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Title: The effect of co-adsorbed oxygen on the adsorption and diffusion of potassium on Rh(110): A first-principles study

Abstract

The adsorption and diffusion of potassium and oxygen on Rh(110), as well as the co-adsorption of K and O and its effect on K diffusion, has been studied using periodic density functional theory (DFT) calculations (PW91-GGA). On both the non-reconstructed (1x1) and the missing-row (MR) reconstructed surfaces, O prefers the short bridge site at low coverage, with a binding energy of ca. -5.2 eV at 1/4 ML. At theta_O>1/2 ML O atoms occupy alternating threefold sites along the ridge and forms a zigzag pattern. Interaction with the ridge sites is enhanced by the MR reconstruction. K prefers to be in the trough, with a binding energy of -2.3 eV on the (1x1) surface and -2.9 eV on the MR surface at 1/8 ML. Thus the adsorption of both O and K at low to medium coverage promotes the MR reconstruction. The co-adsorption of K and O enhances the binding energy of K to a maximum of -3.6 eV at the highest oxygen coverage studied, 1-3/8 ML. Oxygen adsorption is also stabilized by K, though to a smaller extent on a per-O atom basis. On both surfaces, K prefers to diffuse in the [110] direction with a barrier of ca. 0.05more » eV. O diffusion also prefers the [110] direction on the MR surface but is not clearly anisotropic on the (1x1) surface. The barrier to O diffusion ranges from 0.6~0.8 eV depending on the coverage and reconstruction. In the presence of co-adsorbed O, the diffusion barrier of K tops out at ca. 0.12 eV, much lower than earlier estimates based on mean-field models. Possible reasons for this apparent contradiction are discussed.« less

Authors:
 [1];  [2];  [2];  [3];  [4]
  1. ORNL
  2. Universitat Hannover, Germany
  3. Princeton University
  4. University of Wisconsin, Madison
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Center for Nanophase Materials Sciences
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
942233
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry C; Journal Volume: 111; Journal Issue: 20
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ADSORPTION; DIFFUSION; POTASSIUM; RHODIUM; SORPTIVE PROPERTIES; OXYGEN; DENSITY FUNCTIONAL METHOD; BINDING ENERGY

Citation Formats

Xu, Ye, Marbach, Hubertus, Imbihl, Ronald, Kevrekidis, Yannis G, and Mavrikakis, Manos. The effect of co-adsorbed oxygen on the adsorption and diffusion of potassium on Rh(110): A first-principles study. United States: N. p., 2007. Web. doi:10.1021/jp070654v.
Xu, Ye, Marbach, Hubertus, Imbihl, Ronald, Kevrekidis, Yannis G, & Mavrikakis, Manos. The effect of co-adsorbed oxygen on the adsorption and diffusion of potassium on Rh(110): A first-principles study. United States. doi:10.1021/jp070654v.
Xu, Ye, Marbach, Hubertus, Imbihl, Ronald, Kevrekidis, Yannis G, and Mavrikakis, Manos. Mon . "The effect of co-adsorbed oxygen on the adsorption and diffusion of potassium on Rh(110): A first-principles study". United States. doi:10.1021/jp070654v.
@article{osti_942233,
title = {The effect of co-adsorbed oxygen on the adsorption and diffusion of potassium on Rh(110): A first-principles study},
author = {Xu, Ye and Marbach, Hubertus and Imbihl, Ronald and Kevrekidis, Yannis G and Mavrikakis, Manos},
abstractNote = {The adsorption and diffusion of potassium and oxygen on Rh(110), as well as the co-adsorption of K and O and its effect on K diffusion, has been studied using periodic density functional theory (DFT) calculations (PW91-GGA). On both the non-reconstructed (1x1) and the missing-row (MR) reconstructed surfaces, O prefers the short bridge site at low coverage, with a binding energy of ca. -5.2 eV at 1/4 ML. At theta_O>1/2 ML O atoms occupy alternating threefold sites along the ridge and forms a zigzag pattern. Interaction with the ridge sites is enhanced by the MR reconstruction. K prefers to be in the trough, with a binding energy of -2.3 eV on the (1x1) surface and -2.9 eV on the MR surface at 1/8 ML. Thus the adsorption of both O and K at low to medium coverage promotes the MR reconstruction. The co-adsorption of K and O enhances the binding energy of K to a maximum of -3.6 eV at the highest oxygen coverage studied, 1-3/8 ML. Oxygen adsorption is also stabilized by K, though to a smaller extent on a per-O atom basis. On both surfaces, K prefers to diffuse in the [110] direction with a barrier of ca. 0.05 eV. O diffusion also prefers the [110] direction on the MR surface but is not clearly anisotropic on the (1x1) surface. The barrier to O diffusion ranges from 0.6~0.8 eV depending on the coverage and reconstruction. In the presence of co-adsorbed O, the diffusion barrier of K tops out at ca. 0.12 eV, much lower than earlier estimates based on mean-field models. Possible reasons for this apparent contradiction are discussed.},
doi = {10.1021/jp070654v},
journal = {Journal of Physical Chemistry C},
number = 20,
volume = 111,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}