# Fileset

[electrochemical-oxidative-desorption-of-adsorbed-sulfur-species-on-(111)-surfaces-of-single-crystals-of-pure-pt-and-pt.pdf](https://mdr.nims.go.jp/filesets/0ed846f1-2543-47e2-806a-69334734d18e/download)

## Creator

Makoto Aoki, Tamao Shishido, [Tetsuro Morooka](https://orcid.org/0000-0003-3436-7030), [Takuya Nakanishi](https://orcid.org/0000-0002-1172-718X), [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

[Electrochemical Oxidative Desorption of Adsorbed Sulfur Species on (111) Surfaces of Single Crystals of Pure Pt and Pt-Based Bimetallic Alloys](https://mdr.nims.go.jp/datasets/ef3d972d-8cb8-4e07-8385-6b258955eebe)

## Fulltext

Electrochemical Oxidative Desorption of Adsorbed Sulfur Species on (111) Surfaces of Single Crystals of Pure Pt and Pt-Based Bimetallic AlloysElectrochemical Oxidative Desorption of Adsorbed Sulfur Species on(111) Surfaces of Single Crystals of Pure Pt and Pt-Based BimetallicAlloysMakoto Aoki, Tamao Shishido, Tetsuro Morooka, Takuya Nakanishi, and Takuya Masuda*Cite This: J. Phys. Chem. C 2025, 129, 2122−2131 Read OnlineACCESS Metrics & More Article Recommendations *sı Supporting InformationABSTRACT: The adsorption/desorption behavior of sulfurspecies at the (111) surfaces of pure Pt and various Pt-basedbimetallic alloys, denoted as Pt3M (M = Co, Cu, Fe, Pd), wasinvestigated by electrochemical measurements and X-ray photo-electron spectroscopy (XPS). After the adsorption of elementalsulfur, the current responses characteristic of the adsorption/desorption of hydrogen and hydroxyl species at the sulfur-free bare(111) surfaces completely disappeared, and a doublet peakcorresponding to the elemental sulfur appeared in the S 2p regionof XPS spectra. The characteristic current responses graduallyrecovered, simultaneously with the decrease of the S 2p peak, byrepeating the potential cycling between −0.2 and 0.8 V vs Ag/AgCl, indicating the oxidative desorption of S species. Except forthe Pt3Pd(111) surface, in which Pd has a similar atomic radius to Pt and fully occupied 4d orbitals, the Pt3M(111) surfaces showedhigher oxidative desorption capability than those of the pure Pt(111) surface; electrochemically active surface area recovered at thePt3M(111) surfaces by fewer potential cycles than at the Pt(111) surface. Among the various factors, the downshift of the d-bandcenter due to the ligand effect of foreign metal and the electronic interaction between adsorbed S and Pt are the dominant factorspromoting the oxidative desorption of sulfur as well as the strain effect of foreign metal with an atomic radius smaller than Pt.1. INTRODUCTIONPolymer electrolyte membrane fuel cells (PEMFCs) areattracting much attention as clean power sources fortransportation applications and residential power systems.1,2Sulfur (S) species, which exist in air in volcanic areas andhydrogen fuel gas, are one of the most severe pollutants forPEMFCs.3 They strongly adsorb on metal surfaces1,4 includingplatinum (Pt) surfaces that are most commonly usedelectrocatalysts in PEMFCs, resulting in the decrease ofelectrochemically active surface area (ECSA).1,3,5−7 Therefore,understanding the adsorption/desorption behavior of S speciesat the Pt-based electrocatalysts is very important to developingelectrocatalysts highly tolerant to S poisoning.The adsorption/desorption of S species at the Pt surface hasbeen extensively studied not only from a fundamentalviewpoint8−13 but also for practical applications inPEMFCs.5−7,14−21 In conjunction with the development ofClavilier’s method22 and advances in surface characterizationtechniques23 since the 1980s, the adsorbed structures of S onvarious Pt single crystal surfaces were determined on an atomicscale by low energy electron diffraction (LEED)8−11 andscanning tunneling microscopy (STM).11−13 Thereafter, theadsorption energy of S on the Pt surfaces was determined bydensity functional theory (DFT)4,24−26 based on theexperimentally determined atomic arrangement. These studiesshowed that the adsorption energy depends on the faceorientation of the Pt single crystal surfaces and adsorptionsites; for example, the adsorption energy of S is higher at the 4-fold hollow site, 3-fold hollow fcc site, hcp site, bridge site, andthe atop site in that order.4,24,26Recently, the oxidative desorption behavior of S species at Ptsingle crystal surfaces has been studied by various electro-chemical procedures for a fundamental understanding of Spoisoning in PEMFCs.10,20,27−30 Sung et al. revealed that thecurrent responses characteristic to the S-free bare Pt(111)single crystal surface were substantially blocked by theadsorbed S species, and then those recovered by repeatingthe electrochemical potential cycling in the range of −0.28 to0.82 V vs Ag/AgCl because of the oxidative desorption.10 Theyalso observed the current peak due to the oxidative desorptionof S species at 0.7 V vs Ag/AgCl in an aqueous solution ofReceived: October 1, 2024Revised: December 19, 2024Accepted: December 26, 2024Published: January 14, 2025Articlepubs.acs.org/JPCC© 2025 The Authors. Published byAmerican Chemical Society2122https://doi.org/10.1021/acs.jpcc.4c06652J. Phys. Chem. C 2025, 129, 2122−2131This article is licensed under CC-BY-NC-ND 4.0Downloaded via NATL INST FOR MATLS SCIENCE (NIMS) on December 15, 2025 at 04:01:32 (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="Makoto+Aoki"&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="Tetsuro+Morooka"&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="Takuya+Masuda"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/showCitFormats?doi=10.1021/acs.jpcc.4c06652&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?goto=articleMetrics&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?goto=recommendations&?ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?goto=supporting-info&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=tgr1&ref=pdfhttps://pubs.acs.org/toc/jpccck/129/4?ref=pdfhttps://pubs.acs.org/toc/jpccck/129/4?ref=pdfhttps://pubs.acs.org/toc/jpccck/129/4?ref=pdfhttps://pubs.acs.org/toc/jpccck/129/4?ref=pdfpubs.acs.org/JPCC?ref=pdfhttps://pubs.acs.org?ref=pdfhttps://pubs.acs.org?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c06652?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/sulfuric acid. On the other hand, Chen et al. observed thecurrent peaks due to the oxidative desorption of adsorbed Sspecies from the Pt(111) and Pt(100) surfaces at 1.43 and 1.36V vs RHE, respectively.20 They attributed this inconsistencyfrom the previous report by Sung et al.10 to the differentadsorption conditions such as the adsorption potential,concentration, and time. Recently, we further investigatedthe effect of potential and face orientation on the oxidativedesorption behavior of S species using Pt(111), Pt(100), andPt(110) single-crystal surfaces in an aqueous solution ofperchloric acid and revealed that the oxidative desorption of Sspecies occurs at the potential more negative at the Pt(111)surface than at the Pt(110) and Pt(100) surfaces in descendingorder of adsorption energy of SO2.31In addition to pure Pt, various Pt-based alloys (denoted asPt−M), such as Pt−Fe, Pt−Co, and Pt−Ni, have beenconsidered as electrocatalysts in PEMFCs because of theirhigher catalytic activity toward the oxygen reduction reaction(ORR),32−37 as well as their impact on cost reduction byreducing the amount of Pt.38 The origin of their improvedcatalytic activity for ORR was attributed to the shift of O2adsorption energy caused by the downshift of the d-bandcenter of the Pt alloying with foreign metal (M).39−45Afterward, the advantages of Pt−M alloys over pure Pt formitigating the S poisoning were suggested both theoret-ically46−49 and experimentally.16,47−49 Pillay et al.47 proposedthat the adsorption energies of S on the Pt3Ni(111)46 andPt3Co(111) surfaces47 were lower than those on the Pt(111)surface based on the DFT calculation. In addition, theyexperimentally demonstrated that the ECSA of the S-adsorbedPt3Co nanoparticles recovered by the oxidative desorptionafter the potential cycling between 0 and 1.03 V vs RHE for 5times, while that of the S-adsorbed Pt nanoparticles recoveredafter the same potential cycling for 30 times.47 Furthermore,Ke et al. reported that the loss of ECSA of the Pt−Co and Pt−Ru nanoparticles during the electrochemical treatments in asulfur-containing aqueous solution was less severe than that ofpure Pt nanoparticles.48,49 Those alloy nanoparticles alsoindicated the superior recovery capability from S poisoning tothe pure Pt nanoparticles during the potential cycling between0 and 1.4 V vs RHE probably due to the bifunctionalmechanism where CO oxidation was promoted by theadsorbed oxygen on Ru50 and/or ligand/strain effect ofcoexisting Co that causes the modulation of electronic stateof Pt.51 Thus, Pt−M alloys are fascinating electrocatalysts inPEMFCs because they can offer not only higher ORR activityand reduced Pt usage but also improved tolerance to Spoisoning.In the present study, we investigated the electrochemicaloxidative desorption behavior of S species at the single crystalsurfaces of pure Pt and Pt alloying with various foreign metalsby repeating the potential cycling between −0.2 and 0.8 V vsAg/AgCl. According to the discovery in our recent report thatPt(111) surface is most advantageous for recovery from Spoisoning among the Pt(111), Pt(110), and Pt(100)surfaces,31 (111) surfaces of pure Pt and Pt-based alloyswere used as working electrodes.2. METHODS2.1. Materials. The Pt(111) (10 mm in diameter and 5mm in thickness) and Pt-based bimetallic alloys denoted asPt3M(111) (8 mm in diameter and 2 mm in thickness, atomicratio of Pt:M = 3:1) single-crystal disks were purchased fromSurface Preparation Laboratory and Crystal Base Co., Ltd.,respectively. Super special grade HClO4 (60%) and wakospecial grade Na2S (98.0%) were purchased from Wako PureChemicals. Water was purified by using a Milli-Q system(ELGA LabWater, PURELAB flex3). Ultrapure Ar (99.9995%)and Ar/H2 mixed gases (95:5 v/v%, 99.999%) were purchasedfrom Suzuki Sho-kan.2.2. Electrochemical Measurements. The electrodepotential was controlled with a potentiostat (Hokuto Denko,HZ-7000). The electrochemical measurements were per-formed at room temperature using a three-electrode electro-chemical cell. A Pt wire and Ag/AgCl electrode (saturatedNaCl, +0.200 V vs RHE)31,52,53 were used as the counter andreference electrodes, respectively. Cyclic voltammetry (CV)measurements were carried out in an Ar-purged 0.1 M HClO4aqueous electrolyte solution with a scan rate of 50 mV s−1.Hereafter, the potential was expressed with respect to Ag/AgClunless otherwise specified throughout the paper.2.3. Sample Preparation. The Pt(111), Pt3Fe(111),Pt3Pd(111), Pt3Co(111), and Pt3Cu(111) single crystal diskswere annealed at 1600, 1400, 1200, 1000, and 1000 °C,respectively, for more than 1 h using an induction heater(Ambrell, EASYHEAT0224) under the flowing Ar/H2 mixedgas. After cooling under the flowing Ar/H2 mixed gas, thesurfaces of single crystal disks were brought in contact with anAr-purged 0.1 M HClO4 aqueous electrolyte solution withkeeping the potential at 0 V and CVs were measured to ensurethe cleanliness and atomic arrangement of the surfaces. Thiscycle is referred to as precycle in this paper. Then, the diskswere immersed in a 1 mM Na2S aqueous solution under theflowing Ar/H2 mixed gas for 1 h. After being rinsed with water,the surfaces of the disks were made in contact with a 0.1 MHClO4 aqueous electrolyte solution while keeping thepotential at 0 V, and then the electrode potential was cycledbetween −0.2 and 0.8 V 150 times to quantify the amount ofdesorbed S from the charge integrations of hydrogenadsorption/desorption waves.2.4. X-ray photoelectron spectroscopy measure-ments. X-ray photoelectron spectroscopy (XPS) measure-ments were carried out using an AXIS-NOVA (Shimadzu/Kratos). All the photoelectron spectra were obtained with amonochromatic Al Kα source (hν = 1486.6 eV) at 300 W. Theincident angle of the X-rays and the takeoff angle of thephotoelectrons were fixed at 35.5 and 90° to the electrodesurface, respectively. The pass energy of the electronspectrometer was 80 eV. XPS measurements of Pt(111) andPt3M(111) surfaces were performed after induction heating,after immersing in a 1 mM Na2S aqueous solution, and afterelectrochemical potential cycling in a 0.1 M HClO4 aqueouselectrolyte solution for 15 and 150 times. The samples, exceptfor those after induction heating, were rinsed with water,followed by blowing off the remaining water with air. Then, allof the samples were transferred into the analysis chamber ofXPS. The sample transfer was carried out in air and completedin a few minutes. One may be concerned with possible sidereactions such as surface oxidation during the sample transfer,but no significant spectral changes were observed in multipleexperiments. The intensities of Pt 4f peaks were normalized,and the intensities of S 2p peaks were divided by the integratedintensities of corresponding Pt 4f peaks. Binding energies werecalibrated by referencing C 1s peaks that can be assigned to thehydrocarbon contamination (285.0 eV).The Journal of Physical Chemistry C pubs.acs.org/JPCC Articlehttps://doi.org/10.1021/acs.jpcc.4c06652J. Phys. Chem. C 2025, 129, 2122−21312123pubs.acs.org/JPCC?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c06652?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as3. RESULTS AND DISCUSSION3.1. Pt(111). Figure 1A shows cyclic voltammograms(CVs) of bare and S-adsorbed Pt(111) single crystal electrodesmeasured in an Ar-purged 0.1 M HClO4 aqueous electrolytesolution with a scan rate of 50 mV s−1. The CV of barePt(111) electrode (Figure 1A(a)) shows characteristic currentresponses such as adsorption/desorption of hydrogen (−0.20to 0.15 V) and hydroxyl species (0.30 to 0.60 V with a peak at0.54 V).54After immersing the Pt(111) electrode in a 1 mM Na2Saqueous solution, those characteristic current responsesdisappeared (blue line in Figure 1A(b)) and doublet peakscorresponding to adsorbed elemental S (163.1 eV20,55,56), aswell as indistinct peaks due to SO2 (165.7 eV20,55,56) andSO42− (168.0 eV20,48,55,56), appeared in the S 2p region ofphotoelectron spectra (Figure 2A(b)). This suggests that theadsorption/desorption of hydrogen and hydroxyl species wasblocked by adsorbed elemental S on the Pt(111) surface. Asthe number of potential cycles increased, those characteristiccurrent responses gradually recovered and the oxidationcurrent increased at around 0.7 V in the positive going scan(Figure 1A(b)). This oxidation current should be due to theoxidative desorption of adsorbed S, together with theformation of Pt oxide,31 because the intensities of S 2p peakdecreased after the 15th (Figure 2A(c)) and almostdisappeared after the 150th potential cycle (Figure 2A(d)).Our recent results suggested that one of the major products ofS oxidation is SO2 at the Pt(111) surface.31,57 Some SO2desorbs from the surface to recover the ECSA, while theremaining SO2 can be reduced to elemental S adsorbed on Ptin the successive negative going scan. The current waves due tothe SO2 reduction were observed at around 0.1 V and −0.05 Vin the negative going scan of the 15th−150th potential cycles(Figure 1A(b)).In addition, a pair of peaks due to the hydrogen adsorption/desorption at the (110) substep54 newly appeared at around−0.15 V (Figure 1A(b)) and became larger as the number ofpotential cycles increased. This indicates that the surfaceatomic arrangement of Pt(111) changed by repeatingoxidation/reduction of Pt.58−60 CV measurements of S-freebare Pt(111) surface were also performed in a 0.1 M HClO4aqueous electrolyte solution and a small peak corresponding tothe formation of the (110) substep was observed after thepotential cycling up to 0.8 V vs Ag/AgCl for 150 times asshown in Figure S1. This suggests that the formation of the(110) substep occurs due to the potential cycling without theoxidative desorption of S. Nevertheless, since the (110) peak inFigure 1A(b) is slightly larger than that in Figure S1, theFigure 1. CVs of (a) bare and (b) S-adsorbed (A) Pt(111), (B) Pt3Co(111), (C) Pt3Fe(111), (D) Pt3Cu(111), and (E) Pt3Pd(111) electrodesmeasured in a 0.1 M HClO4 aqueous solution with a scan rate of 50 mV s−1. The CV of the bare Pt(111) electrode was shown as a dashed linetogether with those of bare Pt3M(111) electrodes. For the CVs of S-adsorbed electrodes, first (blue), 15th (green), 30th (orange), 60th (lightblue), 90th (pink), 120th (light green), and 150th cycles (red) were shown.Figure 2. Photoelectron spectra in the S 2p region of (a) bare and S-adsorbed (A) Pt(111), (B) Pt3Co(111), (C) Pt3Fe(111), (D) Pt3Cu(111),and (E) Pt3Pd(111) electrodes obtained (b) before and after the (c) 15th and (d) 150th potential cycles. The intensity of the S 2p spectra wasdivided by the integrated intensity of the corresponding Pt 4f spectra.The Journal of Physical Chemistry C pubs.acs.org/JPCC Articlehttps://doi.org/10.1021/acs.jpcc.4c06652J. Phys. Chem. C 2025, 129, 2122−21312124https://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.4c06652/suppl_file/jp4c06652_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.4c06652/suppl_file/jp4c06652_si_001.pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig2&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig2&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig2&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig2&ref=pdfpubs.acs.org/JPCC?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c06652?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asformation of the (110) site can be accelerated by the oxidationdesorption of S.Figure 3A shows Pt 4f photoelectron spectra of the S-adsorbed Pt(111) surfaces before and after the potential cyclestogether with that of the bare Pt(111) surface as a reference.The binding energies of the Pt 4f7/2 peaks were summarized inTable 1. At the S-adsorbed Pt(111) surface (Figure 3A(b),(c)), Pt 4f peaks shifted by 0.1 eV to a higher binding energyas compared to that of the bare Pt(111) surface (Figure3A(a)). After the desorption of S species (Figure 3A(d)),however, the Pt 4f peak reverted to the original position, thesame as that of the bare Pt(111) surface (Figure 3A(a)). Theshift of Pt 4f peaks is similar to but smaller than that reportedfor the Pt black catalyst where S is adsorbed with weak Pt−Selectronic interaction.56 These results suggest the electronicinteraction between adsorbed S and Pt at the S-adsorbedPt(111) surface as is the case of CO adsorbed Pt surface.513.2. Pt3Co(111) and Pt3Fe(111). Figure 1B,C shows CVsof bare and S-adsorbed Pt3Co(111) and Pt3Fe(111) singlecrystal electrodes measured in an Ar-purged 0.1 M HClO4aqueous electrolyte solution with a scan rate of 50 mV s−1. TheCVs of bare Pt3Co(111) (solid line in Figure 1B(a)) andPt3Fe(111) electrodes (solid line in Figure 1C(a)) weredifferent from that of pure Pt(111) electrode (solid line inFigure 1A(a) and dashed lines in Figure 1B(a),C(a)) but inaccordance with the CVs of previous report for Pt3Co(111)and Pt3Fe(111) electrodes covered with a Pt skin layer.61,62The positive potential end of hydrogen adsorption/desorptionwaves became narrower than that of the Pt(111) electrode(Figure 1B(a),C(a)). In addition, the hydroxyl adsorption/desorption peaks split into two components; a very smallshoulder peak at around 0.5 V that is almost the same potentialas the hydroxyl adsorption/desorption peak at the Pt(111)electrode and a positively shifted broad peak at around 0.6 V(Figure 1B(a),C(a)). Thus, the outermost layer of Pt3Co(111)and Pt3Fe(111) electrodes after induction heating in thepresent study is considered to be a Pt skin layer as previouslydemonstrated,61,62 resulting from the Pt surface segrega-tion.63,64After immersing the Pt skin-covered Pt3Co(111) andPt3Fe(111) electrodes in a 1 mM Na2S aqueous solution, thecharacteristic current responses disappeared (blue lines inFigure 1B(b),C(b)) and a pair of peaks corresponding toelemental S (163.2 eV20,55,56), as well as indistinct peaks due toSO2 (165.8 eV20,55,56) and SO42− (168.1 eV20,48,55,56),appeared in the S 2p region of photoelectron spectra (Figure2B(b) and Figure 2C(b)), showing the blocking of adsorption/desorption of hydrogen and hydroxyl species by the adsorbed Sspecies. As the number of potential cycles increased, thosemissing current responses gradually recovered (Figure 1B-B(b),C(b)). Simultaneously, the current attributable to theoxidation of adsorbed S species at around 0.7 V increased forboth electrodes (Figure 1B(b) and Figure 1C(b)). Theintensities of S 2p peaks significantly decreased after the15th potential cycle (Figure 2B(c),C(c)) and almostcompletely disappeared after the 150th potential cycle (Figure2B(d),C(d)). The intensities of S 2p peaks at the S-adsorbedPt3Co(111) and Pt3Fe(111) surfaces were similar to eachother under the same potential cycling conditions butsubstantially smaller than those of the Pt(111) surface (Figure2A(d)), implying the acceleration of oxidative desorption of Sby alloying with Co and Fe.In the case of Pt3Co(111), a pair of reversible peaksassignable to the hydrogen adsorption/desorption at the (110)substep54 appeared at around −0.15 V and became larger asthe number of potential cycles increased (Figure 1B(b)),indicating that the surface atomic arrangement of Pt-skinnedPt3Co(111) electrode changed during the potential cycling. InFigure 3. Photoelectron spectra in the Pt 4f region of (a) bare and S-adsorbed (A) Pt(111), (B) Pt3Co(111), (C) Pt3Fe(111), (D) Pt3Cu(111),and (E) Pt3Pd(111) electrodes obtained (b) before and after the (c) 15th and (d) 150th potential cycles. The spectrum of the bare Pt(111)electrode was shown in dashed line together with those of bare Pt3M(111) electrodes. All the spectra were normalized so that the integrated peakintensities become constant.Table 1. Binding Energies (eV) of the Pt 4f7/2 Peaks of Bare and S-Adsorbed Pt(111), Pt3Co(111), Pt3Fe(111), Pt3Cu(111),and Pt3Pd(111) Electrodes Obtained before and after the 15th and 150th Potential CyclesPt(111) Pt3Co(111) Pt3Fe(111) Pt3Cu(111) Pt3Pd(111)bare 71.8 71.9 71.9 71.7 71.6S-adsorbed (before potential cycling) 71.9 72.2 72.1 72.2 71.9after 15th cycle 71.9 72.2 72.2 71.8 71.9after 150th cycle 71.8 71.9 71.9 71.7 71.7The Journal of Physical Chemistry C pubs.acs.org/JPCC Articlehttps://doi.org/10.1021/acs.jpcc.4c06652J. Phys. Chem. C 2025, 129, 2122−21312125https://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig3&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig3&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig3&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig3&ref=pdfpubs.acs.org/JPCC?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c06652?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ascontrast, unlike the Pt(111) and Pt3Co(111) electrodes(Figure 1A(b),B(b)), the reversible peaks corresponding tothe hydrogen adsorption/desorption at the (110) substep wereabsent at the Pt3Fe(111) electrode after the 150th potentialcycle (Figure 1C(b)), indicating that the surface atomicarrangement of Pt-skinned Pt3Fe(111) electrode was main-tained during the potential cycles in this potential range. Sincethe surface roughening often produces low coordination Ptatoms that are less stable for dissolution as evidenced bothexperimentally and theoretically,65−67 the Pt3Fe(111) elec-trode with less surface roughening is potentially more tolerantto the adsorption/desorption of S and/or oxidation/reductionof Pt/Pt oxide by potential cycling.Figure 3B,C shows the Pt 4f photoelectron spectra of the S-adsorbed Pt3Co(111) and Pt3Fe(111) surfaces before and afterpotential cycles together with those of bare Pt3Co(111) andPt3Fe(111) surfaces as a reference. Consistent with theprevious reports,48,51 the binding energies of the Pt 4f peakof bare Pt3Co(111) and Pt3Fe(111) surfaces were higher thanthat of bare Pt(111) surface (Figure 3B(a),C(a) and Table 1),indicating that the electronic state of surface Pt atoms wasmodulated by alloying with Co and Fe due to the lattice strain(strain effect) and electronic interaction (ligand ef-fect).45,64,68−70 Yu et al. calculated the d-band center of thesurface layer of the surface segregated Pt3M alloys, where M isany of the three rows of transition metals (columns 3−12).64Ou et al. also calculated the d-band center for the Pt-segregated surface of various Pt3M alloys, where M is almostthe same as those reported by Yu et al.64 but except for Tc, Os,and Hg, and concluded that for 3d transition metals except forSc and Cu, both strain and ligand effects cause downshift of thed-band center of Pt-segregated surface.70 Note that bothstudies show close values for the d-band center in each alloy,albeit with slight differences. Thus, the shift of Pt 4f peak to ahigher binding energy, observed for Pt3Co(111) and Pt3Fe-(111), is considered to be brought about by the downshift ofthe d-band center away from the Fermi level.51At the S-adsorbed Pt3Co(111) and Pt3Fe(111) surfaces(Figure 3B(b),C(b)), the Pt 4f peak shifted by 0.3 and 0.2 eVto a higher binding energy than that at the bare Pt3Co(111)and Pt3Fe(111) surfaces (Figure 3B(a),C(a) and Table 1),respectively, suggesting the electronic interaction betweenadsorbed S and Pt at the S-adsorbed electrodes as described inthe preceding section (3.1). Whereas the peak positionremained unchanged in the photoelectron spectra after the15th potential cycle (Figure 3B(c),C(c) and Table 1), itreverted to the original position same as those of barePt3Co(111) and Pt3Fe(111) surfaces after the 150th potentialcycle (Figure 3B(d),C(d) and Table 1) where the S speciescompletely desorbed from the surface as evident by photo-electron spectra in S 2p region (Figure 2B(d),C(d)). Thisconfirms the occurrence of electronic interaction betweenadsorbed S and Pt at the S-adsorbed Pt3Co(111) andPt3Fe(111) surfaces. Thus, the trends of electrochemicalresponses and spectral features at the bare and S-adsorbedPt3Co(111) and Pt3Fe(111) electrodes were similar to eachother, except for the potentially higher tolerance of Pt3Fe(111)electrode to the surface roughening by potential cycling.3.3. Pt3Cu(111) and Pt3Pd(111). Figure 1D,E shows CVsof bare and S-adsorbed Pt3Cu(111) and Pt3Pd(111) singlecrystal electrodes measured in an Ar-purged 0.1 M HClO4aqueous electrolyte solution with a scan rate of 50 mV s−1. TheCV of bare Pt3Cu(111) electrode (Figure 1D(a)) exhibitedsimilar characteristics to those of Pt3Co(111) and Pt3Fe(111)electrodes (Figure 1B(a) and Figure 1C(a)) in the followingaspects; the hydrogen adsorption/desorption waves weredistorted and the hydroxyl adsorption/desorption peaks splitinto the two broad components. However, it is worth notinghere, with respect to Pt3Cu(111) that there are two notabledifferences from Pt3Co(111) and Pt3Fe(111). Whereas theshoulder peaks at around 0.5 V were much smaller than thepositively shifted peaks at 0.6 V at the Pt3Co(111) andPt3Fe(111) electrodes (Figure 1B(a),C(a)), the peak ataround 0.5 V was comparable to positively shifted ones(Figure 1D(a)). In addition, the positively shifted peak wasobserved at around 0.7 V (Figure 1D(a)), which is 0.1 V morepositive than those at the Pt3Co(111) and Pt3Fe(111)electrodes (Figure 1B(a),C(a)). Notably, theoretical calcu-lations predicted that a Pt surface segregation in Pt3Cu(111) iseither weak63 or possible but not strong,64,70 and for Pt−Cualloys, both experimental and theoretical studies suggested thatthe Pt segregation tends not to be so obvious and varies withconditions.71−73 Jensen et al. reported that the positivepotential shift of the adsorption/desorption peaks of hydroxylspecies became larger as increasing the Cu content at the Cu/Pt(111) near-surface alloy.72 They also reported that thehydroxyl adsorption/desorption peaks reached 0.69 V when aPt skin layer was formed on a complete monatomic Cu secondlayer. Thus, the surface of the Pt3Cu(111) electrode in thepresent study was probably covered by the Pt skin outermostlayer formed on the Cu second layer but partially phase-separated.The CV of the bare Pt3Pd(111) electrode (solid line ofFigure 1E(a)) was distinctively different not only from that ofthe pure Pt(111) electrode (solid line of Figure 1A(a) anddashed line of Figure 1E(a)) but also from those of any otherPt3M(111) electrodes examined in this study (solid lines ofFigure 1B−D(a)); a new reversible peak appeared at around0.05 V and the hydroxyl adsorption/desorption peaks becamebroader and shifted to negative potential as compared to theCV of the Pt(111) electrode (solid line of Figure 1A(a) anddashed line of Figure 1E(a)). Also notably here, theoreticalcalculations predicted little Pt segregation on the surfaces ofPt3Pd(111),63,64,70 and both experimental and theoreticalstudies indicated that no preferred surface segregation of Ptoccurs in Pt−Pd alloys, but rather that Pd would enrich theoutermost layer of alloys.73−75 The characteristics of CVobserved for bare Pt3Pd(111) electrode imply that hydrogenand hydroxyl species adsorb on the Pt3Pd(111) electrode morestrongly than on the Pt(111) electrode76 probably due to theupshift of d-band center.64,70,77After immersing the Pt3Cu(111) and Pt3Pd(111) electrodesin a 1 mM Na2S aqueous solution, those characteristic currentresponses disappeared (blue lines in Figure 1D(b) and Figure1E(b)) and doublet peaks corresponding to adsorbedelemental S (163.3 eV20,55,56) and very small peaks due toSO2 (165.7 eV20,55,56) and SO42− (168.4 eV20,48,55,56)appeared in the S 2p region of photoelectron spectra (Figure2D(b) and Figure 2E(b)). One may be concerned with theformation of CuS at the Pt3Cu(111) surface, but the positionof the S 2p peak of the S-adsorbed Pt3Cu(111) surface wastotally different from that of CuS deposited on a polycrystallinePt surface as shown in Figure S2 and previous report.78 Theintensity of the S 2p peak at the S-adsorbed Pt3Cu(111)surface shown in Figure 2D(b) is slightly smaller than those ofThe Journal of Physical Chemistry C pubs.acs.org/JPCC Articlehttps://doi.org/10.1021/acs.jpcc.4c06652J. Phys. Chem. C 2025, 129, 2122−21312126https://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.4c06652/suppl_file/jp4c06652_si_001.pdfpubs.acs.org/JPCC?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c06652?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asthe other surfaces, implying its potentially high tolerance to Sadsorption.Interestingly, in addition to a small current peak at around0.2 V, oxidation current significantly larger than those of theother electrodes (blue lines in Figure 1A−C,E(b)) started tobe observed from around 0.6 V only in the first potential cycleof the S-adsorbed Pt3Cu(111) electrode (blue line in Figure1D(b)). The small current peak can be attributed to thedissolution of Cu from the phase-separated Cu domainbecause the potential is in reasonable agreement with theredox potential of Cu, originally reported as 0.342 V vs SHE.79This small oxidation peak was not observed at the barePt3Cu(111) surface but only after the S adsorption, suggestingthat the dissolution of phase-separated Cu was accelerated byadsorbed S species as previously reported.80,81 The largeoxidation current rising from 0.6 V should be due to theoxidation of adsorbed S because the current wave correspond-ing to the reduction of SO2 at around −0.1 V in the successivenegative going scan of the first potential cycle (blue line inFigure 1D(b))31 was also larger than those of the otherelectrodes (blue lines in Figure 1A−C,E(b)). Moreover, the S2p peak of the S-adsorbed Pt3Cu(111) surface almostdisappeared after the 15th potential cycle (Figure 2D(c))although the S 2p peaks were still present at the surfaces ofother electrodes at this stage (Figure 2A−C,E(c)), indicatingthat the oxidative desorption of S at the Pt3Cu(111) surface isfaster than the others. By repeating the potential cycles, thehydrogen and hydroxyl adsorption/desorption current wavesrecovered gradually and almost reverted to the original shapescharacteristic of the bare Pt3Cu(111) electrode after the 90thpotential cycle (pink line in Figure 1D(b)). This confirms thatdespite the dissolution of phase-separated Cu, the atomicarrangement of the Pt3Cu(111) electrode was almostmaintained.As the number of potential cycles increased at the S-adsorbed Pt3Pd(111) electrode, the hydrogen adsorption/desorption waves gradually recovered (Figure 1E(b)).However, the intensity of the S 2p peak after the 15thpotential cycle (Figure 2E(c)) was much larger than those ofPt(111) and other Pt3M(111) electrodes (Figure 2A−D(c)),suggesting that the oxidative desorption of S at the Pt3Pd(111)electrode is slower than the others. Even after the 150thpotential cycle where the hydrogen adsorption/desorptionwaves almost completely recovered at the other Pt3M(111)electrodes (dashed lines and red lines in Figure 1B−D(b)), itrecovered only up to 46% of that of the original barePt3Pd(111) electrode (dashed line and red line in Figure1E(b)). In addition, the reversible peak observed at around0.05 V, which is characteristic to the bare Pt3Pd(111) electrode(solid line in Figure 1E(a) and dashed line in Figure 1E(b))was missing and the shape of CV (red line in Figure 1E(b))resembles that of bare pure Pt(111) electrode (Figure 1A(a)and dashed line in Figure 1E(a)). These characteristics areprobably due to the enhancement of S adsorption by thepresence of Pd in the outermost layer.82Figure 3D,E shows Pt 4f photoelectron spectra of the S-adsorbed Pt3Cu(111) and Pt3Pd(111) surfaces before andafter the potential cycles together with those of barePt3Cu(111) and Pt3Pd(111) surfaces as a reference. Incontrast to the Pt3Co(111) and Pt3Fe(111) surfaces, thebinding energies of Pt 4f peak of bare Pt3Cu(111) andPt3Pd(111) surfaces were lower by 0.1 and 0.2 eV than that ofbare Pt(111) surface (Figure 3D(a),E(a) and Table 1). This isconsistent with the previous reports at the Pt3Pd(111)surface.83,84The ligand effect of transition metals was reported togenerally cause a downshift of the d-band center of Pt-segregated surface in most Pt3M alloys, except for those inwhich M has fully occupied the outermost d orbitals.70Although Cu has fully occupied 3d orbitals that bring aboutthe upshift of the d-band center, its smaller atomic radiuscauses the downshift and, as a result, ligand and strain effects ofCu are nearly canceled out.70 On the other hand, since Pd hasfully occupied 4d orbitals and an atomic radius similar to Pt,the ligand effect is more dominant, leading to the upshift of thed-band center toward the Fermi level.70 Thus, the shift of thePt 4f peak to a lower binding energy at the Pt3Pd(111)electrode is more prominent than that of the Pt3Cu(111)electrode.At the S-adsorbed Pt3Cu(111) and Pt3Pd(111) surfaces(Figure 3D(b) and Figure 3E(b)), the Pt 4f peaks shifted by0.5 and 0.3 eV to a higher binding energy than those of barePt3Cu(111) and Pt3Pd(111) surfaces (Figure 3D(a),E(a) andTable 1), respectively, presumably due to the electronicinteraction between adsorbed S and Pt. The Pt 4f peak of theS-adsorbed Pt3Cu(111) surface shifted to a lower bindingenergy after the 15th potential cycle (Figure 3D(c) and Table1) where the S 2p peak almost disappeared, and completelyrecovered to the original position of bare Pt3Cu(111) surfaceafter 150th potential cycle (Figure 3D(d) and Table 1). In thecase of the S-adsorbed Pt3Pd(111) surface, however, theposition of the Pt 4f peak remained almost unchanged after the15th potential cycle (Figure 3E(c) and Table 1) and it was stillhigher by 0.1 eV than that of the bare Pt3Pd(111) surface evenafter the 150th potential cycle (Figure 3E(d) and Table 1).Thus, we confirmed the electronic interaction betweenadsorbed S and Pt at the S-adsorbed Pt(111) and all of thePt3M(111) surfaces.3.4. Recovery Rate. To elucidate the effect of alloying onthe oxidative desorption of S species, the recovery factor, RF isdefined as eq 1 based on the electrochemical chargeintegrations of hydrogen desorption current at the Pt(111)and Pt3M(111) electrodes.= CCRF S adsorbedbare (1)where CS‑adsorbed and Cbare are the charge integrations ofhydrogen desorption waves at the S-adsorbed electrodes afterpotential cycling and bare electrodes, respectively. Figure 4shows the plot of RF with respect to the number of potentialcycles.Figure 4. Recovery factor, RF, of the S-adsorbed Pt(111),Pt3Co(111), Pt3Fe(111), Pt3Cu(111), and Pt3Pd(111) electrodesagainst the number of potential cycles.The Journal of Physical Chemistry C pubs.acs.org/JPCC Articlehttps://doi.org/10.1021/acs.jpcc.4c06652J. Phys. Chem. C 2025, 129, 2122−21312127https://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig4&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig4&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig4&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig4&ref=pdfpubs.acs.org/JPCC?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c06652?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asRFs were higher at the Pt3Cu(111), Pt3Co(111), Pt3Fe-(111), Pt(111), and Pt3Pd(111) electrodes in that order up tothe 90th cycle, and the RF of the Pt3Co(111) electrodebecame higher than that of the Pt3Cu(111) electrode from the120th cycle. Except for the Pt3Pd(111) electrode, RFs of thePt3M(111) electrodes were higher than those of the Pt(111)electrode. It is noted that RFs of the Pt3Co(111) electrode atthe 120th and 150th cycles became larger than 1, due to thesurface roughening caused by the oxidation/reduction cycles.Ligand effect and strain effect are considered as thedominant factors for RFs and thus RFs after 150th potentialcycles were plotted with respect to the binding energies of Pt4f peaks of Pt(111) and Pt3M(111) electrodes before and afterthe adsorption of S species and atomic radii of Pt and foreignmetal M (Figure 5). Whereas the correlation between RF andbinding energy of the Pt 4f peak of bare Pt(111) andPt3M(111) electrodes was unclear (Figure 5(a)), RFmonotonically increased as the Pt 4f peaks of S-adsorbedPt(111) and Pt3M(111) electrodes became higher (Figure5(b)). This result suggests that the electronic structure of S-adsorbed Pt(111) and Pt3M(111) electrodes is one of theimportant factors because the shift of the Pt 4f peak to a higherbinding energy represents the downshift of the d-band centeraway from the Fermi level as discussed in the sections above.Thus, the downshift of the d-band center caused by both theligand effect of foreign metal M and electronic interactionbetween adsorbed S and Pt atoms substantially accelerates theelectrochemical oxidative desorption of S species. In addition,RF became higher as the atomic radii of foreign metal Mbecame smaller (Figure 5(c)). The difference in atomic radii ofPt and foreign metal M is the measure of another importantfactor, the strain effect. The strain introduced by alloying Ptwith a foreign metal with a smaller atomic radius also promotesthe oxidative desorption of the S species.4. CONCLUSIONSWe investigated the oxidative desorption behavior of S specieson the Pt(111), Pt3Co(111), Pt3Fe(111), Pt3Cu(111), andPt3Pd(111) electrodes by electrochemical measurements andXPS. We confirmed that the adsorption and desorption ofhydrogen and hydroxyl species were blocked by adsorbed Sspecies on the electrode surfaces. However, the adsorbed Sspecies oxidatively desorbed from the electrode surfaces by thepotential cycling. The oxidative desorption of S species, i.e.,recovery from the S poisoning was slower at the Pt3Pd(111)electrode than at the Pt(111) electrode, whereas it was faster atthe Pt3Cu(111), Pt3Co(111) and Pt3Fe(111) electrodes thanat the Pt(111) electrode in that order. This trend was ruled bythe downshift of the d-band center due to the ligand effect offoreign metal and electronic interaction between adsorbed Sand Pt, as well as the strain effect. Thus, the S oxidativedesorption capability of Pt electrocatalysts can be improved byalloying with foreign metals, especially with a smaller atomicradius.■ ASSOCIATED CONTENT*sı Supporting InformationThe Supporting Information is available free of charge athttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652.Potential cycling experiment for S-free bare Pt(111)electrode; XPS measurements of Pt3Cu(111) surfaceand CuS deposited on polycrystalline Pt surface (PDF)■ AUTHOR INFORMATIONCorresponding AuthorTakuya Masuda − Research Center for Energy andEnvironmental Materials (GREEN), National Institute forMaterials Science (NIMS), Tsukuba, Ibaraki 305-0044,Japan; Graduate School of Chemical Sciences andEngineering, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan; orcid.org/0000-0001-7462-2177;Email: MASUDA.Takuya@nims.go.jpAuthorsMakoto Aoki − Research Center for Energy andEnvironmental Materials (GREEN), National Institute forMaterials Science (NIMS), Tsukuba, Ibaraki 305-0044,Japan; Present Address: Toyota Boshoku Corporation,Kariya, Aichi 448-8651, JapanTamao Shishido − Research Center for Energy andEnvironmental Materials (GREEN), National Institute forMaterials Science (NIMS), Tsukuba, Ibaraki 305-0044,JapanTetsuro Morooka − Research Center for Energy andEnvironmental Materials (GREEN), National Institute forMaterials Science (NIMS), Tsukuba, Ibaraki 305-0044,JapanTakuya Nakanishi − Research Center for Energy andEnvironmental Materials (GREEN), National Institute forMaterials Science (NIMS), Tsukuba, Ibaraki 305-0044,Japan; orcid.org/0000-0002-1172-718XComplete contact information is available at:https://pubs.acs.org/10.1021/acs.jpcc.4c06652Figure 5. RFs after 150th potential cycles with respect to the binding energy of Pt 4f peaks of Pt(111), Pt3Co(111), Pt3Fe(111), Pt3Cu(111), andPt3Pd(111) electrodes (a) before and (b) after the adsorption of S species and (c) atomic radii of Pt for the Pt(111) electrode and foreign metal M(Co, Fe, Cu, Pd) for Pt3M(111) electrodes.The Journal of Physical Chemistry C pubs.acs.org/JPCC Articlehttps://doi.org/10.1021/acs.jpcc.4c06652J. Phys. Chem. C 2025, 129, 2122−21312128https://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?goto=supporting-infohttps://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.4c06652/suppl_file/jp4c06652_si_001.pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Takuya+Masuda"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://orcid.org/0000-0001-7462-2177mailto:MASUDA.Takuya@nims.go.jphttps://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="Tamao+Shishido"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://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="Takuya+Nakanishi"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://orcid.org/0000-0002-1172-718Xhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig5&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig5&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig5&ref=pdfhttps://pubs.acs.org/doi/10.1021/acs.jpcc.4c06652?fig=fig5&ref=pdfpubs.acs.org/JPCC?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c06652?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asNotesThe 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).■ 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 (10), 3904−3951.(2) Mancino, A. N.; Menale, C.; Vellucci, F.; Pasquali, M.; Bubbico,R. PEM Fuel Cell Applications in Road Transport. Energies 2023, 16(17), 6129.(3) Moore, J. M.; Adcock, P. L.; Lakeman, J. B.; Mepsted, G. O. Theeffects of battlefield contaminants on PEMFC performance. J. PowerSources 2000, 85 (2), 254−260.(4) Bernard Rodríguez, C. R.; Santana, J. A. Adsorption anddiffusion of sulfur on the (111), (100), (110), and (211) surfaces ofFCC metals: Density functional theory calculations. J. Chem. Phys.2018, 149 (20), No. 204701.(5) Mohtadi, R.; Lee, W. K.; Van Zee, J. W. The effect oftemperature on the adsorption rate of hydrogen sulfide on Pt anodesin a PEMFC. Applied Catalysis B: Environmental 2005, 56 (1), 37−42.(6) Nagahara, Y.; Sugawara, S.; Shinohara, K. The impact of aircontaminants on PEMFC performance and durability. J. Power Sources2008, 182 (2), 422−428.(7) 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 (1), 89−95.(8) Marcus, P.; Protopopoff, E. Coadsorption of sulphur andhydrogen on platinum (110) studied by radiotracer and electro-chemical techniques. Surf. Sci. 1985, 161 (2), 533−552.(9) Batina, N.; McCargar, J. W.; Salaita, G. N.; Lu, F.; Laguren-Davidson, L.; Lin, C. H.; Hubbard, A. T. Structure and compositionof platinum(111) and platinum(100) surfaces as a function ofelectrode potential in aqueous sulfide solutions. Langmuir 1989, 5(1), 123−128.(10) 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 (1), 194−200.(11) 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 (1), 254−266.(12) Maurice, V.; Marcus, P. STM imaging in air with atomicresolution of adsorbates on metal surfaces: Pt(100)-c(2 × 2)s. Surf.Sci. 1992, 262 (1), L59−L64.(13) 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*. Journal of VacuumScience & Technology B: Microelectronics and Nanometer StructuresProcessing, Measurement, and Phenomena 1994, 12 (3), 1751−1753.(14) Shi, W.; Yi, B.; Hou, M.; Jing, F.; Ming, P. Hydrogen sulfidepoisoning and recovery of PEMFC Pt-anodes. J. Power Sources 2007,165 (2), 814−818.(15) Fu, J.; Hou, M.; Du, C.; Shao, Z.; Yi, B. Potential dependenceof sulfur dioxide poisoning and oxidation at the cathode of protonexchange membrane fuel cells. J. Power Sources 2009, 187 (1), 32−38.(16) 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 (27), 11886−11897.(17) 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 (4), 747−752.(18) 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 (5), 1331−1340.(19) Potgieter, M.; Parrondo, J.; Ramani, V. K.; Kriek, R. J.Evaluation of Polycrystalline Platinum and Rhodium Surfaces for theElectro-Oxidation of Aqueous Sulfur Dioxide. Electrocatalysis 2016, 7(1), 50−59.(20) Chen, C.-H.; Halford, A.; Walker, M.; Brennan, C.; Lai, S. C. S.;Fermin, D. J.; Unwin, P. R.; Rodriguez, P. Electrochemicalcharacterization and regeneration of sulfur poisoned Pt catalysts inaqueous media. J. Electroanal. Chem. 2018, 816, 138−148.(21) Ke, S.; Sun, C.; Cui, B.; Qin, Y.; Dou, M. Operatable andEfficient Mitigation Strategies for H2S Poisoning in Proton ExchangeMembrane Fuel Cells: Releasing Pt Reactive Sites for HydrogenOxidation. ACS Applied Energy Materials 2023, 6 (6), 3337−3346.(22) Clavilier, J.; Faure, R.; Guinet, G.; Durand, R. Preparation ofmonocrystalline Pt microelectrodes and electrochemical study of theplane surfaces cut in the direction of the {111} and {110} planes.Journal of Electroanalytical Chemistry and Interfacial Electrochemistry1980, 107 (1), 205−209.(23) Masuda, T.; Uosaki, K., Novel In Situ Techniques. InElectrochemical Science for a Sustainable Society: A Tribute to JohnO’M Bockris, Uosaki, K., Ed. Springer International Publishing: Cham,2017; pp 147−174.(24) Alfonso, D. R. Computational Studies of ExperimentallyObserved Structures of Sulfur on Metal Surfaces. J. Phys. Chem. C2011, 115 (34), 17077−17091.(25) 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 (5), 558.(26) Ungerer, M. J.; van Sittert, C. G. C. E.; de Leeuw, N. H.Behavior of S, SO, and SO3 on Pt (001), (011), and (111) surfaces: ADFT study. J. Chem. Phys. 2021, 154 (19), No. 194701.(27) 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 (1), 243−250.(28) 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 (6), 1019−1030.(29) Dourado, A. H. B.; Colle, V. D.; Munhos, R. L.; Feliu, J. M.;Varela, H.; de Torresi, S. I. C. SO2 electrooxidation reaction on Ptsingle crystal surfaces in acidic media: Electrochemical and in situFTIR studies. Electrochim. Acta 2022, 403, No. 139601.(30) Kattwinkel, L.; Magnussen, O. M. Optical reflectance studies onthe oxidation of chemisorbed sulfur at the Pt(111) electrode.Electrochim. Acta 2022, 434, No. 141297.(31) Morooka, T.; Shishido, T.; Devivaraprasad, R.; Elumalai, G.;Aoki, M.; Shirasawa, T.; Nakanishi, T.; Ishikawa, A.; Kondo, T.;Masuda, T. Potential-Dependent and Face Orientation-DependentElectrochemical Oxidative Desorption Behavior of Sulfur SpeciesAdsorbed on Platinum Single-Crystal Surfaces. J. Phys. Chem. C 2024,128, 16426−16436.(32) Mukerjee, S.; Srinivasan, S. Enhanced electrocatalysis of oxygenreduction on platinum alloys in proton exchange membrane fuel cells.J. Electroanal. Chem. 1993, 357 (1), 201−224.(33) Toda, T.; Igarashi, H.; Uchida, H.; Watanabe, M. Enhancementof the Electroreduction of Oxygen on Pt Alloys with Fe, Ni, and Co. J.Electrochem. Soc. 1999, 146 (10), 3750.(34) Min, M.-k.; Cho, J.; Cho, K.; Kim, H. Particle size and alloyingeffects of Pt-based alloy catalysts for fuel cell applications. Electrochim.Acta 2000, 45 (25), 4211−4217.(35) Stamenkovic,́ V.; Schmidt, T. J.; Ross, P. N.; Markovic,́ N. M.Surface Composition Effects in Electrocatalysis: Kinetics of OxygenReduction on Well-Defined Pt3Ni and Pt3Co Alloy Surfaces. J. Phys.Chem. B 2002, 106, 11970−11979.The Journal of Physical Chemistry C pubs.acs.org/JPCC Articlehttps://doi.org/10.1021/acs.jpcc.4c06652J. Phys. Chem. C 2025, 129, 2122−21312129https://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/10.3390/en16176129https://doi.org/10.1016/S0378-7753(99)00341-9https://doi.org/10.1016/S0378-7753(99)00341-9https://doi.org/10.1063/1.5063464https://doi.org/10.1063/1.5063464https://doi.org/10.1063/1.5063464https://doi.org/10.1016/j.apcatb.2004.08.012https://doi.org/10.1016/j.apcatb.2004.08.012https://doi.org/10.1016/j.apcatb.2004.08.012https://doi.org/10.1016/j.jpowsour.2007.12.091https://doi.org/10.1016/j.jpowsour.2007.12.091https://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/10.1016/0039-6028(85)90826-Xhttps://doi.org/10.1016/0039-6028(85)90826-Xhttps://doi.org/10.1016/0039-6028(85)90826-Xhttps://doi.org/10.1021/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/10.1021/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/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/10.1016/0039-6028(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/j.jpowsour.2006.12.052https://doi.org/10.1016/j.jpowsour.2006.12.052https://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/10.1016/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/10.1021/acsaem.2c04026?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsaem.2c04026?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsaem.2c04026?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsaem.2c04026?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1016/S0022-0728(79)80022-4https://doi.org/10.1016/S0022-0728(79)80022-4https://doi.org/10.1016/S0022-0728(79)80022-4https://doi.org/10.1021/jp2048426?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp2048426?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.3390/catal10050558https://doi.org/10.3390/catal10050558https://doi.org/10.1063/5.0043501https://doi.org/10.1063/5.0043501https://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/10.1016/S0013-4686(98)00206-0https://doi.org/10.1016/S0013-4686(98)00206-0https://doi.org/10.1016/j.electacta.2021.139601https://doi.org/10.1016/j.electacta.2021.139601https://doi.org/10.1016/j.electacta.2021.139601https://doi.org/10.1016/j.electacta.2022.141297https://doi.org/10.1016/j.electacta.2022.141297https://doi.org/10.1021/acs.jpcc.4c03227?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acs.jpcc.4c03227?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acs.jpcc.4c03227?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1016/0022-0728(93)80380-Zhttps://doi.org/10.1016/0022-0728(93)80380-Zhttps://doi.org/10.1149/1.1392544https://doi.org/10.1149/1.1392544https://doi.org/10.1016/S0013-4686(00)00553-3https://doi.org/10.1016/S0013-4686(00)00553-3https://doi.org/10.1021/jp021182h?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp021182h?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-aspubs.acs.org/JPCC?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c06652?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as(36) Yano, H.; Kataoka, M.; Yamashita, H.; Uchida, H.; Watanabe,M. Oxygen Reduction Activity of Carbon-Supported Pt−M (M = V,Ni, Cr, Co, and Fe) Alloys Prepared by Nanocapsule Method.Langmuir 2007, 23 (11), 6438−6445.(37) Zhang, X.; Li, H.; Yang, J.; Lei, Y.; Wang, C.; Wang, J.; Tang,Y.; Mao, Z. Recent advances in Pt-based electrocatalysts for PEMFCs.RSC Adv. 2021, 11 (22), 13316−13328.(38) Ahn, C.-Y.; Park, J. E.; Kim, S.; Kim, O.-H.; Hwang, W.; Her,M.; Kang, S. Y.; Park, S.; Kwon, O. J.; Park, H. S.; et al. Differences inthe Electrochemical Performance of Pt-Based Catalysts Used forPolymer Electrolyte Membrane Fuel Cells in Liquid Half- and Full-Cells. Chem. Rev. 2021, 121 (24), 15075−15140.(39) Kitchin, J. R.; No̷rskov, J. K.; Barteau, M. A.; Chen, J. G.Modification of the surface electronic and chemical properties ofPt(111) by subsurface 3d transition metals. J. Chem. Phys. 2004, 120(21), 10240−6.(40) Xu, Y.; Ruban, A. V.; Mavrikakis, M. Adsorption andDissociation of O2 on Pt−Co and Pt−Fe Alloys. J. Am. Chem. Soc.2004, 126 (14), 4717−4725.(41) Stamenkovic, V. R.; Mun, B. S.; Arenz, M.; Mayrhofer, K. J. J.;Lucas, C. A.; Wang, G.; Ross, P. N.; Markovic, N. M. Trends inelectrocatalysis on extended and nanoscale Pt-bimetallic alloysurfaces. Nat. Mater. 2007, 6 (3), 241−247.(42) Ma, Y.; Balbuena, P. B. Surface Properties and DissolutionTrends of Pt3M Alloys in the Presence of Adsorbates. J. Phys. Chem. C2008, 112 (37), 14520−14528.(43) Greeley, J.; Stephens, I. E. L.; Bondarenko, A. S.; Johansson, T.P.; Hansen, H. A.; Jaramillo, T. F.; Rossmeisl, J.; Chorkendorff, I.;Nørskov, J. K. Alloys of platinum and early transition metals as oxygenreduction electrocatalysts. Nat. Chem. 2009, 1 (7), 552−556.(44) Duan, Z.; Wang, G. A first principles study of oxygen reductionreaction on a Pt(111) surface modified by a subsurface transitionmetal M (M = Ni, Co, or Fe). Phys. Chem. Chem. Phys. 2011, 13 (45),20178−20187.(45) Lim, C.; Fairhurst, A. R.; Ransom, B. J.; Haering, D.;Stamenkovic, V. R. Role of Transition Metals in Pt Alloy Catalystsfor the Oxygen Reduction Reaction. ACS Catal. 2023, 13 (22),14874−14893.(46) Pillay, D.; Johannes, M. D. Effect of S on Pt(111) andPt3Ni(111) Surfaces: A First Principles Study. J. Phys. Chem. C 2008,112 (5), 1544−1551.(47) Pillay, D.; Johannes, M. D.; Garsany, Y.; Swider-Lyons, K. E.Poisoning of Pt3Co Electrodes: A Combined Experimental and DFTStudy. J. Phys. Chem. C 2010, 114 (17), 7822−7830.(48) Ke, S.; Qiu, L.; Zhao, W.; Sun, C.; Cui, B.; Xu, G.; Dou, M.Understanding of Correlation between Electronic Properties andSulfur Tolerance of Pt-Based Catalysts for Hydrogen Oxidation. ACSAppl. Mater. Interfaces 2022, 14 (6), 7768−7778.(49) Ke, S.; Cui, B.; Sun, C.; Qin, Y.; Zhang, J.; Dou, M. IntriguingH2S Tolerance of the PtRu Alloy for Hydrogen Oxidation Catalysis inPEMFCs: Weakened Pt−S Binding with Slower Adsorption Kinetics.ACS Appl. Mater. Interfaces 2022, 14 (42), 47765−47774.(50) Watanabe, M.; Motoo, S. Electrocatalysis by ad-atoms: Part III.Enhancement of the oxidation of carbon monoxide on platinum byruthenium ad-atoms. Journal of Electroanalytical Chemistry andInterfacial Electrochemistry 1975, 60 (3), 275−283.(51) Wakisaka, M.; Mitsui, S.; Hirose, Y.; Kawashima, K.; Uchida,H.; Watanabe, M. Electronic Structures of Pt−Co and Pt−Ru Alloysfor CO-Tolerant Anode Catalysts in Polymer Electrolyte Fuel CellsStudied by EC−XPS. J. Phys. Chem. B 2006, 110 (46), 23489−23496.(52) Shatkay, A.; Lerman, A. Individual activities of sodium andchloride ions in aqueous solutions of sodium chloride. Anal. Chem.1969, 41 (3), 514−517.(53) Rabie, H. R.; Wilczek-Vera, G.; Vera, J. H. Activities ofIndividual Ions From Infinite Dilution to Saturated Solutions. J.Solution Chem. 1999, 28 (7), 885−913.(54) Rizo, R.; Herrero, E.; Climent, V.; Feliu, J. M. On the nature ofadsorbed species on platinum single-crystal electrodes. CurrentOpinion in Electrochemistry 2023, 38, No. 101240.(55) Garsany, Y.; Baturina, O. A.; Swider-Lyons, K. E. Impact ofSulfur Dioxide on the Oxygen Reduction Reaction at Pt/VulcanCarbon Electrocatalysts. J. Electrochem. Soc. 2007, 154 (7), B670.(56) Paál, Z.; Matusek, K.; Muhler, M. Sulfur adsorbed on Ptcatalyst: its chemical state and effect on catalytic properties as studiedby electron spectroscopy and n-hexane test reactions. AppliedCatalysis A: General 1997, 149 (1), 113−132.(57) Loucǩa, T. Adsorption and oxidation of sulphur and of sulphurdioxide at the platinum electrode. Journal of ElectroanalyticalChemistry and Interfacial Electrochemistry 1971, 31 (2), 319−332.(58) Clavilier, J.; Armand, D. Electrochemical induction of changesin the distribution of the hydrogen adsorption states on Pt (100) andPt (111) surfaces in contact with sulphuric acid solution. Journal ofElectroanalytical Chemistry and Interfacial Electrochemistry 1986, 199(1), 187−200.(59) Itaya, K.; Sugawara, S.; Sashikata, K.; Furuya, N. In situscanning tunneling microscopy of platinum (111) surface with theobservation of monatomic steps. Journal of Vacuum Science &Technology A 1990, 8 (1), 515−519.(60) 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 (3), 286−287.(61) Wakisaka, M.; Kobayashi, S.; Morishima, S.; Hyuga, Y.; Tryk,D. A.; Watanabe, M.; Iiyama, A.; Uchida, H. Unprecedenteddependence of the oxygen reduction activity on Co content at PtSkin/Pt−Co(111) single crystal electrodes. Electrochem. Commun.2016, 67, 47−50.(62) Suzuki, A.; Nakamura, M.; Hoshi, N. Effects of SurfaceStructures and Hydrophobic Species on the Oxygen ReductionReaction Activity of Pt3Fe Single-Crystal Electrodes. Electrocatalysis2022, 13, 175−181.(63) Ma, Y.; Balbuena, P. B. Pt surface segregation in bimetallicPt3M alloys: A density functional theory study. Surf. Sci. 2008, 602(1), 107−113.(64) Yu, T. H.; Sha, Y.; Merinov, B. V.; Goddard, W. A., IIIImproved Non-Pt Alloys for the Oxygen Reduction Reaction at FuelCell Cathodes Predicted from Quantum Mechanics. J. Phys. Chem. C2010, 114 (26), 11527−11533.(65) Holby, E. F.; Sheng, W.; Shao-Horn, Y.; Morgan, D. Ptnanoparticle stability in PEM fuel cells: influence of particle sizedistribution and crossover hydrogen. Energy Environ. Sci. 2009, 2 (8),865−871.(66) Jinnouchi, R.; Toyoda, E.; Hatanaka, T.; Morimoto, Y. FirstPrinciples Calculations on Site-Dependent Dissolution Potentials ofSupported and Unsupported Pt Particles. J. Phys. Chem. C 2010, 114(41), 17557−17568.(67) 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 (2), 140−147.(68) Mavrikakis, M.; Hammer, B.; Nørskov, J. K. Effect of Strain onthe Reactivity of Metal Surfaces. Phys. Rev. Lett. 1998, 81 (13), 2819−2822.(69) Kitchin, J. R.; Nørskov, J. K.; Barteau, M. A.; Chen, J. G. Roleof Strain and Ligand Effects in the Modification of the Electronic andChemical Properties of Bimetallic Surfaces. Phys. Rev. Lett. 2004, 93(15), No. 156801.(70) Ou, L.; Chen, S. DFT calculation analysis of oxygen reductionactivity and stability of bimetallic catalysts with Pt-segregated surface.Science China Chemistry 2015, 58 (4), 586−592.(71) Oezaslan, M.; Hasché, F.; Strasser, P. PtCu3, PtCu and Pt3CuAlloy Nanoparticle Electrocatalysts for Oxygen Reduction Reaction inAlkaline and Acidic Media. J. Electrochem. Soc. 2012, 159 (4), B444.(72) Jensen, K. D.; Tymoczko, J.; Rossmeisl, J.; Bandarenka, A. S.;Chorkendorff, I.; Escudero-Escribano, M.; Stephens, I. E. L.Elucidation of the Oxygen Reduction Volcano in Alkaline Mediausing a Copper−Platinum(111) Alloy. Angew. Chem., Int. Ed. 2018, 57(11), 2800−2805.The Journal of Physical Chemistry C pubs.acs.org/JPCC Articlehttps://doi.org/10.1021/acs.jpcc.4c06652J. Phys. Chem. C 2025, 129, 2122−21312130https://doi.org/10.1021/la070078u?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/la070078u?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1039/D0RA05468Bhttps://doi.org/10.1021/acs.chemrev.0c01337?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acs.chemrev.0c01337?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acs.chemrev.0c01337?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acs.chemrev.0c01337?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/ja031701+?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/ja031701+?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1038/nmat1840https://doi.org/10.1038/nmat1840https://doi.org/10.1038/nmat1840https://doi.org/10.1021/jp8046888?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp8046888?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1038/nchem.367https://doi.org/10.1038/nchem.367https://doi.org/10.1039/c1cp21687bhttps://doi.org/10.1039/c1cp21687bhttps://doi.org/10.1039/c1cp21687bhttps://doi.org/10.1021/acscatal.3c03321?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acscatal.3c03321?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp077104h?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp077104h?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp906778k?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp906778k?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.1c18905?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.1c18905?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.2c13742?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.2c13742?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.2c13742?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1016/S0022-0728(75)80262-2https://doi.org/10.1016/S0022-0728(75)80262-2https://doi.org/10.1016/S0022-0728(75)80262-2https://doi.org/10.1021/jp0653510?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp0653510?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp0653510?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://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.coelec.2023.101240https://doi.org/10.1016/j.coelec.2023.101240https://doi.org/10.1149/1.2736648https://doi.org/10.1149/1.2736648https://doi.org/10.1149/1.2736648https://doi.org/10.1016/S0926-860X(96)00253-0https://doi.org/10.1016/S0926-860X(96)00253-0https://doi.org/10.1016/S0926-860X(96)00253-0https://doi.org/10.1016/S0022-0728(71)80162-6https://doi.org/10.1016/S0022-0728(71)80162-6https://doi.org/10.1016/0022-0728(86)87051-6https://doi.org/10.1016/0022-0728(86)87051-6https://doi.org/10.1016/0022-0728(86)87051-6https://doi.org/10.1116/1.576378https://doi.org/10.1116/1.576378https://doi.org/10.1116/1.576378https://doi.org/10.1246/cl.2010.286https://doi.org/10.1246/cl.2010.286https://doi.org/10.1016/j.elecom.2016.03.015https://doi.org/10.1016/j.elecom.2016.03.015https://doi.org/10.1016/j.elecom.2016.03.015https://doi.org/10.1007/s12678-021-00699-yhttps://doi.org/10.1007/s12678-021-00699-yhttps://doi.org/10.1007/s12678-021-00699-yhttps://doi.org/10.1016/j.susc.2007.09.052https://doi.org/10.1016/j.susc.2007.09.052https://doi.org/10.1021/jp1024735?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp1024735?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1039/b821622nhttps://doi.org/10.1039/b821622nhttps://doi.org/10.1039/b821622nhttps://doi.org/10.1021/jp106593d?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp106593d?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp106593d?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1038/s41565-020-00824-whttps://doi.org/10.1038/s41565-020-00824-whttps://doi.org/10.1103/PhysRevLett.81.2819https://doi.org/10.1103/PhysRevLett.81.2819https://doi.org/10.1103/PhysRevLett.93.156801https://doi.org/10.1103/PhysRevLett.93.156801https://doi.org/10.1103/PhysRevLett.93.156801https://doi.org/10.1007/s11426-015-5324-yhttps://doi.org/10.1007/s11426-015-5324-yhttps://doi.org/10.1149/2.106204jeshttps://doi.org/10.1149/2.106204jeshttps://doi.org/10.1149/2.106204jeshttps://doi.org/10.1002/anie.201711858https://doi.org/10.1002/anie.201711858pubs.acs.org/JPCC?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c06652?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as(73) Zhang, X.; Yu, S.; Zheng, W.; Liu, P. Stability of Pt near surfacealloys under electrochemical conditions: a model study. Phys. Chem.Chem. Phys. 2014, 16 (31), 16615−16622.(74) van den Oetelaar, L. C. A.; Nooij, O. W.; Oerlemans, S.; Deniervan der Gon, A. W.; Brongersma, H. H.; Lefferts, L.; Roosenbrand, A.G.; van Veen, J. A. R. Surface Segregation in Supported Pd−PtNanoclusters and Alloys. J. Phys. Chem. B 1998, 102 (18), 3445−3455.(75) Duan, Z.; Wang, G. Monte Carlo simulation of surfacesegregation phenomena in extended and nanoparticle surfaces of Pt−Pd alloys. J. Phys.: Condens. Matter 2011, 23 (47), No. 475301.(76) Arenz, M.; Stamenkovic, V.; Schmidt, T. J.; Wandelt, K.; Ross,P. N.; Markovic, N. M. The electro-oxidation of formic acid on Pt−Pdsingle crystal bimetallic surfaces. Phys. Chem. Chem. Phys. 2003, 5(19), 4242−4251.(77) Zheng, Y.; Zhang, L.; He, P.; Dang, D.; Zeng, Q.; Zeng, J.; Liu,M. A Facile and Environmentally Friendly One-Pot Synthesis of PtSurface-Enriched Pt-Pd(x)/C Catalyst for Oxygen Reduction. Electro-catalysis 2018, 9 (4), 495−504.(78) Fantauzzi, M.; Atzei, D.; Elsener, B.; Lattanzi, P.; Rossi, A. XPSand XAES analysis of copper, arsenic and sulfur chemical state inenargites. Surf. Interface Anal. 2006, 38, 922.(79) Chen, K.; Xue, D. Reaction Route to the Crystallization ofCopper Oxides. Applied Science and Convergence Technology 2014, 23,14−26.(80) Seshadri, G.; Xu, H. C.; Kelber, J. A. Sulfur CatalyzedElectrochemical Oxidation of Copper: A Combined UltrahighVacuum Electrochemistry Study. J. Electrochem. Soc. 1999, 146 (5),1762.(81) Xu, H. C.; Seshadri, G.; Kelber, J. A. Effect of Sulfur on theOxidation of Copper in Aqueous Solution. J. Electrochem. Soc. 2000,147 (2), 558.(82) Jiang, H.; Yang, H.; Hawkins, R.; Ring, Z. Effect of palladiumon sulfur resistance in Pt−Pd bimetallic catalysts. Catal. Today 2007,125 (3), 282−290.(83) Stephens, I. E. L.; Bondarenko, A. S.; Perez-Alonso, F. J.; Calle-Vallejo, F.; Bech, L.; Johansson, T. P.; Jepsen, A. K.; Frydendal, R.;Knudsen, B. P.; Rossmeisl, J.; et al. Tuning the Activity of Pt(111) forOxygen Electroreduction by Subsurface Alloying. J. Am. Chem. Soc.2011, 133 (14), 5485−5491.(84) Wu, J.; Shan, S.; Cronk, H.; Chang, F.; Kareem, H.; Zhao, Y.;Luo, J.; Petkov, V.; Zhong, C. J. Understanding Composition-Dependent Synergy of PtPd Alloy Nanoparticles in ElectrocatalyticOxygen Reduction Reaction. J. Phys. Chem. C 2017, 121, 14128−14136.The Journal of Physical Chemistry C pubs.acs.org/JPCC Articlehttps://doi.org/10.1021/acs.jpcc.4c06652J. Phys. Chem. C 2025, 129, 2122−21312131https://doi.org/10.1039/C4CP01942Chttps://doi.org/10.1039/C4CP01942Chttps://doi.org/10.1021/jp973395q?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jp973395q?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1088/0953-8984/23/47/475301https://doi.org/10.1088/0953-8984/23/47/475301https://doi.org/10.1088/0953-8984/23/47/475301https://doi.org/10.1039/B306307Khttps://doi.org/10.1039/B306307Khttps://doi.org/10.1007/s12678-018-0466-2https://doi.org/10.1007/s12678-018-0466-2https://doi.org/10.1002/sia.2348https://doi.org/10.1002/sia.2348https://doi.org/10.1002/sia.2348https://doi.org/10.5757/ASCT.2014.23.1.14https://doi.org/10.5757/ASCT.2014.23.1.14https://doi.org/10.1149/1.1391839https://doi.org/10.1149/1.1391839https://doi.org/10.1149/1.1391839https://doi.org/10.1149/1.1393232https://doi.org/10.1149/1.1393232https://doi.org/10.1016/j.cattod.2006.11.026https://doi.org/10.1016/j.cattod.2006.11.026https://doi.org/10.1021/ja111690g?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/ja111690g?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acs.jpcc.7b03043?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acs.jpcc.7b03043?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acs.jpcc.7b03043?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-aspubs.acs.org/JPCC?ref=pdfhttps://doi.org/10.1021/acs.jpcc.4c06652?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://solutions.cas.org/CASInsights_Subscribe?utm_campaign=GLO_GEN_ANY_CIS_AWS&utm_medium=DSP_CAS_ORG&utm_source=Publication_CEN&utm_content=pdf_footer