# Fileset

[morooka-et-al-2024-potential-dependent-and-face-orientation-dependent-electrochemical-oxidative-desorption-behavior-of (1).pdf](https://mdr.nims.go.jp/filesets/1a880a7d-3658-46ff-9d07-a04f7f015b9d/download)

## Creator

[Tetsuro Morooka](https://orcid.org/0000-0003-3436-7030), Tamao Shishido, Ruttala Devivaraprasad, Ganesan Elumalai, Makoto Aoki, [Tetsuroh Shirasawa](https://orcid.org/0000-0001-5519-6977), [Takuya Nakanishi](https://orcid.org/0000-0002-1172-718X), [Atsushi Ishikawa](https://orcid.org/0000-0001-6908-831X), [Toshihiro Kondo](https://orcid.org/0000-0002-5235-7648), [Takuya Masuda](https://orcid.org/0000-0001-7462-2177)

## Rights

[Creative Commons BY-NC-ND Attribution-NonCommercial-NoDerivs 4.0 International](https://creativecommons.org/licenses/by-nc-nd/4.0/)

## Other metadata

[Potential-Dependent and Face Orientation-Dependent Electrochemical Oxidative Desorption Behavior of Sulfur Species Adsorbed on Platinum Single-Crystal Surfaces](https://mdr.nims.go.jp/datasets/b4d2b837-78dd-41b2-8fbd-aced869bce57)

## Fulltext

Potential-Dependent and Face Orientation-Dependent Electrochemical Oxidative Desorption Behavior of Sulfur Species Adsorbed on Platinum Single-Crystal SurfacesPotential-Dependent and Face Orientation-DependentElectrochemical Oxidative Desorption Behavior of Sulfur SpeciesAdsorbed on Platinum Single-Crystal SurfacesTetsuro Morooka, Tamao Shishido, Ruttala Devivaraprasad, Ganesan Elumalai, Makoto Aoki,Tetsuroh Shirasawa, Takuya Nakanishi, Atsushi Ishikawa, Toshihiro Kondo, and Takuya Masuda*Cite This: J. Phys. Chem. C 2024, 128, 16426−16436 Read OnlineACCESS Metrics & More Article Recommendations *sı Supporting InformationABSTRACT: We investigated the effect of surface atomic arrangements ofelectrodes on electrochemical oxidative desorption behavior of sulfur speciesat 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 theadsorption of elemental sulfur, electrochemical responses characteristic toPt(111), Pt(110), and Pt(100) electrodes in aqueous electrolytes such asadsorption/desorption of hydrogen and hydroxyl species completelydisappeared, and S 2p peaks attributed to the adsorbed sulfur appeared inXPS at each electrode. Those surface-structure-dependent electrochemicalresponses gradually recovered, simultaneously with the decrease of S 2ppeaks, by cycling to or holding at positive potentials due to the oxidativedesorption of adsorbed sulfur. The recovery of the electrochemically active surface area (ECSA) was promoted by keeping thepotential more positive for a longer period. Among the three different face orientations, the oxidative desorption of sulfur startedfrom 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 oxidativedesorption of sulfur occurred at less positive potential at the Pt(111), Pt(100), and Pt(110) electrodes in that order. One of themechanistic 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 oxidationof the adsorbed sulfur is an important step. In the potential cycling experiment, however, the oxidative desorption of sulfur moreeasily occurred at the Pt(111), Pt(110), and Pt(100) electrodes in that order. Once the adsorbed sulfur is oxidized to SO2, SO2desorbs from the surface or remains at the surface to be subsequently reduced to elemental sulfur in the negative potential scan.Since the reduction of SO2 to elemental sulfur more easily occurs at Pt(100) than at the other two electrodes, the recovery of ECSAat the Pt(100) electrode became slower in the potential cycling experiment. Thus, the fate of SO2 formed by the oxidation of sulfur isone of the important factors affecting the recovery rate of ECSA from sulfur poisoning.1. INTRODUCTIONPolymer electrolyte membrane fuel cells (PEMFCs) are apromising technology to convert chemical energy to electricalenergy with very high theoretical efficiency.1 In PEMFCs,supplied hydrogen is oxidized in the anode, while oxygen fromthe air is reduced in the cathode, and thesemultielectron transferreactions occur at the surface of the platinum (Pt) electro-catalyst.2,3 However, the cell performance of PEMFCs isseverely degraded by the adsorption of pollutants and impuritiespresent in air and hydrogen fuel gas.4 Because sulfur species suchas elemental S, H2S, C2S, COS, and SO2 strongly adsorb on thesurface of Pt electrocatalysts to suppress or rather enhance theelectrochemical processes,1,5−12 understanding and control ofadsorption/desorption behavior of sulfur species at Pt surfacesare especially important to sustain the inherent cell performanceof PEMFCs.In the 1980s and 1990s, the structures of sulfur adlayer withless than amonolayer (ML) coverage at Pt single-crystal surfaceshave been studied on an atomic scale from the fundamentalpoint of view.13−17 These studies determined well-orderedatomic arrangements of adsorbed sulfur, such as (√3 × √3)-R30° (0.3 ML) at the Pt(111),13,16,17 p(4 × 4) (0.8 ML) at thePt(110),14 and (√2 × √2)-R45° (0.5 ML) at the Pt(100)surfaces,13,15 by various surface characterization techniquesReceived: May 15, 2024Revised: August 9, 2024Accepted: September 5, 2024Published: September 19, 2024Articlepubs.acs.org/JPCC© 2024 The Authors. Published byAmerican Chemical Society16426https://doi.org/10.1021/acs.jpcc.4c03227J. Phys. Chem. C 2024, 128, 16426−16436This article is licensed under CC-BY-NC-ND 4.0Downloaded via NATL INST FOR MATLS SCIENCE (NIMS) on November 13, 2024 at 01:54:43 (UTC).See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Tetsuro+Morooka"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Tamao+Shishido"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Ruttala+Devivaraprasad"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Ganesan+Elumalai"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Makoto+Aoki"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Tetsuroh+Shirasawa"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Tetsuroh+Shirasawa"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Takuya+Nakanishi"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Atsushi+Ishikawa"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Toshihiro+Kondo"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Takuya+Masuda"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/showCitFormats?doi=10.1021/acs.jpcc.4c03227&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?goto=articleMetrics&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?goto=recommendations&?ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?goto=supporting-info&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=tgr1&ref=pdfhttps://pubs.acs.org/toc/jpccck/128/39?ref=pdfhttps://pubs.acs.org/toc/jpccck/128/39?ref=pdfhttps://pubs.acs.org/toc/jpccck/128/39?ref=pdfhttps://pubs.acs.org/toc/jpccck/128/39?ref=pdfpubs.acs.org/JPCC?ref=pdfhttps://pubs.acs.org?ref=pdfhttps://pubs.acs.org?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c03227?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://pubs.acs.org/JPCC?ref=pdfhttps://pubs.acs.org/JPCC?ref=pdfhttps://acsopenscience.org/researchers/open-access/https://creativecommons.org/licenses/by-nc-nd/4.0/https://creativecommons.org/licenses/by-nc-nd/4.0/https://creativecommons.org/licenses/by-nc-nd/4.0/https://creativecommons.org/licenses/by-nc-nd/4.0/https://creativecommons.org/licenses/by-nc-nd/4.0/including low-energy electron diffraction13,14 and scanningtunneling microscopy.15−17Afterward, the electro-oxidation behavior of sulfur at Ptsurfaces has been extensively studied by using Pt nanoparticlessupported on carbon electrodes, from a perspective of mitigationof sulfur poisoning in PEMFCs.8,9,18−23 However, the surfaces ofPt nanoparticles are mostly composed of (111) and (100) facetstogether with their steps/kinks/ledges under thermodynamicequilibria, and thus, averaged information for a variety ofreaction active sites can be obtained from electrochemical andspectroscopic analyses using Pt nanoparticles.Recently, to understand the site-dependent electro-oxidationmechanism of sulfur, a few groups have revisited thefundamental electrochemical properties of Pt single-crystalelectrodes with different face orientations in the presence ofsulfur species.13,24−27 The adsorption of sulfur on the Pt(111)surface caused the almost complete disappearance of character-istic current responses in sulfuric acid corresponding to theadsorption/desorption of hydrogen and hydroxyl species, whilethe oxidative desorption of sulfur by the electrochemicalpotential cycling in the range of −0.28 to +0.82 V vs Ag/AgClled to the recovery of those current responses.24,25 It should benoted that although the adsorbed structures of sulfur on each ofthe Pt(111), Pt(110), and Pt(100) single-crystal surfaces werefully determined on an atomic scale,13−17,24,25 their effects onthe oxidative desorption behavior are not fully understood.In the present work, we further systematically studied thepotential-dependent and face orientation-dependent adsorp-tion/desorption behavior of sulfur at the Pt(111), Pt(110), andPt(100) single-crystal electrodes by electrochemical measure-ments in perchloric acid, X-ray photoelectron spectroscopy(XPS), surface X-ray diffraction (SXRD), and density functionaltheory (DFT) calculations to explicitly clarify the oxidativedesorption mechanism about PEMFCs.2. METHODS2.1. Materials. The Pt(111), Pt(110), and Pt(100) single-crystal disks (99.99%, diameter:10 mm, thickness: 5 mm) werepurchased from the Surface Preparation Laboratory. Ultrapurereagent-grade HClO4 (60%) and reagent-grade Na2S (98.0%)were purchased from Wako Pure Chemicals, and first-grade 5%SO2 aqueous solution purchased from Sigma-Aldrich was usedwithout further purification. Water was purified using a Milli-Qsystem (ELGA LabWater). Ultrapure Ar (99.999%)/H2(99.999%) mixed gases (95:5) were purchased from SuzukiShokan.2.2. Sample Preparation. Prior to each measurement, thePt single-crystal electrodes were annealed using an inductionheater at 1600 °C for more than 1 h under the flowing Ar/H2mixed gas.28−31 After cooling under the flowing Ar/H2 mixedgas for 7 min, the clean Pt single-crystal electrodes wereimmersed in a 1 mM Na2S aqueous solution under the flowingAr/H2 mixed gas for 1 h to form S-adsorbed Pt single-crystalelectrodes. After being rinsed with water, those S-adsorbed Ptsingle-crystal electrodes were transferred to the electrochemicalcell filled with an S-free 0.1 M HClO4 aqueous electrolytesolution, with a droplet of water kept on the surface to avoid anysurface contamination.2.3. Electrochemical Measurements. Electrochemicalmeasurements were performed at room temperature by usinga three-electrode electrochemical cell in the hanging-meniscusconfiguration. An Ag/AgCl electrode (saturated NaCl, +0.200 Vvs RHE),32,33 Pt wire, and the Pt single-crystal electrodes wereused as a reference, counter, and working electrode, respectively.The potential of the working electrode was controlled by apotentiostat (HokutoDenko, HAB-151A). Potential-dependentcurrent responses were recorded by using a data logger(Graphtec, GL900). Cyclic voltammetry (CV) measurementsof the Pt single-crystal electrodes were carried out in an S-free0.1 M HClO4 aqueous electrolyte solution deaerated byultrapure Ar gas, unless otherwise specified. To clarify themechanism of oxidative desorption, the electrode potential wasregulated in two ways: (1) potential holding at “positivepotential limit” for 1 h followed by cycling to the less positivepotential and (2) potential cycling to the positive potential limit,for both of which the negative potential limit was set to −0.2 V(Figure 1).2.4. XPS Measurements. XPS measurements wereperformed using AXIS-NOVA (Shimadzu Kratos) equippedwith amonochromatic Al Kα source at an operating X-ray powerof 300 W without charge neutralization. The photoelectrontakeoff angle was fixed at 90°. The analysis area was a spot with adiameter of 110 μm, and the energy of the photoelectronspassing through the analyzer (pass energy) was 80 eV. Thevacuum pressure in the analysis chamber was ∼1.5 × 10−8 Torr.The position of the Pt 4f7/2 peak was calibrated to 71.2 eV, andthe intensity of the S 2p peak was normalized by dividing by thatof the Pt 4f peak of the same sample.2.5. SXRDMeasurements. The SXRDmeasurements werecarried out using a spectroelectrochemical cell as previouslyreported.31,34 The electrode potential was controlled with apotentiostat/galvanostat (Hokuto Denko, HA-151), and anFigure 1. Potential regulation for (A) potential holding and (B) potential cycling experiments (corresponding to the case where the positive potentiallimit is set to 1.0 V).The Journal of Physical Chemistry C pubs.acs.org/JPCC Articlehttps://doi.org/10.1021/acs.jpcc.4c03227J. Phys. Chem. C 2024, 128, 16426−1643616427https://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig1&ref=pdfpubs.acs.org/JPCC?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c03227?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asexternal potential was provided by a function generator (HokutoDenko, HB-111). A Pt wire and Ag/AgCl (saturated NaCl,+0.200 V vs RHE)32,33 electrode were used as a counter andreference electrode, respectively. The spectroelectrochemicalcell was set on a four-circle diffractometer (HUBER, type 5020)installed in an undulator beamline BL3A at the Photon Factory.The intensity of the incident X-rays was measured by an ionchamber, which was placed in front of the sample, to normalizethe intensity of diffracted X-rays. The incident X-ray energy of11.27 keV (wavelength: 1.10 Å) was selected to avoid anyfluorescence background from the Pt electrode. An energy-sensitive silicon drift detector was used to detect diffracted X-rays. For the SXRD measurements, hexagonal, square, andrectangular coordinate systems in which H and K are parallel tothe surface and L is normal to the surface were used at (111),(100), and (110) surfaces. The SXRD profiles were measured atL = 0.2 (incident angle: ca. 0.3−0.6°).2.6. Computational Details. The Pt(111), Pt(110), andPt(100) surfaces were constructed from the bulk Pt. The latticeconstants of the Pt bulk were optimized with the DFT. Thisprocedure gives the lattice constant of 3.92 Å, which is in goodagreement with the experimental value (3.91 A).35 For thelateral directions, a 3× 3 supercell was taken for Pt(111), while a2 × 2 supercell was taken for Pt(110) and Pt(100). Eight atomiclayers were taken for all surfaces. The number of Pt atoms was72, 32, and 32 for Pt(111), Pt(110), and Pt(100). For thesesurface models, the lower two atomic layers were fixed duringthe geometry optimization, and other layers were fixed to mimicthe bulk behavior. The adsorption site of SO2 is determinedaccording to the previous theoretical study.36In the DFT calculations, the core electrons were representedby the projector augmented-wave method,37 and the valenceelectrons were expanded by the plane wave basis set up to acutoff energy of 500 eV. Several exchange−correlation functionswere examined in this work: PBE,38 PBE-D3 with Becke−Johnson damping,38,39 vdw-DFT,40 BEEF-vdw,41 and opt-PBEfunctionals,42 as these functionals are relatively more accuratethan the standard generalized gradient approximation func-tionals. The optimization of bulk Pt was done with the PBEsolfunctional.43 The first-order Methfessel−Paxton scheme with σ= 0.01 was used for smearing the electron occupation near theFermi level. The convergence thresholds for the electronic statecalculation and geometry optimization were set to 1.0× 10−5 eVand 0.03 eV/Å in energy and force, respectively (in the bulk Ptoptimization, the convergence threshold of ion relaxation wasset to 1.0 × 10−6 eV in energy). Integration in the reciprocallattice space was performed by numerical integration using k-points, which were placed such that the spacing between themFigure 2. Cyclic voltammograms of (a) bare and S-adsorbed (A) Pt(111), (B) Pt(110), and (C) Pt(100) electrodes measured in a 0.1 M HClO4aqueous solution with a scan rate of 50 mV s−1 accompanied by preceding potential holding at (b) 0.5, (c) 0.7, (d) 0.8, (e) 0.9, and (f) 1.0 V for 1 h.Photoelectron spectra in the S 2p region of (a) bare and S-adsorbed (D) Pt(111), (E) Pt(110), and (F) Pt(100) electrodes obtained (a) before andafter the CV measurements accompanied by preceding potential holding at (b) 0.5, (c) 0.7, (d) 0.8, (e) 0.9, and (f) 1.0 V.The Journal of Physical Chemistry C pubs.acs.org/JPCC Articlehttps://doi.org/10.1021/acs.jpcc.4c03227J. Phys. Chem. C 2024, 128, 16426−1643616428https://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig2&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig2&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig2&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig2&ref=pdfpubs.acs.org/JPCC?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c03227?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-aswas 0.3 Å−1, while in the bulk Pt optimization, the spacing wasset to 0.1 Å−1. The gamma point was always included. For anisolated molecule, i.e., SO2 calculation, a single k-point wasplaced on the gamma point. A vacuum layer with a thickness of12 Å was placed between the slabs, and a dipole correction in thez-direction was introduced to remove the artificial interactionbetween the slabs. All the calculations were performed with theVienna ab initio simulation package (VASP) version 5.4.44,45The visualization of the molecular or surface structures wasmade with VESTA software.463. RESULTS AND DISCUSSION3.1. Electrochemical Properties of Bare and S-Adsorbed Pt Surfaces and Potential Holding Experi-ment. Figure 2A−C shows cyclic voltammograms of bare andS-adsorbed Pt(111), Pt(110), and Pt(100) electrodes in a 0.1 MHClO4 aqueous solution obtained after keeping the potential atthe various positive potential limits for 1 h. The cyclicvoltammogram of the bare Pt(111) electrode (Figure 2A(a),gray) showed characteristic current responses attributed toadsorption/desorption of hydrogen (−0.20 to +0.15 V, reaction1) and hydroxyl species (+0.30 to +0.60 V, reaction 2).29,47 Thecyclic voltammograms of bare Pt(110) (Figure 2B(a), gray) andPt(100) electrodes (Figure 2C(a), gray) were also identical tothose of the literature.29,47+ ++Pt H e Pt H (1)+ + ++Pt H O Pt OH H e2 (2)After the treatment with Na2S solution, those characteristiccurrent responses in cyclic voltammograms completely dis-appeared at each electrode (Figure 2A−C(b), red), indicatingthe blocking of adsorption/desorption of hydrogen andhydroxyl species due to the presence of adsorbed sulfur.Corresponding to these changes in cyclic voltammograms, adoublet peak assignable to the elemental sulfur adsorbed on Ptappeared at 162.4 and 163.6 eV in the S 2p region ofphotoelectron spectra for all of Pt(111), Pt(100), and Pt(110)electrodes (Figure 2D−F(a), red).48−50 The normalized peakintensity of adsorbed sulfur at the Pt(110) electrode (Figure2E(a), red) was somewhat larger than those at (nearly twiceFigure 3. Cyclic voltammograms of S-free bare (A) Pt(111), (B) Pt(110), and (C) Pt(100) electrodes measured in a 0.1 M HClO4 aqueous solution(a) without and (b) with 1 mM SO2 with a scan rate of 50 mV s−1. For the cyclic voltammograms measured in a 1 mM SO2-containing solution, 1st(black), 2nd (red), 5th (yellow), 10th (light green), 15th (green), 20th (blue), and 25th cycles (purple) were shown. Photoelectron spectra in the S 2pregion of (D) Pt(111), (E) Pt(110), and (F) Pt(100) electrodes obtained after (a) immersing in a 1 mMNa2S aqueous solution under the flowing Ar/H2 mixed gas for 1 h and (b) potential cycling in a 0.1MHClO4 aqueous solution containing 1mM SO2 with the positive potential limit of 0.7 V for 25times.The Journal of Physical Chemistry C pubs.acs.org/JPCC Articlehttps://doi.org/10.1021/acs.jpcc.4c03227J. Phys. Chem. C 2024, 128, 16426−1643616429https://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig3&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig3&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig3&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig3&ref=pdfpubs.acs.org/JPCC?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c03227?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asthose of) the Pt(111) (Figure 2D(a), red) and Pt(100)electrodes (Figure 2F(a), red). This is in reasonable agreementwith the coverages of sulfur, i.e., the ratios of the number ofsurface S and Pt atoms, 0.3ML at the Pt(111) electrode with the(√3 × √3)-R30° structure,13,16,17 0.8 ML at the Pt(110)electrode with the p(4 × 4) structure,14 and 0.5 ML at thePt(100) electrode with the (√2 × √2)-R45° structure,13,15 assummarized in Table S1 in the Supporting Information. It isnoted that the intensities and positions of S 2p peaks shown inFigure 2D−F were calibrated by those of Pt 4f peaks of the samesamples. In addition, the adsorbed structures of sulfur, (√3 ×√3)-R30° at the Pt(111) and (√2 × √2)-R45° at the Pt(100)electrodes, were evident by the SXRD peaks at (0 2/√3 0.2)and (0 1/√2 0.2) reciprocal lattice points, respectively, asshown in Figure S1 in the Supporting Information.+ + ++x x yS H O SO 2 H ex2 (3)+ + ++S 2H O SO 4H 4e2 2 (4)+ + ++S 4H O SO 8H 6e2 42(5)The potential holding at 0.5 V did not cause much change inthe cyclic voltammograms (Figure 2A−C(b), red) and photo-electron spectra of the S 2p region (Figure 2D−F(b)).When theholding potential became more positive, however, the oxidationcurrent started to flow at around 0.6 V at the Pt(111), Pt(110),and Pt(100) electrodes (the cyclic voltammograms shown inFigure 2A−C(d−f) are magnified in Figure S2A−C in theSupporting Information). These oxidation currents should bedue to the electrochemical oxidative desorption of adsorbedsulfur (reactions 3−5)23 because the intensities of S 2p peakssubstantially decreased after the potential holding at 0.7 V ormore positive (Figure 2D−F(c−f), yellow to black).The oxygen source for the oxidation of elemental sulfur isconsidered to be oxygen species adsorbed on the Pt surfaces,such as hydroxyl species and water molecules. The adsorbedamounts of oxygen species at “bare” Pt(111), Pt(110), andPt(100) single-crystal electrodes after electrochemical treat-ments at various electrode potentials were systematically studiedby electrochemical-XPS.51 The electrochemical-XPS showedthat, at all the face orientations, adsorbed OH and/or H2O wasdetected after the electrochemical treatment at 0.5 V vs RHE(∼0.3 V vs Ag/AgCl) or more positive. In the present study, thePt(111), Pt(110), and Pt(100) surfaces were covered by theadsorbed sulfur before the electrochemical measurements in(√3 × √3)-R30° with a coverage of 0.3 ML,13,16,17 p(4 × 4)with a coverage of 0.8 ML,14 and (√2 × √2)-R45° with acoverage of 0.5 ML,13,15 respectively. According to the adsorbedstructure of sulfur at each surface (Figure S1), however, there arestill sufficient vacant adsorption sites for oxygen species.Moreover, current waves (−0.1 to +0.3 V) attributable to thereduction of SO2 to elemental sulfur or sulfur interacting with Pt(see below in Figure 3, reaction 6)52 were clearly observed in thenegative going scan after the potential holding at 0.7 V (Figure2A−C(c), yellow), especially at the Pt(111) electrode (Figure2A(c), yellow).+ + ++SO 4H 4e S 2H O2 2 (6)These results show that the adsorbed sulfur is oxidized to SO2and/or SO42− at 0.7 V or more positive, and then some of thoseoxidized sulfur species desorb from the Pt surface and diffuseinto the bulk solution, while the remaining SO2 at the Pt surfaceis reduced to the adsorbed sulfur.After holding the potential at 0.7 V for 1 h, where theoxidation currents were barely observed at the S-adsorbedPt(111) electrode (Figure 2A(c), yellow and magnified inFigure S2A), the S 2p peaks almost disappeared at the Pt(111)electrode (Figure 2D(c)). When the positive potential limit, i.e.,holding potential, was extended to 0.9 V or more positive at thePt(111) electrode (Figure 2A(e,f), blue and black), a sharpoxidation peak was observed at around 0.84 V in the positivegoing scan, and a broad reduction peak of Pt oxide was observedat around 0.5 V in the negative going scan, as well as therecovered current waves due to the adsorption/desorption ofhydrogen and hydroxyl species. This confirms that the above-mentioned sharp peak is due to the oxidation of sulfur and the Ptelectrode, which brings about the recovery of the electrochemi-cally active surface area (ECSA). The difference between thecharge integration of the sharp sulfur oxidation peak at 0.84 V,423 μC cm−2, and that of the broad Pt oxide reduction peak at0.5 V, 58 μC cm−2, was in reasonable agreement with thetheoretical charge density of four-electron oxidation of sulfuradsorbed on the Pt(111) surface in the (√3 × √3)-R30°structure, 322 μC cm−2, implying that the major oxidationproduct is SO2 (reaction 4).The oxidative desorption of sulfur at the Pt(110) and Pt(100)electrodes occurred at a more positive potential than at thePt(111) electrode. After holding the potential of the S-adsorbedPt(110) electrode at 0.7 V, current wave due to the SO2reduction appeared in the CV (Figure 2B(c), yellow) and S2p peaks substantially decreased (Figure 2E(c)). In the case ofthe S-adsorbed Pt(100) electrode, the SO2 reduction currentand the decrease of S 2p peaks were barely observed afterholding the potential at 0.7 V [Figure 2C(c), yellow and Figure2F(c)] but more pronounced at 0.8 V [Figure 2C(d), green andFigure 2F(d)]. The oxidative desorption of sulfur at the Pt(110)and Pt(100) electrodes was almost completed by holding thepotential at 1.0 V [Figure 2E(f)] and 0.9 V [Figure 2F(e)] for 1h, respectively.It is noted that, after the potential holding at 0.9 V or morepositive [Figure 2A−C(e,f), blue and black], the shape ofcurrent waves due to the adsorption/desorption of hydrogenand hydroxyl species were substantially different from those oforiginal bare electrodes because the original surface atomicarrangements of the Pt(111), Pt(110), and Pt(100) electrodeswere severely compromised due to the oxidation and successivereduction.51,53−563.2. Electrochemical Reduction of SO2 to ElementalSulfur at Bare Pt Surfaces. Figure 3A−C shows cyclicvoltammograms of S-free bare Pt(111), Pt(110), and Pt(100)electrodes in a 0.1 MHClO4 aqueous solution containing 1 mMSO2, together with those without 1 mM SO2 for comparison. Atthe Pt(111) electrode, current waves attributed to the reductionof SO2 were certainly observed in the potential range of −0.1 to+0.3 V in the negative going scan of the first cycle (Figure 3A(b),black),52 together with hydrogen adsorption/desorption waves(−0.2 to +0.15 V). In the second cycle (Figure 3A(b), red), theSO2 reduction waves significantly decreased, while the hydrogenadsorption/desorption waves remained. Increasing the numberof potential cycling between −0.2 and +0.7 V (Figure 3A(b),yellow to purple), however, the hydrogen adsorption−desorption waves gradually decreased. Figure 3D−F shows theXPS results of the relevant specimens. After the potential cyclingfor 25 times, a doublet peak due to the adsorbed elementalsulfur, not oxidized sulfur species such as SO2, SO3, and SO42−,was observed in the S 2p region of the photoelectron spectrumThe Journal of Physical Chemistry C pubs.acs.org/JPCC Articlehttps://doi.org/10.1021/acs.jpcc.4c03227J. Phys. Chem. C 2024, 128, 16426−1643616430https://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.4c03227/suppl_file/jp4c03227_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.4c03227/suppl_file/jp4c03227_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.4c03227/suppl_file/jp4c03227_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.4c03227/suppl_file/jp4c03227_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.4c03227/suppl_file/jp4c03227_si_001.pdfpubs.acs.org/JPCC?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c03227?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as[Figure 3D(b)]. Although the SO2 reduction waves in cyclicvoltammograms at the Pt(110) [Figure 3B(b), black] andPt(100) electrodes [Figure 3C(b), black] were not as clear asthat at the Pt(111) electrode [Figure 3A(b), black], S 2p peaksoriginating from the adsorbed elemental sulfur were observed inthe photoelectron spectra of the Pt(110) [Figure 3E(b)] andPt(100) electrodes [Figure 3F(b)] after the potential cycling for25 times. These results confirm that some of the oxidativelyformed SO2 can be reduced to adsorbed sulfur in the negativegoing scan.At the Pt(111) [Figure 3D(b)] and Pt(110) electrodes[Figure 3E(b)], the intensities of S 2p peaks, i.e., the adsorbedamount of sulfur after the potential cycling in the SO2-containing solution, were somewhat smaller than those at thePt(111) [Figure 3D(a)] and Pt(110) electrodes [Figure 3E(a)]immersed in a 1 mM Na2S aqueous solution, respectively. Incontrast, the intensities of S 2p peaks at the Pt(100) electrodesafter immersion in a 1 mM Na2S aqueous solution [Figure3F(a)] and the potential cycling in the SO2-containing solution[Figure 3F(b)] were almost the same as each other. Theseresults suggest that the SO2 reduction and resulting readsorptionof sulfur are more likely to occur at the Pt(100) electrode than atthe Pt(111) and Pt(110) electrodes.3.3. Electrochemical Properties of Bare and S-Adsorbed Pt Surfaces and Potential Cycling Experiment.Figure 4 shows cyclic voltammograms of bare and S-adsorbedPt(111), Pt(110), and Pt(100) electrodes in a 0.1 M HClO4aqueous solution in the various potential ranges (A−C) with therelated XPS results (D−F). As is the case of the potential holdingexperiment (Figure 2), current responses characteristic to thebare Pt(111), Pt(110), and Pt(100) electrodes [Figure 4A−C(a), gray] completely disappeared after the adsorption of sulfur[Figure 4A−C(b), black], and a doublet peak corresponding tothe adsorbed sulfur appeared in the S 2p region of photoelectronspectra [Figure 4D−F(a)]. The potential cycling for 15 timeswith a positive potential limit of 0.7 V did not change the cyclicvoltammograms [Figure 4A−C(b), red to black] and photo-electron spectra of the S 2p region [Figure 4D−F(b)],confirming the blocking of adsorption/desorption of hydrogenand hydroxyl species by the adsorbed sulfur. It is noted that, inthe potential cycling experiment (Figure 4A−C), the oxidativedesorption of sulfur and recovery of electrochemical currentresponses occurred with more positive potential limits than inFigure 4. Cyclic voltammograms of (a) bare and S-adsorbed (A) Pt(111), (B) Pt(110), and (C) Pt(100) electrodes measured in a 0.1 M HClO4aqueous solution with a scan rate of 50mV s−1, with the positive potential limits of (b) 0.7, (c) 0.8, (d) 0.9, and (e) 1.0 V. For the cyclic voltammogramsof S-adsorbed Pt electrodes, 1st (red), 2nd (yellow), 5th (green), 10th (blue), and 15th cycles (black) were shown. Photoelectron spectra in the S 2pregion of (a) bare and S-adsorbed (D) Pt(111), (E) Pt(110), and (F) Pt(100) electrodes obtained (a) before and after the potential cycling with thepositive potential limit of (b) 0.7, (c) 0.8, (d) 0.9, and (e) 1.0 V for 14 times.The Journal of Physical Chemistry C pubs.acs.org/JPCC Articlehttps://doi.org/10.1021/acs.jpcc.4c03227J. Phys. Chem. C 2024, 128, 16426−1643616431https://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig4&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig4&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig4&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig4&ref=pdfpubs.acs.org/JPCC?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c03227?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asthe potential holding experiment (Figure 2A−C) because thepotential holding experiment kept the potential at the positivelimit for a longer period than the potential cycling experiment, asshown in Figure 1.After the potential cycling with the positive limit of 0.8 V for15 times [Figure 4A−C(c), red to black], the S 2p peaksdecreased significantly at the Pt(111) [Figure 4D(c)] andPt(110) electrodes [Figure 4E(c)] and slightly at the Pt(100)electrode [Figure 4F(c)]. Only at the Pt(111) electrode after thepotential cycling up to 0.8 V for 15 times, a new S 2p peakappeared at 166.7 eV [Figure 4D(c)], assignable to theoxidatively formed sulfur oxides such as SO2 and SO3, whichcan specifically adsorb on the Pt surfaces.57 As the positivepotential limit became 0.9 V or more positive, the currentresponses due to the adsorption/desorption of hydrogen andhydroxyl species gradually recovered with the number of cycles[Figure 4A−C(d,e), red to black]. Thus, the increase of thecurrent responses, i.e., recovery of ECSA, and decrease of the S2p peak intensity, i.e., desorption of sulfur, became morepronounced as the number of cycles increased and/or thepositive potential limit becamemore positive. After the potentialcycling up to 1.0 V for 15 times [Figure 4A−C(e), red to black],the increase of ECSA and changes in cyclic voltammogramsfrom those of original bare Pt(111), Pt(110), and Pt(100)electrodes due to the change in their atomic arrangement weremore significant than those of the potential holding experiment[Figure 2A−C(f), black]. Especially, a new reversible peakappeared at around −0.15 V at the Pt(111) electrode [Figure4A(e), black] due to the formation of the (110) substep.58−60These results show that the roughening of Pt surfaces wasaccelerated by repeating place-exchange of oxygen and Ptaccompanying oxidation/reduction cycles when the potentialwas swept up to the potential range where Pt oxide wasformed.61One may be concerned that the surface roughening affects theoxidative desorption of sulfur at the Pt surfaces because thecreated defect sites can alter the adsorption behavior of sulfurand oxygen species. This effect can be discussed by using thecyclic voltammograms of the Pt(111) electrode with the positivepotential limit of 1.0 V [Figure 4A(e)] as an example. Thecurrent peak due to the reduction of Pt oxide at 0.5 V was verysmall in the first potential cycling up to 1.0 V [Figure 4A(e),red], showing that the Pt oxide formation was rather suppressedby the adsorbed sulfur. In addition, the hydrogen adsorption/desorption current recovered up to ∼60% in the secondpotential cycling [Figure 4A(e), yellow] while maintaining thecharacteristic shape of hydrogen adsorption/desorption wavesat the Pt(111) electrode. Thus, the oxidative desorption of sulfuroccurs prior to the surface roughening caused by repeating thePt oxide formation and reduction. Furthermore, it was reportedthat S species rather preferentially adsorb on the flat terrace.62Figure 5. Recovery factor, RF, for (A) potential holding and (B) potential cycling experiments of the S-adsorbed Pt(111), Pt(110), and Pt(100)electrodes with respect to the positive potential limit.The Journal of Physical Chemistry C pubs.acs.org/JPCC Articlehttps://doi.org/10.1021/acs.jpcc.4c03227J. Phys. Chem. C 2024, 128, 16426−1643616432https://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig5&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig5&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig5&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig5&ref=pdfpubs.acs.org/JPCC?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c03227?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asAccordingly, the effect of surface roughening is considered to benot significant.3.4. Recovery from the Sulfur Poisoning and TheirFace Orientation Dependence at Pt Surfaces. Due to thesignificant importance of the oxidative desorption of sulfur fromPt(111), Pt(110), and Pt(100), which can be varied withdifferent electrochemical treatments (i.e., potential holding orcycling, positive potential limit), for the use of Pt electrodes inthe fuel cells, the recovery factor (RF) is defined as follows(equation 7) based on the electrochemical charge integrations ofhydrogen desorption at the Pt electrodes (Figure S3 in theSupporting Information).=CCRF XS adsorbed,bare (7)Here, CS‑adsorbed,X and Cbare are the charge integrations ofhydrogen desorption current at the S-adsorbed Pt electrodesafter the potential holding/cycling with the certain potentiallimit, X, and bare Pt electrodes with the corresponding faceorientation, respectively.RF was plotted with respect to the positive potential limit, asshown in Figure 5. Both the potential holding and cyclingexperiments show that, among the three different faceorientations, RF is highest at the Pt(111) electrode throughoutthe potential range of 0.8−1.0 V, showing that oxidativedesorption of sulfur and recovery of ECSA occur at less positivepotential than at the Pt(110) and Pt(100) electrodes.The RFs in Figure 5 show that the recovery from sulfurpoisoning is faster at Pt(111) than at Pt(110) and Pt(100)electrodes. To elucidate this difference, theoretical calculationsusing the DFT were carried out. It is known that the key speciesfor the sulfur oxidation at the Pt surface is SO2; for example, theDFT study by Yeh andHo has shown that the activation barriersfor S + O → SO and SO + O → SO2 are 0.44 and 0.41 eV,respectively.63 These values are much smaller than thedesorption energy of SO2, as will be shown later. In addition,the SO2molecule is experimentally observed in our work; thus, itshould be considered as the stable species during the sulfuroxidation on Pt surfaces. Considering this, the desorption of SO2from Pt surfaces can be assumed to be a thermodynamicalbottleneck. Based on the above assumption, the values ofadsorption energy (Ead) of SO2 were calculated with the DFT onPt(111), Pt(110), and Pt(100); the results are summarized inTable 1. The surface−adsorbate structures are shown in Figure6. The calculated values of Ead clearly show that the adsorptionof SO2 on Pt(111) is weaker than that at the other two surfaces;the values of Ead are −0.92, −1.41, and −1.35 eV on Pt(111),Pt(110), and Pt(100) (with the optPBE functional), respec-tively. Although the absolute values of Ead depend on theexchange−correlation functional, the SO2 adsorption strength isin the order of Pt(110) ≃ Pt(100) ≫ Pt(111) in all thefunctionals. The weakest SO2 adsorption on Pt(111) means thatthe desorption from the surface is favorable on Pt(111), whichhas been shown by an experimental RF value in Figure 5.Previously, the values of Ead of elemental sulfur on Pt(111),Pt(110), and Pt(100) surfaces were calculated to be −4.63,−4.37, and −5.16 eV, respectively.64 This order is incontradiction to the experimental observation that the RFvalue is highest at Pt(111), suggesting that the values of Ead ofelemental sulfur are unlikely to be the dominant factor.RFs of the Pt(110) and Pt(100) surfaces were almost identicalto each other but slightly higher at the Pt(100) surface in thepotential holding experiment, while their trend was opposite inthe potential cycling experiment. This contradiction should bedue to the SO2 reduction capability of the Pt(100) electrodebeing higher than those of the Pt(111) and Pt(110) electrodes,as discussed in Figure 3. According to the potential holdingexperiment (Figure 2), intrinsic sulfur oxidative desorptioncapabilities were higher at the Pt(111), Pt(100), and Pt(110)electrodes in that order, which is consistent with the adsorptionenergy of SO2. In the potential cycling experiment (Figure 4),however, some of the SO2 oxidatively formed during the positivegoing scan can be reduced to elemental sulfur (or sulfurinteracting with Pt) before further oxidation or diffusion in thebulk solution during the negative going scan. This cycle is morelikely to occur at the Pt(100) electrode than at the Pt(111) andPt(110) electrodes because of its higher SO2 reductioncapability (Figure 3), resulting in the slower recovery of ECSAat the Pt(100) electrode in the potential cycling experiment.4. CONCLUSIONSThe adsorbed sulfur significantly inhibits the electrochemicalresponses characteristic to each of the Pt(111), Pt(110), andPt(100) electrodes, originating from the surface-sensitiveprocesses such as adsorption/desorption of hydrogen andhydroxyl species. The ECSA, which is an important parameter inconsidering the use of Pt electrodes for fuel cells, graduallyrecovers by keeping the potential more positive for a longerperiod because of the oxidative desorption of sulfur species. Theadsorbed sulfur is oxidized mainly to SO2 at 0.7 V vs Ag/AgCl ormore positive. Then, some of the SO2 is further oxidized and/ordesorbs from the surface to diffuse into the bulk solution, whilethe remaining SO2 can be reverted to the reduced form, i.e.,elemental sulfur or sulfur interacting with Pt, at the surface in thenegative going scan. Among the elementary steps of theoxidative desorption process of adsorbed sulfur, the desorptionTable 1. DFT-Calculated Values of Adsorption Energy (Ead,in eV) of SO2 on the Pt(111), Pt(110), and Pt(100) SurfacesEstimated by Several Exchange−Correlation FunctionalsEad/eVsurface PBE PBE + D3 vdw-dft BEEF optPBE(111) −1.16 −1.81 −0.58 −1.04 −0.92(110) −1.64 −2.22 −1.09 −1.57 −1.41(100) −1.64 −2.22 −0.87 −1.36 −1.35Figure 6. Optimized structures (with the optPBE functional) of SO2molecules adsorbed on Pt(111), Pt(110), and Pt(100) (from left toright) surfaces. The top and bottom panels show the top and side views,respectively.The Journal of Physical Chemistry C pubs.acs.org/JPCC Articlehttps://doi.org/10.1021/acs.jpcc.4c03227J. Phys. Chem. C 2024, 128, 16426−1643616433https://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.4c03227/suppl_file/jp4c03227_si_001.pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig6&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig6&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig6&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?fig=fig6&ref=pdfpubs.acs.org/JPCC?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c03227?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asof SO2 from the surface is a very important one that significantlyaffects the overall rate of the process as well as the oxidationreaction of elemental sulfur and adsorption of oxygen species asan oxygen source. The atomic arrangement of the Pt(111)electrode that has the smallest adsorption energy of SO2 is themost advantageous for recovery from sulfur poisoning becausethe desorption of SO2 formed by the oxidation of elementalsulfur occurs more easily. This makes the recovery of ECSA at aless positive potential as compared to those of Pt(110) andPt(100) electrodes. Thus, the electrochemical oxidativedesorption of sulfur at Pt surfaces was studied using single-crystal electrodes to develop the mitigation materials/techniques against sulfur poisoning, and it was found that(111)-rich and (110)/(100)-poor Pt electrocatalysts can behighly tolerant to sulfur poisoning.■ ASSOCIATED CONTENT*sı Supporting InformationThe Supporting Information is available free of charge athttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227.Quantitative analysis based on XPS shown in Fig. 2D-F aand the theoretical number of atoms and coverage ofelemental sulfur at the S-adsorbed Pt(111), Pt(110), andPt(100) surfaces; SXRD measurements; magnified cyclicvoltammograms of Fig. 2 A-C for observing the onset ofsulfur oxidation current; and charge integrations ofhydrogen desorption current at the S-adsorbed Pt(111),Pt(110), and Pt(100) surfaces after the potential holding/cycling experiment, together with those of bare (PDF)■ AUTHOR INFORMATIONCorresponding AuthorTakuya Masuda − Research Center for Energy andEnvironmental Materials (GREEN), National Institute forMaterials Science (NIMS), Ibaraki 305-0044, Japan;orcid.org/0000-0001-7462-2177;Email: MASUDA.Takuya@nims.go.jpAuthorsTetsuro Morooka − Research Center for Energy andEnvironmental Materials (GREEN), National Institute forMaterials Science (NIMS), Ibaraki 305-0044, JapanTamao Shishido − Research Center for Energy andEnvironmental Materials (GREEN), National Institute forMaterials Science (NIMS), Ibaraki 305-0044, JapanRuttala Devivaraprasad − Research Center for Energy andEnvironmental Materials (GREEN), National Institute forMaterials Science (NIMS), Ibaraki 305-0044, JapanGanesan Elumalai − Research Center for Energy andEnvironmental Materials (GREEN), National Institute forMaterials Science (NIMS), Ibaraki 305-0044, JapanMakoto Aoki − Research Center for Energy and EnvironmentalMaterials (GREEN), National Institute for Materials Science(NIMS), Ibaraki 305-0044, JapanTetsuroh Shirasawa − Research Institute for Material andChemical Measurement, National Institute of AdvancedIndustrial Science and Technology (AIST), Ibaraki 305-8563,Japan; orcid.org/0000-0001-5519-6977Takuya Nakanishi − Research Center for Energy andEnvironmental Materials (GREEN), National Institute forMaterials Science (NIMS), Ibaraki 305-0044, Japan;orcid.org/0000-0002-1172-718XAtsushi Ishikawa − Department of Transdisciplinary Scienceand Engineering, School of Environment and Society, TokyoInstitute of Technology, Tokyo 152-8552, Japan;orcid.org/0000-0001-6908-831XToshihiro Kondo − Graduate School of Humanities andSciences, Ochanomizu University, Tokyo 112-8610, Japan;orcid.org/0000-0002-5235-7648Complete contact information is available at:https://pubs.acs.org/10.1021/acs.jpcc.4c03227NotesThe authors declare no competing financial interest.■ ACKNOWLEDGMENTSThis paper is based on results obtained from a project,JPNP20003, commissioned by the New Energy and IndustrialTechnology Development Organization (NEDO). This workwas also supported by GteX Program Japan grant numberJPMJGX23H0. Synchrotron radiation experiments wereperformed as projects approved by the High Energy AcceleratorResearch Organization (KEK) (proposal nos. 2016G588,2018G620, 2019G668, and 2020G671). We thank Dr. HironoriNakao for supporting SXRD measurements.■ REFERENCES(1) Borup, R.; Meyers, J.; Pivovar, B.; Kim, Y. S.; Mukundan, R.;Garland, N.; Myers, D.; Wilson, M.; Garzon, F.; Wood, D.; et al.Scientific Aspects of Polymer Electrolyte Fuel Cell Durability andDegradation. Chem. Rev. 2007, 107, 3904−3951.(2) Debe, M. K. Electrocatalyst approaches and challenges forautomotive fuel cells. Nature 2012, 486, 43−51.(3) Kodama, K.; Nagai, T.; Kuwaki, A.; Jinnouchi, R.; Morimoto, Y.Challenges in applying highly active Pt-based nanostructured catalystsfor oxygen reduction reactions to fuel cell vehicles. Nat. Nanotechnol.2021, 16, 140−147.(4) Garzon, F. H.; Lopes, T.; Rockward, T.; Sansiñena, J. M.; Kienitz,B.; Mukundan, R.; Springer, T. The Impact of Impurities On LongTerm PEMFC Performance. ECS Trans. 2009, 25 (1), 1575−1583.(5) Dong, W.; Xu, C.; Zhao, W.; Xin, M.; Xiang, Y.; Zheng, A.; Dou,M.; Ke, S.; Dong, J.; Qiu, L.; Xu, G. Poisoning Effects of H2S, CS2, andCOS on Hydrogen Oxidation Reaction over Pt/C Catalysts. ACS Appl.Energy Mater. 2022, 5, 12640−12650.(6) Reshetenko, T. V. Impacts of operating conditions on the recoveryof proton exchange membrane fuel cells exposed to sulfur dioxide in anair stream. J. Power Sources 2023, 559, 232676.(7) Mohtadi, R.; Lee, W.-K.; Cowan, S.; Van Zee, J. W.; Murthy, M.Effects of Hydrogen Sulfide on the Performance of a PEMFC.Electrochem. Solid-State Lett. 2003, 6 (12), A272−A274.(8) Ke, S.; Qiu, L.; Zhao, W.; Sun, C.; Cui, B.; Xu, G.; Dou, M.Understanding of Correlation between Electronic Properties and SulfurTolerance of Pt-Based Catalysts for Hydrogen Oxidation. ACS Appl.Mater. Interfaces 2022, 14, 7768−7778.(9) Mohtadi, R.; Lee, W.-K.; Van Zee, J. W. The effect of temperatureon the adsorption rate of hydrogen sulfide on Pt anodes in a PEMFC.Appl. Catal., B 2005, 56, 37−42.(10) Shi, W.; Yi, B.; Hou, M.; Jing, F.; Ming, P. Hydrogen sulfidepoisoning and recovery of PEMFC Pt-anodes. J. Power Sources 2007,165, 814−818.(11) Jerkiewicz, G.; Borodzinski, J. J.; Chrzanowskia, W.; Conway, B.E. Examination of factors influencing promotion of H absorption intometals by site-blocking elements. J. Electrochem. Soc. 1995, 142, 3755−3763.(12) Zolfaghari, A.; Jerkiewicz, G.; Chrzanowski, W.; Wieckowski, A.Energetics of the underpotential deposition of hydrogen on platinumelectrodes II. Presence of coadsorbed sulfur. J. Electrochem. Soc. 1999,146, 4158−4165.The Journal of Physical Chemistry C pubs.acs.org/JPCC Articlehttps://doi.org/10.1021/acs.jpcc.4c03227J. Phys. Chem. C 2024, 128, 16426−1643616434https://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?goto=supporting-infohttps://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.4c03227/suppl_file/jp4c03227_si_001.pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Takuya+Masuda"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://orcid.org/0000-0001-7462-2177https://orcid.org/0000-0001-7462-2177mailto:MASUDA.Takuya@nims.go.jphttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Tetsuro+Morooka"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Tamao+Shishido"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Ruttala+Devivaraprasad"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Ganesan+Elumalai"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Makoto+Aoki"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Tetsuroh+Shirasawa"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://orcid.org/0000-0001-5519-6977https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Takuya+Nakanishi"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://orcid.org/0000-0002-1172-718Xhttps://orcid.org/0000-0002-1172-718Xhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Atsushi+Ishikawa"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://orcid.org/0000-0001-6908-831Xhttps://orcid.org/0000-0001-6908-831Xhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Toshihiro+Kondo"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://orcid.org/0000-0002-5235-7648https://orcid.org/0000-0002-5235-7648https://pubs.acs.org/doi/10.1021/acs.jpcc.4c03227?ref=pdfhttps://doi.org/10.1021/cr050182l?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/cr050182l?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1038/nature11115https://doi.org/10.1038/nature11115https://doi.org/10.1038/s41565-020-00824-whttps://doi.org/10.1038/s41565-020-00824-whttps://doi.org/10.1149/1.3210713https://doi.org/10.1149/1.3210713https://doi.org/10.1021/acsaem.2c02284?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsaem.2c02284?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1016/j.jpowsour.2023.232676https://doi.org/10.1016/j.jpowsour.2023.232676https://doi.org/10.1016/j.jpowsour.2023.232676https://doi.org/10.1149/1.1621831https://doi.org/10.1021/acsami.1c18905?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.1c18905?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1016/j.apcatb.2004.08.012https://doi.org/10.1016/j.apcatb.2004.08.012https://doi.org/10.1016/j.jpowsour.2006.12.052https://doi.org/10.1016/j.jpowsour.2006.12.052https://doi.org/10.1149/1.2048409https://doi.org/10.1149/1.2048409https://doi.org/10.1149/1.1392607https://doi.org/10.1149/1.1392607pubs.acs.org/JPCC?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c03227?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as(13) Batina, N.; McCargar, J. W.; Salaita, G. N.; Lu, F.; Laguren-Davidson, L.; Lin, C.-H.; Hubbard, A. T. Structure and composition ofplatinum(111) and platinum(100) surfaces as a function of electrodepotential in aqueous sulfide solutions. Langmuir 1989, 5, 123−128.(14) Marcus, P.; Protopopoff, E. Coadsorption of sulphur andhydrogen on platinum (110) studied by radiotracer and electro-chemical techniques. Surf. Sci. 1985, 161, 533−552.(15) Maurice, V.; Marcus, P. STM imaging in air with atomicresolution of adsorbates on metal surfaces: Pt(100)-c(2 × 2)s. Surf. Sci.Lett. 1992, 262, L59−L64.(16) McIntyre, B. J.; Sautet, P.; Dunphy, J. C.; Salmeron, M.;Somorjai, G. A. Scanning tunneling microscopy tip-dependent imagecontrast of S/Pt(111) by controlled atom transfer. J. Vac. Sci. Technol. B1994, 12, 1751−1753.(17) Yoon, H. A.; Materer, N.; Salmeron, M.; Van Hove, M. A.;Somorjai, G. A. Coverage-dependent structures of sulfur on Pt(111)studied by low-energy electron diffraction (LEED) and scanningtunneling microscopy (STM). Surf. Sci. 1997, 376, 254−266.(18) Gould, B. D.; Baturina, O. A.; Swider-Lyons, K. E. Deactivationof Pt/VC proton exchange membrane fuel cell cathodes by SO2, H2Sand COS. J. Power Sources 2009, 188, 89−95.(19) Fu, J.; Hou, M.; Du, C.; Shao, Z.; Yi, B. Potential dependence ofsulfur dioxide poisoning and oxidation at the cathode of protonexchange membrane fuel cells. J. Power Sources 2009, 187, 32−38.(20) Ramaker, D. E.; Gatewood, D.; Korovina, A.; Garsany, Y.;Swider-Lyons, K. E. Resolving Sulfur Oxidation and Removal from Ptand Pt3Co Electrocatalysts Using in Situ X-ray Absorption Spectros-copy. J. Phys. Chem. C 2010, 114, 11886−11897.(21) Park, I.-S.; Xu, B.; Atienza, D. O.; Hofstead-Duffy, A. M.; Allison,T. C.; Tong, Y. J. Chemical State of Adsorbed Sulfur on PtNanoparticles. ChemPhysChem 2011, 12, 747−752.(22) Awad, M. I.; Saleh, M. M.; Ohsaka, T. Electroactivityregeneration of sulfur-poisoned platinum nanoparticle-modified glassycarbon electrode at low anodic potentials. J. Solid State Electrochem.2015, 19, 1331−1340.(23) Potgieter, M.; Parrondo, J.; Ramani, V. K.; Kriek, R. J. Evaluationof Polycrystalline Platinum and Rhodium Surfaces for the Electro-Oxidation of Aqueous Sulfur Dioxide. Electrocatalysis 2016, 7, 50−59.(24) Sung, Y.-E.; Chrzanowski, W.; Zolfaghari, A.; Jerkiewicz, G.;Wieckowski, A. Structure of Chemisorbed Sulfur on a Pt(111)Electrode. J. Am. Chem. Soc. 1997, 119, 194−200.(25) Sung, Y.-E.; Chrzanowski, W.; Wieckowski, A.; Zolfaghari, A.;Blais, S.; Jerkiewicz, G. Coverage evolution of sulfur on Pt(111)electrodes: From compressed overlayers to well-defined islands.Electrochim. Acta 1998, 44, 1019−1030.(26) Chen, C.-H.; Halford, A.; Walker, M.; Brennan, C.; Lai, S. C. S.;Fermin, D. J.; Unwin, P. R.; Rodriguez, P. Electrochemical character-ization and regeneration of sulfur poisoned Pt catalysts in aqueousmedia. J. Electroanal. Chem. 2018, 816, 138−148.(27) Kattwinkel, L.; Magnussen, O. M. Optical reflectance studies onthe oxidation of chemisorbed sulfur at the Pt(111) electrode.Electrochim. Acta 2022, 434, 141297.(28)Masuda, T.; Fukumitsu, H.; Kondo, T.; Naohara, H.; Tamura, K.;Sakata, O.; Uosaki, K. Structure of Pt(111)/Ionomer MembraneInterface and Its Bias-Induced Change in Membrane ElectrodeAssembly. J. Phys. Chem. C 2013, 117, 12168−12171.(29) Masuda, T.; Sonsudin, F.; Singh, P. R.; Naohara, H.; Uosaki, K.Potential-Dependent Adsorption and Desorption ofPerfluorosulfo-nated Ionomer on a Platinum Electrode SurfaceProbed by Electro-chemical Quartz Crystal Microbalance and AtomicForceMicroscopy. J.Phys. Chem. C 2013, 117, 15704−15709.(30) Clavilier, J. Flame-annealing and cleaning technique. Interfacialelectrochemistry: theory, experiment, and applications; Wieckowski, A.,Ed.; Marcel Dekker: New York, 1999; pp 231−248.(31) Kondo, T.; Tamura, K.; Takahashi, M.; Mizuki, J.; Uosaki, K. Anovel spectroelectrochemical cell for in situ surface X-ray scatteringmeasurements of single crystal disk electrodes. Electrochim. Acta 2002,47, 3075−3080.(32) Shatkay, A.; Lerman, A. Individual activities of sodium andchloride ions in aqueous solutions of sodium chloride. Anal. Chem.1969, 41, 514−517.(33) Rabie, H. R.; Wilczek-Vera, G.; Vera, J. H. Activities of individualions from infinite dilution to saturated solutions. J. Solution Chem. 1999,28, 885−913.(34) Masuda, T.; Uosaki, K. In situ determination of electronicstructure at solid/liquid interfaces. J. Electron Spectrosc. Relat. Phenom.2017, 221, 88−98.(35) Collard, S. M.; McLellan, R. B. High-temperature elasticconstants of platinum single crystals. Acta Metall. Mater. 1992, 40,699−702.(36) Ungerer, M. J.; Santos-Carballal, D.; Cadi-Essadek, A.; vanSittert, C. G. C. E.; de Leeuw, N. H. Interaction of SO2 with thePlatinum (001), (011), and (111) Surfaces: A DFT Study. Catalysts2020, 10, 558.(37) Blöchl, P. E. Projector augmented-wave method. Phys. Rev. B1994, 50, 17953−17979.(38) Perdew, J. P.; Burke, K.; Ernzerhof, M. Generalized GradientApproximation Made Simple. Phys. Rev. Lett. 1996, 77, 3865−3868.(39) Grimme, S.; Ehrlich, S.; Goerigk, L. Effect of the dampingfunction in dispersion corrected density functional theory. J. Comput.Chem. 2011, 32, 1456−1465.(40) Dion, M.; Rydberg, H.; Schröder, E.; Langreth, D. C.; Lundqvist,B. I. Phys. Rev. Lett. 2004, 92, 246401.(41) Wellendorff, J.; Lundgaard, K. T.; Møgelhøj, A.; Petzold, V.;Landis, D. D.; Nørskov, J. K.; Bligaard, T.; Jacobsen, K. W. Densityfunctionals for surface science: Exchange-correlation model develop-ment with Bayesian error estimation. Phys. Rev. B 2012, 85, 235149.(42) Klimes,̌ J.; Bowler, D. R.; Michaelides, A. Chemical accuracy forthe van derWaals density functional. J. Phys.: Condens. Matter 2010, 22,022201.(43) Perdew, J. P.; Ruzsinszky, A.; Csonka, G. I.; Vydrov, O. A.;Scuseria, G. E.; Constantin, L. A.; Zhou, X.; Burke, K. Restoring theDensity-Gradient Expansion for Exchange in Solids and Surfaces. Phys.Rev. Lett. 2008, 100, 136406.(44) Kresse, G.; Furthmüller, J. Efficient iterative schemes for ab initiototal-energy calculations using a plane-wave basis set. Phys. Rev. B 1996,54, 11169−11186.(45) Kresse, G.; Furthmüller, J. Efficiency of ab-initio total energycalculations for metals and semiconductors using a plane-wave basis set.Comput. Mater. Sci. 1996, 6, 15−50.(46) Momma, K.; Izumi, F. VESTA: a three-dimensional visualizationsystem for electronic and structural analysis. J. Appl. Crystallogr. 2008,41, 653−658.(47) Boronat-González, A.; Herrero, E.; Feliu, J. M. Determination ofthe potential of zero charge of Pt/CO electrodes using an impinging jetsystem. J. Solid State Electrochem. 2020, 24, 2871−2881.(48) Rodriguez, J. A.; Kuhn, M.; Hrbek, J. The bonding of sulfur to aPt(111) surface: photoemission and molecular orbital studies. Chem.Phys. Lett. 1996, 251, 13−19.(49) Yang, Z.; Wu, R.; Rodriguez, J. A. First-principles study of theadsorption of sulfur on Pt(111): S core-level shifts and the nature of thePt-S bond. Phys. Rev. B 2002, 65, 155409.(50) Rodriguez, J. A.; Dvorak, J.; Jirsak, T.; Liu, G.; Hrbek, J.; Aray, Y.;González, C. Coverage Effects and the Nature of theMetal-Sulfur Bondin S/Au(111): High-Resolution Photoemission and Density-Func-tional Studies. J. Am. Chem. Soc. 2003, 125, 276−285.(51) Wakisaka, M.; Udagawa, Y.; Suzuki, H.; Uchida, H.; Watanabe,M. Structural effects on the surface oxidation processes at Pt single-crystal electrodes studied by X-ray photoelectron spectroscopy. EnergyEnviron. Sci. 2011, 4, 1662−1666.(52) Quijada, C.; Vázquez, J. L.; Pérez, J. M.; Aldaz, A. Voltammetricbehaviour of irreversibly adsorbed SO2 on a Pt(111) electrode insulphuric acid medium. J. Electroanal. Chem. 1994, 372, 243−250.(53) Wakisaka, M.; Asizawa, S.; Uchida, H.; Watanabe, M. In situSTM observation of morphological changes of the Pt(111) electrodesurface during potential cycling in 10 mM HF solution. Phys. Chem.Chem. Phys. 2010, 12, 4184−4190.The Journal of Physical Chemistry C pubs.acs.org/JPCC Articlehttps://doi.org/10.1021/acs.jpcc.4c03227J. Phys. Chem. C 2024, 128, 16426−1643616435https://doi.org/10.1021/la00085a022?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/la00085a022?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/la00085a022?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1016/0039-6028(85)90826-Xhttps://doi.org/10.1016/0039-6028(85)90826-Xhttps://doi.org/10.1016/0039-6028(85)90826-Xhttps://doi.org/10.1016/0039-6028(92)90445-Chttps://doi.org/10.1016/0039-6028(92)90445-Chttps://doi.org/10.1116/1.587591https://doi.org/10.1116/1.587591https://doi.org/10.1016/S0039-6028(96)01405-7https://doi.org/10.1016/S0039-6028(96)01405-7https://doi.org/10.1016/S0039-6028(96)01405-7https://doi.org/10.1016/j.jpowsour.2008.11.072https://doi.org/10.1016/j.jpowsour.2008.11.072https://doi.org/10.1016/j.jpowsour.2008.11.072https://doi.org/10.1016/j.jpowsour.2008.10.103https://doi.org/10.1016/j.jpowsour.2008.10.103https://doi.org/10.1016/j.jpowsour.2008.10.103https://doi.org/10.1021/jp101977g?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp101977g?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp101977g?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1002/cphc.201000998https://doi.org/10.1002/cphc.201000998https://doi.org/10.1007/s10008-014-2470-7https://doi.org/10.1007/s10008-014-2470-7https://doi.org/10.1007/s10008-014-2470-7https://doi.org/10.1007/s12678-015-0283-9https://doi.org/10.1007/s12678-015-0283-9https://doi.org/10.1007/s12678-015-0283-9https://doi.org/10.1021/ja962637h?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/ja962637h?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1016/S0013-4686(98)00206-0https://doi.org/10.1016/S0013-4686(98)00206-0https://doi.org/10.1016/j.jelechem.2018.03.015https://doi.org/10.1016/j.jelechem.2018.03.015https://doi.org/10.1016/j.jelechem.2018.03.015https://doi.org/10.1016/j.electacta.2022.141297https://doi.org/10.1016/j.electacta.2022.141297https://doi.org/10.1021/jp402251z?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp402251z?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp402251z?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp404376t?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp404376t?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp404376t?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1016/S0013-4686(02)00226-8https://doi.org/10.1016/S0013-4686(02)00226-8https://doi.org/10.1016/S0013-4686(02)00226-8https://doi.org/10.1021/ac60272a006?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/ac60272a006?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1023/A:1021736315580https://doi.org/10.1023/A:1021736315580https://doi.org/10.1016/j.elspec.2017.03.012https://doi.org/10.1016/j.elspec.2017.03.012https://doi.org/10.1016/0956-7151(92)90011-3https://doi.org/10.1016/0956-7151(92)90011-3https://doi.org/10.3390/catal10050558https://doi.org/10.3390/catal10050558https://doi.org/10.1103/PhysRevB.50.17953https://doi.org/10.1103/PhysRevLett.77.3865https://doi.org/10.1103/PhysRevLett.77.3865https://doi.org/10.1002/jcc.21759https://doi.org/10.1002/jcc.21759https://doi.org/10.1103/PhysRevB.85.235149https://doi.org/10.1103/PhysRevB.85.235149https://doi.org/10.1103/PhysRevB.85.235149https://doi.org/10.1088/0953-8984/22/2/022201https://doi.org/10.1088/0953-8984/22/2/022201https://doi.org/10.1103/PhysRevLett.100.136406https://doi.org/10.1103/PhysRevLett.100.136406https://doi.org/10.1103/PhysRevB.54.11169https://doi.org/10.1103/PhysRevB.54.11169https://doi.org/10.1016/0927-0256(96)00008-0https://doi.org/10.1016/0927-0256(96)00008-0https://doi.org/10.1107/S0021889808012016https://doi.org/10.1107/S0021889808012016https://doi.org/10.1007/s10008-020-04654-7https://doi.org/10.1007/s10008-020-04654-7https://doi.org/10.1007/s10008-020-04654-7https://doi.org/10.1016/0009-2614(96)00066-8https://doi.org/10.1016/0009-2614(96)00066-8https://doi.org/10.1103/physrevb.65.155409https://doi.org/10.1103/physrevb.65.155409https://doi.org/10.1103/physrevb.65.155409https://doi.org/10.1021/ja021007e?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/ja021007e?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/ja021007e?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1039/c0ee00756khttps://doi.org/10.1039/c0ee00756khttps://doi.org/10.1016/0022-0728(93)03261-Mhttps://doi.org/10.1016/0022-0728(93)03261-Mhttps://doi.org/10.1016/0022-0728(93)03261-Mhttps://doi.org/10.1039/b923956ahttps://doi.org/10.1039/b923956ahttps://doi.org/10.1039/b923956apubs.acs.org/JPCC?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c03227?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as(54) Matsumoto, M.; Miyazaki, T.; Imai, H. Oxygen-EnhancedDissolution of Platinum in Acidic Electrochemical Environments. J.Phys. Chem. C 2011, 115, 11163−11169.(55) Conway, B. E.; Barnett, B.; Angerstein-Kozlowska, H.; Tilak, B.V. A surface-electrochemical basis for the direct logarithmic growth lawfor initial stages of extension of anodic oxide films formed at noblemetals. J. Chem. Phys. 1990, 93, 8361−8373.(56) Komanicky, V.; Chang, K. C.; Menzel, A.; Markovic, N. M.; You,H.; Wang, X.; Myers, D. Stability and Dissolution of Platinum Surfacesin Perchloric Acid. J. Electrochem. Soc. 2006, 153, B446−B451.(57) Streber, R.; Papp, C.; Lorenz, M. P. A.; Hofert, O.; Zhao, W.;Wickert, S.; Darlatt, E.; Bayer, A.; Denecke, R.; Steinrück, H. P.Influence of Steps on the Adsorption and Thermal Evolution of SO2 onClean and Oxygen Precovered Pt Surfaces. J. Phys. Chem. C 2010, 114,19734−19743.(58) Sonsudin, F.; Masuda, T.; Ikeda, K.; Naohara, H.; Uosaki, K.Effect of Coating by Perfluorosulfonated Ionomer Film on Electro-chemical Behaviors of Pt(111) Electrode in Acidic Solutions. Chem.Lett. 2010, 39, 286−287.(59) Itaya, K.; Sugawara, S.; Sashikata, K.; Furuya, N. In situ scanningtunneling microscopy of platinum (111) surface with the observation ofmonatomic steps. J. Vac. Sci. Technol., A 1990, 8, 515−519.(60) Sashikata, K.; Furuya, N.; Itaya, K. In situ electrochemicalscanning tunneling microscopy of single-crystal surfaces of Pt(111),Rh(111), and Pd(111) in aqueous sulfuric acid solution. J. Vac. Sci.Technol. B 1991, 9, 457−464.(61) Nagy, Z.; You, H. Applications of surface X-ray scattering toelectrochemistry problems. Electrochim. Acta 2002, 47, 3037−3055.(62) Herrero, E.; Climent, V.; Feliu, J. M. On the different adsorptionbehavior of bismuth, sulfur, selenium and tellurium on a Pt(775)stepped surface. Electrochem. Commun. 2000, 2, 636−640.(63) Yeh, C.-H.; Ho, J.-J. A First-Principle Calculation of SulfurOxidation on Metallic Ni(111) and Pt(111), and Bimetallic Ni@Pt(111) and Pt@Ni(111) Surfaces. ChemPhysChem 2012, 13, 3194−3203.(64) Bernard Rodriguez, C. R.; Santana, J. A. Adsorption and diffusionof sulfur on the (111), (100), (110), and (211) surfaces of FCCmetals:Density functional theory calculations. J. Chem. Phys. 2018, 149,204701.The Journal of Physical Chemistry C pubs.acs.org/JPCC Articlehttps://doi.org/10.1021/acs.jpcc.4c03227J. Phys. Chem. C 2024, 128, 16426−1643616436https://doi.org/10.1021/jp201959h?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp201959h?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1063/1.459319https://doi.org/10.1063/1.459319https://doi.org/10.1063/1.459319https://doi.org/10.1149/1.2229284https://doi.org/10.1149/1.2229284https://doi.org/10.1021/jp105994f?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp105994f?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1246/cl.2010.286https://doi.org/10.1246/cl.2010.286https://doi.org/10.1116/1.576378https://doi.org/10.1116/1.576378https://doi.org/10.1116/1.576378https://doi.org/10.1116/1.585589https://doi.org/10.1116/1.585589https://doi.org/10.1116/1.585589https://doi.org/10.1016/S0013-4686(02)00223-2https://doi.org/10.1016/S0013-4686(02)00223-2https://doi.org/10.1016/S1388-2481(00)00093-Xhttps://doi.org/10.1016/S1388-2481(00)00093-Xhttps://doi.org/10.1016/S1388-2481(00)00093-Xhttps://doi.org/10.1002/cphc.201200215https://doi.org/10.1002/cphc.201200215https://doi.org/10.1002/cphc.201200215https://doi.org/10.1063/1.5063464https://doi.org/10.1063/1.5063464https://doi.org/10.1063/1.5063464pubs.acs.org/JPCC?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c03227?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as