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RESEARCH PAPER

# $Pt3Cr(111)$ Alloy Effect on the Reversible Potential of OOH(ads) Formation from $O2(ads)$ relative to Pt(111)

[+] Author and Article Information
Jérôme Roques

Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106-7078

Alfred B. Anderson

Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106-7078aba@po.cwru.edu

J. Fuel Cell Sci. Technol 2(2), 86-93 (Nov 23, 2004) (8 pages) doi:10.1115/1.1867972 History: Received March 05, 2004; Revised November 23, 2004

## Abstract

A quantum mechanical study of $O2$ and OOH adsorption on Pt(111) and on a Pt monolayer on $Pt3Cr(111)$ is presented. The calculated adsorption energies are used to predict the reversible potential for $O2$ reduction to OOH(ads) on these surfaces. The resulting $0.43V$ for Pt(111) and $0.49V$ for the Pt skin on the $Pt3Cr(111)$ are far from the $1.23V$ reversible potential for the four-electron reduction to water. However, OOH(ads) easily dissociates over $Ptn$ sites $(n⩾2)$ to OH(ads) and O(ads), the latter forming with a reduction potential greater than $1.23V$ and the resulting heat loss contributes to the overpotential in the four-electron reduction process.

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## Figures

Figure 1

(a) Top view of the slab model used to study Pt3Cr(111) surface. The (2×2) unit cell used for the calculations is also represented by dashed lines. (b) Cross section view along the cut shown in (a).

Figure 2

O2 adsorption on Pt(111): (a) on bridge sites, and (b) on fcc sites or hcp sites. Large black circles are PT (first layer) and medium light circles are O atoms. For clarity, only the first layer is shown.

Figure 3

Representation of the seven high symmetry adsorption sites on the Pt skin on the Pt3Cr(111). Arrows define the (2×2) unit cell used for the calculations.

Figure 4

OOH adsorption on Pt(111): (a) on bridge sites, and (b) when the initial adsorption position is on fcc or hcp sites. Large black circles are Pt (first layer) and medium/small light circles are, respectively O∕H atoms. For clarity, only the first layer is shown.

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