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Ratschmeier B, Roß G, Kemna A, Braunschweig B. Influence of interfacial water and cations on the oxidation of CO at the platinum/ionic liquid interface. Phys Chem Chem Phys 2023; 25:1014-1022. [PMID: 36533703 DOI: 10.1039/d2cp05178h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
CO oxidation is fundamental to the development of new catalyst materials for fuel cells and key for complete oxidation of small alcohols like methanol or ethanol on Pt catalysts. So far, room-temperature ionic liquids (RTIL) have been used to modify the selectivity and activity in electrocatalysis. In order to understand the mechanism of CO oxidation in RTIL in more detail we have investigated this reaction at the Pt(111)/1-butyl-3-methylimidazolium trifluorosulfonylimide [BMIM][NTf2] electrode/electrolyte interface as a function of H2O concentration and electrode potential with in situ sum-frequency generation (SFG) spectroscopy and infrared absorption spectroscopy (IRAS). Using SFG spectroscopy, we address the changes of linearly bonded CO molecules on Pt(111), while we monitor the changes in the bulk electrolyte with IRAS through vibrational bands from H2O, CO2 and CO. The presence of water in [BMIM][NTf2] shifts the onset potential for CO oxidation by more than 200 mV when the water concentration is increased from 0.01 to 1.5 M, which we relate to the incorporation and the availability of water at the electrode/electrolyte interface. The nature of the RTIL cation has also a large effect on the surface excess of H2O since RTILs like [BMMIM][NTf2] and [BMPyrr][NTf2] which are prone to form closed-packed structures, can block the incorporation of water and lead to more sluggish CO oxidation with larger overpotentials and oxidation in a much wider potential range for which we provide evidence by additional SFG measurements. These results clearly show that the choice of the RTIL is important for CO oxidation on Pt(111) electrode surfaces - an observation that is likely highly relevant also to other catalysts and catalytic reactions that require the presence of interfacial water.
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Affiliation(s)
- Björn Ratschmeier
- Institute of Physical Chemistry, Westfälische Wilhelms University Münster, Corrensstraße 28/30, 48149, Münster, Germany.
| | - Gina Roß
- Institute of Physical Chemistry, Westfälische Wilhelms University Münster, Corrensstraße 28/30, 48149, Münster, Germany.
| | - Andre Kemna
- Institute of Physical Chemistry, Westfälische Wilhelms University Münster, Corrensstraße 28/30, 48149, Münster, Germany.
| | - Björn Braunschweig
- Institute of Physical Chemistry, Westfälische Wilhelms University Münster, Corrensstraße 28/30, 48149, Münster, Germany.
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2
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Noguchi H, Ishimaru T, Uosaki K. Potential and time dependent broad band sum frequency generation spectroscopic study on electrochemical oxidation of adsorbed CO on Pt(1 1 1) electrode surface in pre-peak region in alkaline solution. J Electroanal Chem (Lausanne) 2021. [DOI: 10.1016/j.jelechem.2021.115478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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3
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Ratschmeier B, Kemna A, Braunschweig B. Role of H
2
O for CO
2
Reduction Reactions at Platinum/Electrolyte Interfaces in Imidazolium Room‐Temperature Ionic Liquids. ChemElectroChem 2020. [DOI: 10.1002/celc.202000316] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Björn Ratschmeier
- Institute of Physical Chemistry Westfälische Wilhelms-Universität Münster Corrensstr. 28/30 48149 Münster Germany
| | - Andre Kemna
- Institute of Physical Chemistry Westfälische Wilhelms-Universität Münster Corrensstr. 28/30 48149 Münster Germany
| | - Björn Braunschweig
- Institute of Physical Chemistry Westfälische Wilhelms-Universität Münster Corrensstr. 28/30 48149 Münster Germany
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4
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Wei J, Amirbeigiarab R, Chen Y, Sakong S, Gross A, Magnussen OM. The Dynamic Nature of CO Adlayers on Pt(111) Electrodes. Angew Chem Int Ed Engl 2020; 59:6182-6186. [PMID: 31919982 PMCID: PMC7187359 DOI: 10.1002/anie.201913412] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Indexed: 11/10/2022]
Abstract
CO adlayers on Pt(111) electrode surfaces are an important electrochemical system and of great relevance to electrocatalysis. The potential-dependent structure and dynamics of these adlayers are complex and still controversial, especially in the CO pre-oxidation regime. We here employ in situ high-speed scanning tunneling microscopy for studying the surface phase behavior in CO-saturated 0.1 m H2 SO4 on the millisecond time scale. At potentials near the onset of CO pre-oxidation local fluctuations in the (2×2)-CO adlayer are observed, which increase towards more positive potentials. Above 0.20 V (vs. Ag/AgCl), this leads to an adlayer where COad apparently reside on every top site, but still exhibit a (2×2) superstructure modulation. We interpret this observation as a dynamic effect, caused by a small number of highly mobile point defects in the (2×2)-CO adlayer. As shown by density functional theory calculations, the CO lattice near such defects relaxes into a local (1×1) arrangement, which can rapidly propagate across the surface. This scenario, where a static (2×2) COad sublattice coexists with a highly dynamic sublattice of partially occupied top sites, explains the pronounced COad surface mobility during electrooxidation.
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Affiliation(s)
- Jie Wei
- Institute of Experimental and Applied PhysicsKiel University24098KielGermany
- Hefei National Laboratory for Physical Sciences at MicroscaleUniversity of Science and Technology of ChinaHefei230026China
| | | | - Yan‐Xia Chen
- Hefei National Laboratory for Physical Sciences at MicroscaleUniversity of Science and Technology of ChinaHefei230026China
| | - Sung Sakong
- Institute of Theoretical ChemistryUlm UniversityAlbert-Einstein-Allee 1189081UlmGermany
| | - Axel Gross
- Institute of Theoretical ChemistryUlm UniversityAlbert-Einstein-Allee 1189081UlmGermany
| | - Olaf M. Magnussen
- Institute of Experimental and Applied PhysicsKiel University24098KielGermany
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5
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Wei J, Amirbeigiarab R, Chen Y, Sakong S, Gross A, Magnussen OM. The Dynamic Nature of CO Adlayers on Pt(111) Electrodes. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201913412] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Jie Wei
- Institute of Experimental and Applied PhysicsKiel University 24098 Kiel Germany
- Hefei National Laboratory for Physical Sciences at MicroscaleUniversity of Science and Technology of China Hefei 230026 China
| | | | - Yan‐Xia Chen
- Hefei National Laboratory for Physical Sciences at MicroscaleUniversity of Science and Technology of China Hefei 230026 China
| | - Sung Sakong
- Institute of Theoretical ChemistryUlm University Albert-Einstein-Allee 11 89081 Ulm Germany
| | - Axel Gross
- Institute of Theoretical ChemistryUlm University Albert-Einstein-Allee 11 89081 Ulm Germany
| | - Olaf M. Magnussen
- Institute of Experimental and Applied PhysicsKiel University 24098 Kiel Germany
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Farias MJS, Busó-Rogero C, Tanaka AA, Herrero E, Feliu JM. Monitoring of CO Binding Sites on Stepped Pt Single Crystal Electrodes in Alkaline Solutions by in Situ FTIR Spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:704-714. [PMID: 31846345 DOI: 10.1021/acs.langmuir.9b02928] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The site geometry preference of CO binding on stepped Pt single crystals in alkaline solution was investigated by in situ FTIR spectroscopy. The surfaces of the Pt single crystals consisted of different width (111) terraces, interrupted by (110) or (100) monatomic steps. Experiments carried out with CO adsorbed exclusively on the top of the steps revealed that only linearly bonded CO formed on the (110) steps, while two CO binding geometries (linear and bridge) were observed on the (100) steps. On one hand, for CO adsorbed only on the steps, the positions of the bands corresponding to linearly bonded CO were similar, regardless of the density of steps, suggesting the existence of an interaction between COads only along the line of the steps. On the other hand, for full CO coverage, the CO stretching frequencies and the geometry of bound CO were sensitive to the width of the (111) terraces and the step orientations. Consequently, the CO binding sites favored linearly bonded CO for surfaces consisting of shorter (111) terraces and (110) steps. Bridge-bonded CO was favored on surfaces consisting of shorter (111) terraces interrupted by (100) steps. In order to understand the origin of the preference of CO binding sites, the results were compared to the corresponding behavior in acid media, which revealed that, in addition to the effect inherent to the Pt surface, the charge on the metal side in an aqueous environment should be taken into consideration. The analysis suggested that the CO adlayers formed at full coverage in acidic and alkaline media had different structures. On the other hand, the structure of the layer of CO adsorbed only at the steps was independent of pH.
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Affiliation(s)
- Manuel J S Farias
- Departamento de Química , Universidade Federal do Maranhão , Avenida dos Portugueses, 1966 , CEP 65080-805 São Luís , Maranhão , Brazil
| | - Carlos Busó-Rogero
- Instituto de Electroquímica , Universidad de Alicante , Ap. 99 , E-03080 Alicante , Spain
| | - Auro A Tanaka
- Departamento de Química , Universidade Federal do Maranhão , Avenida dos Portugueses, 1966 , CEP 65080-805 São Luís , Maranhão , Brazil
| | - Enrique Herrero
- Instituto de Electroquímica , Universidad de Alicante , Ap. 99 , E-03080 Alicante , Spain
| | - Juan M Feliu
- Instituto de Electroquímica , Universidad de Alicante , Ap. 99 , E-03080 Alicante , Spain
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7
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Kemna A, García Rey N, Braunschweig B. Mechanistic Insights on CO2 Reduction Reactions at Platinum/[BMIM][BF4] Interfaces from In Operando Spectroscopy. ACS Catal 2019. [DOI: 10.1021/acscatal.9b01033] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Andre Kemna
- Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
| | - Natalia García Rey
- Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
| | - Björn Braunschweig
- Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
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Gardner AM, Saeed KH, Cowan AJ. Vibrational sum-frequency generation spectroscopy of electrode surfaces: studying the mechanisms of sustainable fuel generation and utilisation. Phys Chem Chem Phys 2019; 21:12067-12086. [DOI: 10.1039/c9cp02225b] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The electrocatalytic oxidation of water coupled to the reduction of carbon dioxide, to make carbon based products, or the reduction of protons to provide hydrogen, offers a sustainable route to generating useful fuels.
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Affiliation(s)
- Adrian M. Gardner
- Stephenson Institute for Renewable Energy and the Department of Chemistry
- University of Liverpool
- Liverpool
- UK
| | - Khezar H. Saeed
- Stephenson Institute for Renewable Energy and the Department of Chemistry
- University of Liverpool
- Liverpool
- UK
| | - Alexander J. Cowan
- Stephenson Institute for Renewable Energy and the Department of Chemistry
- University of Liverpool
- Liverpool
- UK
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9
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García Rey N, Dlott DD. Effects of water on low-overpotential CO 2 reduction in ionic liquid studied by sum-frequency generation spectroscopy. Phys Chem Chem Phys 2018; 19:10491-10501. [PMID: 28383582 DOI: 10.1039/c7cp00118e] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We used vibrational sum-frequency generation spectroscopy (SFG) to investigate low-overpotential CO2 reduction on a polycrystalline Ag electrode using room temperature ionic liquid (RTIL), 1-ethyl-3-methylimidazolium tetrafluorborate (EMIM-BF4) electrolyte mixtures with 0.3 mol%, 45 mol% and 77 mol% water. Adding water dramatically increases CO2 reduction efficiency up to 87.5 mol%. We found added water reduces the (negative) threshold potential for CO2 reduction from -1.33 V to -0.9 V. Added water also moved the potentials of the nonresonant (NR) SFG minima and caused the CO Stark shift to increase in concert with the reduction threshold. In previous work (N. García Rey and D. D. Dlott, J. Phys. Chem. C, 2015, 119, 20892-20899), with nearly-dry RTIL electrolyte (0.3 mol% water), we concluded a potential-driven structural transition of RTIL in the double layer controlled CO2 reduction. At lower water concentrations, where CO2 reduction was less efficient, CO product appeared primarily on Ag atop sites. At higher water concentrations where CO2 reduction efficiency was greater, adsorbed CO was observed on multiply-bonded sites, which are likely more efficient catalytic sites.
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Affiliation(s)
- Natalia García Rey
- School of Chemical Sciences and Fredrick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Il 61801, USA.
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10
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Rey NG, Dlott DD. Studies of electrochemical interfaces by broadband sum frequency generation. J Electroanal Chem (Lausanne) 2017. [DOI: 10.1016/j.jelechem.2016.12.023] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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11
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Electrochemical Kinetics: a Surface Science-Supported Picture of Hydrogen Electrochemistry on Ru(0001) and Pt/Ru(0001). Electrocatalysis (N Y) 2017. [DOI: 10.1007/s12678-017-0381-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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12
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Yang S, Noguchi H, Uosaki K. Broader energy distribution of CO adsorbed at polycrystalline Pt electrode in comparison with that at Pt(111) electrode in H2SO4 solution confirmed by potential dependent IR/visible double resonance sum frequency generation spectroscopy. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.03.113] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Kraack JP, Hamm P. Surface-Sensitive and Surface-Specific Ultrafast Two-Dimensional Vibrational Spectroscopy. Chem Rev 2016; 117:10623-10664. [DOI: 10.1021/acs.chemrev.6b00437] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Jan Philip Kraack
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Peter Hamm
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
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14
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Jebaraj AJJ, Scherson D. Quantitative aspects of normalized differential reflectance spectroscopy: Pt(111) in aqueous electrolytes. Anal Chem 2014; 86:4241-8. [PMID: 24702156 DOI: 10.1021/ac403895z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
A theoretical model is herein proposed to account for changes in the normalized differential reflectance, ΔR/R, of well-defined single crystal Pt(111) surfaces|aqueous electrolyte interfaces. It assumes that ΔR/R is proportional to the area of the electrode either bare or covered by neutral and/or nominally charged species and, for a specific type of site, is modulated by the applied potential, E. Correlations between the coverage of the various species and E were obtained from data reported in the literature or by coulometric analysis of linear voltammetric scans. Excellent agreement was found for the adsorption/desorption of hydrogen and that of bisulfate from acidic electrolytes both on bare, and cyanide-modified Pt(111). Also discussed are extensions of this technique in the transient mode involving the reduction of adsorbed nitric oxide, NO, on Pt(111).
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15
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Chemisorbed Molecules under Potential Bias: Detailed Insights from First-Principles Vibrational Spectroscopies. Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2013.12.115] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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16
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Surface spectroscopy of Pt(1 1 1) single-crystal electrolyte interfaces with broadband sum-frequency generation. J Electroanal Chem (Lausanne) 2014. [DOI: 10.1016/j.jelechem.2013.10.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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17
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18
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Gilman S. Study of acetate adsorption at the platinum electrode/acid electrolyte interface using “blocking effects”: Influences of acetate adsorption on ethanol fuel cell electrodes. Electrochim Acta 2012. [DOI: 10.1016/j.electacta.2012.01.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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20
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Kim J, Kim S, Rhee CK. Preoxidation of CO on Os-modified Pt(111): a comparison with Ru-modified Pt(111). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:2044-2051. [PMID: 21244079 DOI: 10.1021/la103256k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The variation in CO adsorption structures during the preoxidation of CO on Os-modified Pt(111) (Pt(111)/Os) was investigated using cyclic voltammetry and electrochemical scanning tunneling microscopy. The spontaneous deposition of Os on Pt(111) resulted in randomly scattered islands with a coverage range of 0.13-0.54. During preoxidation on Pt(111)/Os, a phase transition from (2 × 2)-α to (√19 × √19) via the transient structures of (2 × 2)-β and (1 × 1) took place as on unmodified Pt(111). As the amount of Os increased, however, the transient structures of (2 × 2)-β and (1 × 1) appeared at lower potentials with higher populations. When the population of the transient structures was greater than 50%, an oxidative CO stripping process took place to the structure of (√19 × √19), completing the preoxidation. These observations strongly support the idea that the presence of Os increases the mobility of adsorbed CO by electronic modification of the Pt(111) surface (electronic effect). In addition, the results obtained with Pt(111)/Os were compared with those of Pt(111)/Ru.
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Affiliation(s)
- Jandee Kim
- Department of Chemistry, Chungnam National University, Dajeon 305-764, South Korea
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21
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Shaw SK, Berná A, Feliu JM, Nichols RJ, Jacob T, Schiffrin DJ. Role of axially coordinated surface sites for electrochemically controlled carbon monoxide adsorption on single crystal copper electrodes. Phys Chem Chem Phys 2011; 13:5242-51. [DOI: 10.1039/c0cp02064h] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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22
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Braunschweig B, Mukherjee P, Kutz RB, Wieckowski A, Dlott DD. Sum-frequency generation of acetate adsorption on Au and Pt surfaces: Molecular structure effects. J Chem Phys 2010; 133:234702. [DOI: 10.1063/1.3507257] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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23
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Broad-band sum frequency generation study of formic acid chemisorption on a Pt (100) electrode. J Electroanal Chem (Lausanne) 2010. [DOI: 10.1016/j.jelechem.2009.12.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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24
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Lagutchev A, Lozano A, Mukherjee P, Hambir SA, Dlott DD. Compact broadband vibrational sum-frequency generation spectrometer with nonresonant suppression. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2010; 75:1289-1296. [PMID: 20129816 DOI: 10.1016/j.saa.2009.12.066] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 12/22/2009] [Accepted: 12/24/2009] [Indexed: 05/28/2023]
Abstract
A compact broadband vibrational sum-frequency spectroscopy (SFG) apparatus is described to study molecules at surfaces and interfaces. Using an étalon as the frequency narrowing device, the visible pulse has a time-asymmetric profile that allows the user to deeply suppress nonresonant background signals that hinder detection of molecular vibrational resonances. Several features of the spectrometer that, in aggregate, improve signal-to-noise ratios by a large factor are described. The spectrometer features a series of interchangeable prealigned sample holders for different applications. Examples of applications are presented where nonresonant suppression greatly improves the ability to study adsorbates on single-crystal surfaces as a function of rotation about the azimuth, and where the rapid data acquisition abilities of the spectrometer are used to study electrochemical transformations on single-crystal electrodes.
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Affiliation(s)
- Alexei Lagutchev
- School of Chemical Sciences, University of Illinois at Urbana Champaign, Urbana, IL 61801, USA
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25
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Analysis of the electrochemical quartz crystal microbalance response during oxidation of carbon oxides adsorption products on platinum group metals and alloys. J Solid State Electrochem 2009. [DOI: 10.1007/s10008-009-0926-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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26
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Carter JA, Wang Z, Dlott DD. Ultrafast nonlinear coherent vibrational sum-frequency spectroscopy methods to study thermal conductance of molecules at interfaces. Acc Chem Res 2009; 42:1343-51. [PMID: 19388671 DOI: 10.1021/ar9000197] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
It is difficult to study molecules at surfaces or interfaces because the total number of molecules is small, and this is especially problematic in studies of interfacial molecular dynamics with high time resolution. Vibrational sum-frequency generation (SFG) spectroscopy, where infrared (IR) and visible pulses are combined at an interface, has emerged as a powerful method to probe interfacial molecular dynamics. The nonlinear coherent nature of SFG helps overcome the sensitivity issues, especially when femtosecond IR pulses are used. With femtosecond pulses, a range of vibrational transitions can be probed simultaneously and high time resolution can be achieved. Ultrafast SFG experiments use three pulses, a pump pulse to generate nonequilibrium conditions with a pair of probe pulses, and two time delay parameters. Mapping SFG intensity as a function of the two time delays creates a two-dimensional surface, where one axis (t(1)) provides information about molecular dynamics driven by the pump pulses, and the other axis (t(2)) about the dynamics of the SFG probing process. We present examples of ultrafast SFG measurements drawn from our studies of heat transport through interfacial molecules that are models for molecular wires in electronic circuits. In these flash-heating experiments, a self-assembled monolayer (SAM) of long-chain molecules adsorbed on a metal surface is subjected to a large amplitude (up to 800 K) temperature jump. Specific vibrational reporter groups on the SAM molecules probed by SFG serve as tiny ultrafast thermometers approximately 1.5 A thick with a approximately 1 ps response time. These SFG thermometers can monitor ultrafast heat transport through the SAM molecules. By varying the lengths of the molecular wires we can tell if the heat is propagating ballistically along the chains, at constant speed, or diffusively. In our analysis of 2D SFG methods, we first describe a simpler situation where the visible probe pulse is effectively infinite in duration. This is the usual way time-resolved SFG measurements are made, and the SFG experiment then becomes a function of a single time delay, the pump-IR probe delay t(1). Unfortunately, in this case the SFG signals have a large contribution from the nonresonant (NR) background generated by the metal surface, which adds a great deal of noise to the data, and the time resolution is limited by the molecule's vibrational dephasing time constant T(2), which is often 1 ps or more. We have recently shown that the NR background can be suppressed using a time delay t(2) between IR and visible probe pulses. In this now 2D SFG method, one would expect that information about the molecular response to the pump pulses would be contained in slices along the t(1) axis, but by simulating the experiment we show that the t(1) and t(2) parameters interact. Changing t(2) to suppress the NR background causes t(1) slices to shift in time. We also show how to improve the time resolution of ultrafast SFG experiments while maintaining NR suppression using femtosecond visible pulses at appropriate t(2) delay values.
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Affiliation(s)
- Jeffrey A. Carter
- School of Chemical Sciences, University of Illinois at Urbana−Champaign, Chemical and Life Sciences Laboratory, 600 South Mathews Avenue, Urbana, Illinois 61801
| | - Zhaohui Wang
- School of Chemical Sciences, University of Illinois at Urbana−Champaign, Chemical and Life Sciences Laboratory, 600 South Mathews Avenue, Urbana, Illinois 61801
| | - Dana D. Dlott
- School of Chemical Sciences, University of Illinois at Urbana−Champaign, Chemical and Life Sciences Laboratory, 600 South Mathews Avenue, Urbana, Illinois 61801
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27
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Fromondi I, Scherson D. Surface dynamics at well-defined single crystal microfacetted Pt(111) electrodes: in situ optical studies. Faraday Discuss 2009; 140:59-68; discussion 93-112. [DOI: 10.1039/b805040f] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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28
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Shaw SK, Lagutchev A, Dlott DD, Gewirth AA. Sum-Frequency Spectroscopy of Molecular Adsorbates on Low-Index Ag Surfaces: Effects of Azimuthal Rotation. Anal Chem 2008; 81:1154-61. [DOI: 10.1021/ac802332h] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Scott K. Shaw
- School of Chemical Sciences, University of Illinois, 600 S. Mathews Avenue, Urbana, Illinois 61801
| | - Alexei Lagutchev
- School of Chemical Sciences, University of Illinois, 600 S. Mathews Avenue, Urbana, Illinois 61801
| | - Dana D. Dlott
- School of Chemical Sciences, University of Illinois, 600 S. Mathews Avenue, Urbana, Illinois 61801
| | - Andrew A. Gewirth
- School of Chemical Sciences, University of Illinois, 600 S. Mathews Avenue, Urbana, Illinois 61801
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Gao W, Zhao M, Jiang Q. Pathways for the Non-CO-Involved Oxidation of Methanol on Pt(111). Chemphyschem 2008; 9:2092-8. [DOI: 10.1002/cphc.200800150] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Noguchi H, Hiroshi M, Tominaga T, Gong JP, Osada Y, Uosaki K. Interfacial water structure at polymer gel/quartz interfaces investigated by sum frequency generation spectroscopy. Phys Chem Chem Phys 2008; 10:4987-93. [PMID: 18688544 DOI: 10.1039/b807297n] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Interfacial structures of water at polyvinyl alcohol (PVA) and poly(2-acrylamido-2-methypropane) sulfonic acid sodium salt (PNaAMPS)/quartz interfaces were investigated by sum frequency generation (SFG) spectroscopy. Two broad peaks were observed in OH stretching region at 3200 and 3400 cm(-1), corresponding to the symmetric OH stretching of tetrahedrally coordinated, i.e., strongly hydrogen bonded "ice-like" water, and the asymmetric OH stretching of water in a more random arrangement, i.e., weakly hydrogen bonded "liquid-like" water, respectively, in both cases. The "liquid-like" water became dominant when the PVA gel was pressed against the quartz surface. The relative intensity of the SFG signal due to the "liquid-like" water to that due to the "ice-like water" at the quartz surface modified with a self-assembled monolayer of aminopropyltrimethoxysilane (APS) became higher when the negatively charged PNaMPS gel was contacted to the APS modified quartz surface in a solution of pH = 12, where the surface was negatively charged and electrostatic repulsive interaction and low friction were present between the PNaMPS gel and the APS modified surface. It, however, did not change in a solution of pH = 2, where the surface was positively charged and electrostatic attractive interaction and very high friction were present between the PNaMPS gel and the APS modified surface. These results suggest the important role of water structure for small friction at the polymer gel/solid interface.
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Affiliation(s)
- Hidenori Noguchi
- Physical Chemistry Laboratory, Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
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Łukaszewski M, Siwek H, Czerwiński A. Electrosorption of carbon dioxide on platinum group metals and alloys—a review. J Solid State Electrochem 2008. [DOI: 10.1007/s10008-008-0618-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Siwek H, Łukaszewski M, Czerwiński A. Electrochemical study on the adsorption of carbon oxides and oxidation of their adsorption products on platinum group metals and alloys. Phys Chem Chem Phys 2008; 10:3752-65. [DOI: 10.1039/b718286b] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Jung C, Kim J, Rhee CK. Electrochemical scanning tunneling microscopic observation of the preoxidation process of CO on Pt(111) electrode surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:9495-500. [PMID: 17650016 DOI: 10.1021/la701103u] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Presented are sequential images of CO on Pt(111), observed with electrochemical scanning tunneling microscopy, during its electrochemical preoxidation process. In the course of the well-known phase transition from the (2 x 2)-3CO-alpha structure to the (radical 19 x radical 19)R23.4 degrees-13CO structure, various structures were observed: (2 x 2)-3CO-beta (Chem. Comm. 2006, 2191-2193), (1 x 1)-CO, and (radical 13 x radical 13)R46.1 degrees-9CO. Based on an analysis of the populations of the structures averaged over imaging time and imaged location at the preoxidation potential range (0-0.25 V vs Ag/AgCl), the structures of CO domains changed sequentially in the order of (2 x 2)-3CO-alpha, (2 x 2)-3CO-beta, (1 x 1)-CO, (radical 13 x radical 13)R46.1 degrees-9CO, and (radical 19 x radical 19)R23.4 degrees-13CO as the potential shifted from 0 to 0.25 V. Such a sequential structural change demonstrates that the structures of (2 x 2)-3CO-beta, (1 x 1)-CO, and (radical 13 x radical 13)R46.1 degrees-9CO are transient ones during the preoxidation of CO on Pt(111). Discussed are the transient structures in terms of various aspects, such as the absence of CO in solution and the origin of compressed structures.
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Affiliation(s)
- Changhoon Jung
- Department of Chemistry, Chungnam National University, Daejeon, South Korea
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Skúlason E, Karlberg GS, Rossmeisl J, Bligaard T, Greeley J, Jónsson H, Nørskov JK. Density functional theory calculations for the hydrogen evolution reaction in an electrochemical double layer on the Pt(111) electrode. Phys Chem Chem Phys 2007; 9:3241-50. [PMID: 17579732 DOI: 10.1039/b700099e] [Citation(s) in RCA: 373] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present results of density functional theory calculations on a Pt(111) slab with a bilayer of water, solvated protons in the water layer, and excess electrons in the metal surface. In this way we model the electrochemical double layer at a platinum electrode. By varying the number of protons/electrons in the double layer we investigate the system as a function of the electrode potential. We study the elementary processes involved in the hydrogen evolution reaction, 2(H(+) + e(-)) --> H(2), and determine the activation energy and predominant reaction mechanism as a function of electrode potential. We confirm by explicit calculations the notion that the variation of the activation barrier with potential can be viewed as a manifestation of the Brønsted-Evans-Polanyi-type relationship between activation energy and reaction energy found throughout surface chemistry.
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Affiliation(s)
- Egill Skúlason
- Center for Atomic-scale Materials Design, Department of Physics, Building 307, NanoDTU, Technical University of Denmark, DK-2800, Lyngby, Denmark
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