. The experimental and the simulated STM image were taken at -0.5 V. The images are 3.5× 3.5 nm2. The simulated image was done using the Tersoff-Hamann approach.

Single-site catalysts
provide a promising means of using precious catalytic metals to a high degree
of efficiency.  Their design greatly
reduces the metal loading and allows the atomically dispersed metal to actively
participate in the underlying reaction of interest.  Although the catalytic activity of single
atoms has been under scrutiny1, recent studies unambiguously show that individual Pt atoms on a “29”
copper oxide are able to oxidize CO
at low temperatures2.
The model system for the “29” copper oxide is shown in
Figure 1, which was obtained through an extensive collaboration between
experiment and theory3,4. To further investigate the activity of
this system, its interactions with water were examined from first principles.   This is in response to the experimental work,
which demonstrates that there is interchange of isotopically labelled surface
oxygen and that of gas phase water.  To
explain the experimental results, a reaction mechanism was proposed and a corresponding
microkinetic model was constructed to model the desorption kinetics.

We also examined the chiral
properties of the “29” copper oxide support used for the previously mentioned
work.  Imaging has determined 6 different
chiral configurations of the surface Cu2O rings, each of which may
behave in a chemically unique manner.  This
behavior may restrict the interactions of enantiomeric reactants to specific
surface configurations, potentially leading to heterogeneous selectivity.  As most reactions requiring any degree of
enantioselectivity are typically performed homogeneously, this possible
heterogeneous selectivity due to the surface orientation would be a powerful
characteristic of this catalytic system. 
Our investigation is performed again using density function theory with
propylene oxide as the enantiomeric probe molecule.

References:

1. Ding, K.; Gulec, A;
Johnson, A. M.;
Schweitzer, N. M.; Stucky, G. D.; Marks, L. D.
Stair, P. C. Science 2015, 350,
189–192.

2. Therrien, A.
J.; Hensley, A. J. R; Marcinkowski, M. D.; Lucci, F. R.; Coughlin, B.; Schilling, A.; McEwen, J.-S.;
Sykes, E. C. H.  (in preparation).

3. Hensley, A. J.
R.; Therrien, A. J.; Zhang, R.; Marcinkowski, M. D.; Lucci, F. R.; Sykes, E. C. H.; McEwen, J.-S. The Journal of Physical Chemistry C
2016, 120 (44), 25387–25394.

4. Therrien, A. J.;
Zhang, R.; Lucci, F. R.; Marcinkowski,
M. D.; Hensley, A.; McEwen, J.-S.; Sykes, E. C. H. The Journal of Physical Chemistry C
2016, 120 (20), 10879–10886.

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