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Structure effects on electrocatalysts. Oxygen reduction on Te-modified Pt(111) surfaces: Site-blocking vs electronic
Ana María Gómez-Marín1, Valentín Briega-Martos2, Juan M Feliu2
1Department of Chemistry, Division of Fundamental Sciences (IEF), Technological Institute of Aeronautics (ITA), São José dos Campos CEP: 12228-900, SP, Brazil.
The Journal of Chemical Physics
|April 10, 2020
Summary
Tellurium adatoms on platinum surfaces initially hinder the oxygen reduction reaction (ORR). However, at higher coverages, activity improves, though still below clean platinum, suggesting complex catalytic effects.
Area of Science:
- Electrochemistry
- Surface Science
- Materials Science
Background:
- The oxygen reduction reaction (ORR) is crucial for fuel cell technology.
- Platinum (Pt) is a primary catalyst for ORR, but its efficiency and cost are limitations.
- Surface modification offers a route to enhance catalyst performance.
Purpose of the Study:
- To investigate the effect of tellurium (Te) adatoms on the ORR activity of Pt(111) surfaces.
- To elucidate the mechanisms behind Te modification on Pt(111) for ORR.
- To understand the role of Te coverage and electrolyte composition on catalytic performance.
Main Methods:
- Electrochemical studies of ORR on Te-modified Pt(111) in HClO4 and H2SO4.
- Kinetic current simulations using a mean-field model.
- Analysis of site blocking and electronic effects.
Main Results:
- Te adatoms initially decrease ORR onset and half-wave potentials in HClO4.
- ORR activity increases at higher Te coverages (>0.25) but remains lower than clean Pt(111).
- In H2SO4, Te adatoms exhibit a positive catalytic effect via competitive adsorption, replacing sulfate.
Conclusions:
- Te adatoms inhibit ORR in HClO4 primarily through electronic effects and site blocking of intermediates.
- A redox catalysis mechanism by Te adatoms is unlikely.
- In H2SO4, Te enhances ORR by displacing sulfate, indicating electrolyte-dependent mechanisms.
- Te modification does not inhibit the ORR despite blocking Hads and OHads adsorption, suggesting distinct active sites.
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