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We investigated the effect of surface atomic arrangements of electrodes on electrochemical oxidative desorption behavior of sulfur species at Pt single-crystal electrodes with face orientations of (111), (110), and (100) by electrochemical measurements, X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations. Upon the adsorption of elemental sulfur, electrochemical responses characteristic to Pt(111), Pt(110), and Pt(100) electrodes in aqueous electrolytes such as adsorption/desorption of hydrogen and hydroxyl species completely disappeared, and S 2p peaks attributed to the adsorbed sulfur appeared in XPS at each electrode. Those surface-structure-dependent electrochemical responses gradually recovered, simultaneously with the decrease of S 2p peaks, by cycling to or holding at positive potentials due to the oxidative desorption of adsorbed sulfur. The recovery of the electrochemically active surface area (ECSA) was promoted by keeping the potential more positive for a longer period. Among the three different face orientations, the oxidative desorption of sulfur started from the least positive potential at the Pt(111) electrode in both experiments, showing that the atomic arrangement of the Pt(111) electrode is most advantageous for the recovery of ECSA from sulfur poisoning. In the potential holding experiment, the oxidative desorption of sulfur occurred at less positive potential at the Pt(111), Pt(100), and Pt(110) electrodes in that order. One of the mechanistic reasons is explained with the DFT calculations, which evidenced that the adsorption energies of SO2 at the Pt(111), Pt(100), and Pt(110) electrodes are in the same order. This correlation suggests that the desorption of SO2 formed by the oxidation of the adsorbed sulfur is an important step.

Rights:

• Creative Commons BY-NC-ND Attribution-NonCommercial-NoDerivs 4.0 International
  

Keyword: Electrocatalysts, Fuel cells, Poisoning, Pt

Date published: 2024-10-03

Publisher: American Chemical Society (ACS)

Journal:

• The Journal of Physical Chemistry C (ISSN: 19327447) vol. 128 issue. 39 p. 16426-16436

Funding:

• New Energy and Industrial Technology Development Organization JPNP20003
• Japan Science and Technology Corporation JPMJGX23H0

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1021/acs.jpcc.4c03227

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Updated at: 2024-11-13 16:30:27 +0900

Published on MDR: 2024-11-13 16:30:27 +0900