Structure and composition of a platinum(111) surface as a function of pH and electrode potential in aqueous bromide solutions

Salaita, Ghaleb N.; Stern, Donald A.; Lu, Frank K.; Baltruschat, Helmut; Schardt, Bruce C.; Stickney, John L.; Soriaga, Manuel P.; Frank, Douglas G.; Hubbard, Arthur T.

doi:10.1021/la00072a031

Cited by 76 publications

(63 citation statements)

References 3 publications

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“…However, the STM images obtained at potentials lower than the sharp spike revealed that the Br adlayer was not the (4 · 4) structure proposed in Ref. [9], but an incommensurate structure. Independently, Orts et al studied the properties of strongly adsorbed bromine monolayers formed either by bromide or by bromine adsorption on a Pt(1 1 1) surface, using cyclic voltammetry, CO charge-displacement method and ex situ STM imaging [11].…”

Section: Introductionmentioning

confidence: 53%

“…First, we used 0.1 M HClO 4 as the supporting electrolyte. In these solutions, the substitution of hydrogen by bromide at the Pt(1 1 1) surface takes place in a very narrow potential range, as described previously [6][7][8][9][10][11]. The corresponding voltammetric peaks are very sharp, and the integration of such curves is subjected to a non-negligible error.…”

Section: Introductionmentioning

confidence: 96%

“…Their experiments involved transfer of the sample from the electrochemical cell to UHV, where Auger spectroscopy and LEED were used to characterize the adlayers [8,9]. The structural information extracted from these studies was used for the interpretation of the characteristic features observed on a cyclic voltammogram (CV).…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamic studies of bromide adsorption at the Pt(111) electrode surface perchloric acid solutions: Comparison with other anions

Garcı́a-Aráez

Climent

Herrero

et al. 2006

Journal of Electroanalytical Chemistry

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Section: Introductionmentioning

confidence: 53%

Section: Introductionmentioning

confidence: 96%

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Thermodynamic studies of bromide adsorption at the Pt(111) electrode surface perchloric acid solutions: Comparison with other anions

Garcı́a-Aráez

Climent

Herrero

et al. 2006

Journal of Electroanalytical Chemistry

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“…This trend is in accordance with the shift observed in case of single crystal electrode. 33,35 Figs. 4d, 4e and 4f show the CVs of Pt-NC, Pt-CO and Pt-PC, respectively, recorded with 1 × 10 −3 M Br − ions in the potential range of 0.06-1.2, 1.4, 1.6 V. The Pt oxidation and reduction features of the CVs are suppressed when compared to that observed with halide-free electrolyte (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…[10][11][12][13][14][15][16][17][18][19][20][21] Feliu et al, Abruna et al, and others have extensively investigated the influence of halides (I − , Br − , Cl − ) on platinum single crystal electrodes. [22][23][24][25][26][27][28][29][30][31][32][33][34][35] Most of the available surface sensitive techniques were used to elucidate adsorbate coverage and structure. Such techniques, including auger electron spectroscopy (AES), low energy electron diffraction (LEED), second harmonic generation (SHG), surface X-ray scattering (SXS), electrochemical scanning tunneling microscope (ESTM) 31,34 and electrochemical quartz crystal microbalance (EQCM), used to investigate anion adsorption have offered significant insight on the dependence of adsorption process on exposed single crystal orientations.…”

mentioning

confidence: 99%

Recovery of Active Surface Sites of Shape-Controlled Platinum Nanoparticles Contaminated with Halide Ions and Its Effect on Surface-Structure

Devivaraprasad¹,

Kar²,

Leuaa³

et al. 2017

J. Electrochem. Soc.

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The interaction of halide ions (I − , Br − , Cl − ) with well-cleaned faceted platinum (nanocube, cuboctahedral) nanoparticles and platinum polycrystalline is investigated in 0.5 M H 2 SO 4 electrolyte. Under electrochemical conditions, the Pt surface gets poisoned with halide ad-atoms and it causes the attenuation of both hydrogen adsorption/desorption in the lower potential region (0.06-0.4 V) and electroxidation of Pt nanoparticles in the higher potential region (0.6-1.2 V). Above certain concentration (5 × 10 −6 M), the strongly adsorbing I − ions mask the H upd features. On the other hand, Br − and Cl − ions alter the peak features in the H upd region, those are characteristic of different Pt surface sites. On excursion to higher potentials (∼>1.2 V), concurrent halogen evolution, Pt oxidation, and oxygen evolution are observed; the increase in peak intensity in the H upd region reflects the reconstruction of the Pt surface. To remove the adsorbed halide ions from the Pt surface, an in-situ potentiostatic method is employed, which involves holding the working electrode at ∼0.03 V in 0.1 M NaOH solution. The cleanliness and retention of surface-structure are confirmed from the voltammograms recorded in the test electrolyte and the recovery of oxygen reduction reaction (ORR) activity after cleaning the Br − ion-contaminated Pt surface supports this conjecture. Anions specifically adsorbed on precious metal surfaces adversely impact several electrochemical reactions including oxidation/ reduction, metal deposition, corrosion and dissolution.1-6 Catalyst poisoning by the adsorbed anions (halides, sulfates and others) is a well-known phenomenon and it decreases the activity of electrocatalysts; for example, in fuel-cell, batteries and electrolyzers. 7,8 Especially platinum, a material for catalyzing a variety of electrochemical reactions, is prone to get poisoned in the presence of adatoms/adsorbates/solution anions under electrochemical conditions. Thus, oxygen reduction reaction (ORR) in fuel cells is affected by the adsorbed species or impurities and it is highly dependent on the cleanliness and surface structure of the catalyst. [9][10][11][12][13] In hydrogen-bromine fuel cells, bromides and bromine species migrate across the membrane and poison the hydrogen-electrode catalyst; moreover, Pt dissolves in Br − ion-containing solutions. 22-35 Most of the available surface sensitive techniques were used to elucidate adsorbate coverage and structure. Such techniques, including auger electron spectroscopy (AES), low energy electron diffraction (LEED), second harmonic generation (SHG), surface X-ray scattering (SXS), electrochemical scanning tunneling microscope (ESTM) 31,34 and electrochemical quartz crystal microbalance (EQCM), used to investigate anion adsorption have offered significant insight on the dependence of adsorption process on exposed single crystal orientations. Thus, AES/LEED studies revealed that Cl − ion adsorption occurs on Pt(100) surface at lower potential than that with Pt(111) surfaces, indi...

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Surface Analysis for Electrochemistry: Ultrahigh Vacuum Techniques

Soriaga

2000

Encyclopedia of Analytical Chemistry

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The study of processes that transpire at heterogeneous interfaces is an exceedingly difficult proposition. No single experimental technique can ever hope to unravel all the nuances of heterogeneous reactions; hence, in surface science, the use of multiple complementary methods is not uncommon. Ultrahigh vacuum electrochemistry (UHV/EC) is a term ascribed to the approach that rests upon the integration of classical electrochemical methods with surface‐sensitive analytical techniques; this strategy parallels that successfully implemented in the study of gas–solid heterogeneous catalysis. The unique surface sensitivity of the techniques adopted emanates from the use of particles (e.g. ions or electrons) that serve to interrogate the outermost layer(s) of the electrode. This surface sensitivity is tempered by the requirement that the analysis be performed in an environment (outside the electrochemical cell) that does not impede the mean‐free paths of the probe particles. Since its inception in the early 1970s, more than a thousand UHV/EC‐based studies have been published; most of the work involved polycrystalline materials and focused on the elemental composition at the electrode surface. While its importance in the study of polycrystalline surfaces cannot be trivialized, the greater value of UHV/EC appears to be in its ability to help resolve fundamental issues that intertwine interfacial structure and composition with electrochemical reactivity. It is in this context that the present review is written. A complete mechanism of an electrochemical reaction must incorporate all the physical and chemical interactions that arise between an electrified surface and its environment. The extent of such interactions depends upon several factors such as solvent, supporting electrolyte, electrode potential, reactant concentration, electrode material and surface crystallographic orientation. The traditional approach is based upon a thermodynamic treatment of the interface and its response to external perturbations. Interpretation of the results relies on phenomenological models of the interface. Although a thermodynamic treatment cannot be ignored, the need for an atomic‐level view has long been realized. One approach1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 towards the establishment of an atomic‐level description parallels that successfully implemented in the study of gas–solid heterogeneous catalysis; it rests upon the integration of classical electrochemical methods with surface‐sensitive analytical techniques. The analytical methods that exhibit surface sensitivity are based upon the mass‐selection and/or energy‐discrimination of electrons, ions, atoms or molecules scattered from solid surfaces. These particles have shallow escape depths; hence the information they bear is characteristic of the near‐surface layers. Their short mean‐free paths, however, necessitate a high vacuum (<10 −6 torr) environment. The application of such surface techniques to electrochemistry requires that the analysis be performed outside the electrochemical cell. The possibility of structural and compositional changes that accompany the removal of the electrode from solution is the major concern in UHV/EC studies. Although a myriad of surface analytical techniques is currently available, those actually employed in UHV/EC have been limited to low‐energy electron diffraction (LEED), Auger electron spectroscopy (AES), X‐ray photoelectron spectroscopy (XPS), high‐resolution electron energy loss spectroscopy (HREELS), reflection high‐energy electron diffraction (RHEED), work‐function changes, and thermal desorption mass spectrometry (TDMS). While most vacuum‐based analytical methods do not require single‐crystal surfaces, the use of uniform (monocrystalline) surfaces is a necessary aspect for fundamental studies. The low‐index crystallographic faces [(100), (110) and (111)] have been widely used because of their low free energies, high symmetries, and relative stabilities. In addition, it may be possible to reconstruct the overall behavior of polycrystalline electrodes from the individual properties of the low‐index planes. 1, 2, 3, 4 A handful of procedures for the preparation and preservation of well‐defined single‐crystal surfaces have been described. 5, 6, 7, 8 The verification or identification of initial, intermediate, and final interfacial structures and compositions is an essential ingredient in electrochemical surface science.

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Structure and composition of a platinum(111) surface as a function of pH and electrode potential in aqueous bromide solutions

Cited by 76 publications

References 3 publications

Thermodynamic studies of bromide adsorption at the Pt(111) electrode surface perchloric acid solutions: Comparison with other anions

Thermodynamic studies of bromide adsorption at the Pt(111) electrode surface perchloric acid solutions: Comparison with other anions

Recovery of Active Surface Sites of Shape-Controlled Platinum Nanoparticles Contaminated with Halide Ions and Its Effect on Surface-Structure

Surface Analysis for Electrochemistry: Ultrahigh Vacuum Techniques

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