Effects of Oxygen Coverage and Hydrated Proton Model on the DFT Calculation of Oxygen Reduction Pathways on the Pt(111) Surface

Authors

Li-hui OU, College of Chemistry and Chemical Engineering, Hunan University of Arts and Science, Changde 415000, Hunan, China;College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China;
Sheng-li CHEN, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China;Follow

Corresponding Author

Sheng-li CHEN(slchen@whu.edu.cn)

Abstract

DFT calculation is used to study various possible steps in the oxygen reduction reaction (ORR), including the adsorption and dissociation process of O₂ and the serial protonation process of dissociated products to form H₂O on the Pt(111) surface. By using slabs of different sizes, and different numbers of pre-adsorbed oxygen atoms, the coverage effects on the pathways are investigated. The calculated results using different hydrated proton models are also compared. It is shown that the initial step of the ORR is the formation of a protonated end-on chemisorbed state of OOH*, which can transform to an unprotonated top-bridge-top state of O₂* or dissociate into adsorbed O* species with similar activation barrier. The calculated activation barriers for various possible steps at different oxygen coverages suggest that the protonation of O* to form OH* species is the rate-determining step in the ORR. With the increased oxygen coverage, the activation energy of this step decreases. It is found that the use of hydrated proton models more complicated than H₇O₃⁺ does not change the calculated pathways.

Graphical Abstract

Keywords

minimum energy path, ORR mechanism, oxygen coverage, hydrated proton model

DOI Link

https://doi.org/10.13208/j.electrochem.130894

Publication Date

2014-06-28

Online Available Date

2014-05-09

Revised Date

2014-05-02

Received Date

2014-03-19

Recommended Citation

Li-hui OU, Sheng-li CHEN. Effects of Oxygen Coverage and Hydrated Proton Model on the DFT Calculation of Oxygen Reduction Pathways on the Pt(111) Surface[J]. Journal of Electrochemistry, 2014 , 20(3): 206-218.
DOI: 10.13208/j.electrochem.130894
Available at: https://jelectrochem.xmu.edu.cn/journal/vol20/iss3/3