Theoretical study of the adsorption and dissociation of oxygen on Pt(111) in the presence of homogeneous electric fields.
← Research streamUsing density functional theory (DFT), positive homogeneous electric fields reduced adsorption energies of oxygen species on Pt(111), while negative fields increased adsorption energies. The magnitude of the field-induced energy change depended primarily on t…
Study snapshot
Abstract
The effect of homogeneous electric fields on the adsorption energies of atomic and molecular oxygen and the dissociation activation energy of molecular oxygen on Pt(111) were studied by density functional theory (DFT). Positive electric fields, corresponding to positively charged surfaces, reduce the adsorption energies of the oxygen species on Pt(111), whereas negative fields increase the adsorption energies. The magnitude of the energy change for a given field is primarily determined by the static surface dipole moment induced by adsorption. On 10-atom Pt(111) clusters, the adsorption energy of atomic oxygen decreased by ca. 0.25 eV in the presence of a 0.51 V/A (0.01 au) electric field. This energy change, however, is heavily dependent on the number of atoms in the Pt(111) cluster, as the static dipole moment decreases with cluster size. Similar calculations with periodic slab models revealed a change in energy smaller by roughly an order of magnitude relative to the 10-atom cluster results. Calculations with adsorbed molecular oxygen and its transition state for dissociation showed similar behavior. Additionally, substrate relaxation in periodic slab models lowers the static dipole moment and, therefore, the effect of electric field on binding energy. The results presented in this paper indicate that the electrostatic effect of electric fields at fuel cell cathodes may be sufficiently large to influence the oxygen reduction reaction kinetics by increasing the activation energy for dissociation.
AI evidence extraction
Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.
Main findings
Using density functional theory (DFT), positive homogeneous electric fields reduced adsorption energies of oxygen species on Pt(111), while negative fields increased adsorption energies. The magnitude of the field-induced energy change depended primarily on the static surface dipole moment induced by adsorption and varied with model choice (10-atom clusters vs periodic slabs) and substrate relaxation; the authors suggest fields at fuel cell cathodes could influence oxygen reduction kinetics by increasing dissociation activation energy.
Outcomes measured
- Adsorption energies of atomic oxygen on Pt(111)
- Adsorption energies of molecular oxygen on Pt(111)
- Dissociation activation energy of molecular oxygen on Pt(111)
- Static surface dipole moment changes with cluster size and relaxation
Limitations
- The work is theoretical/computational (DFT) rather than experimental.
- Results depend on model representation (small Pt clusters vs periodic slab models).
- Field effects were sensitive to cluster size and substrate relaxation, affecting the static dipole moment and predicted energy changes.
View raw extracted JSON
{
"study_type": "in_vitro",
"exposure": {
"band": null,
"source": "homogeneous electric fields",
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"duration": null
},
"population": null,
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"outcomes": [
"Adsorption energies of atomic oxygen on Pt(111)",
"Adsorption energies of molecular oxygen on Pt(111)",
"Dissociation activation energy of molecular oxygen on Pt(111)",
"Static surface dipole moment changes with cluster size and relaxation"
],
"main_findings": "Using density functional theory (DFT), positive homogeneous electric fields reduced adsorption energies of oxygen species on Pt(111), while negative fields increased adsorption energies. The magnitude of the field-induced energy change depended primarily on the static surface dipole moment induced by adsorption and varied with model choice (10-atom clusters vs periodic slabs) and substrate relaxation; the authors suggest fields at fuel cell cathodes could influence oxygen reduction kinetics by increasing dissociation activation energy.",
"effect_direction": "mixed",
"limitations": [
"The work is theoretical/computational (DFT) rather than experimental.",
"Results depend on model representation (small Pt clusters vs periodic slab models).",
"Field effects were sensitive to cluster size and substrate relaxation, affecting the static dipole moment and predicted energy changes."
],
"evidence_strength": "insufficient",
"confidence": 0.74,
"peer_reviewed_likely": "yes",
"keywords": [
"density functional theory",
"homogeneous electric field",
"Pt(111)",
"oxygen adsorption",
"oxygen dissociation",
"activation energy",
"surface dipole moment",
"fuel cell cathode",
"oxygen reduction reaction"
],
"suggested_hubs": []
}AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.
Identifiers and source
DOI: 10.1021/jp045155y
PubMed: 16851701