1
|
Youden B, Yang D, Carrier A, Oakes K, Servos M, Jiang R, Zhang X. Speciation Analysis of Metals and Metalloids by Surface Enhanced Raman Spectroscopy. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024. [PMID: 39250346 DOI: 10.1021/acs.est.4c06906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/11/2024]
Abstract
The presence of metalloids and heavy metals in the environment is of critical concern due to their toxicological impacts. However, not all metallic species have the same risk level. Specifically, the physical, chemical, and isotopic speciation of the metal(loids) dictate their metabolism, toxicity, and environmental fate. As such, speciation analysis is critical for environmental monitoring and risk assessment. In the past two decades, surface-enhanced Raman spectroscopy (SERS) has seen significant developments regarding trace metal(loid) sensing due to its ultrahigh sensitivity, readiness for in situ real-time applications, and cost-effectiveness. However, the speciation of metal(loid)s has not been accounted for in the design and application of SERS sensors. In this Perspective, we examine the potential of SERS for metal(loid) speciation analysis and highlight the advantages, progress, opportunities, and challenges of this application.
Collapse
Affiliation(s)
- Brian Youden
- Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Dongchang Yang
- Department of Chemistry, Cape Breton University, Sydney, Nova Scotia B1P 6L2, Canada
| | - Andrew Carrier
- Department of Chemistry, Cape Breton University, Sydney, Nova Scotia B1P 6L2, Canada
| | - Ken Oakes
- Department of Biology, Cape Breton University, Sydney, Nova Scotia B1P 6L2, Canada
| | - Mark Servos
- Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Runqing Jiang
- Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
- Department of Medical Physics, Grand River Regional Cancer Centre, Kitchener, Ontario N2G 1G3, Canada
| | - Xu Zhang
- Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
- Department of Chemistry, Cape Breton University, Sydney, Nova Scotia B1P 6L2, Canada
| |
Collapse
|
2
|
Sun YL, Ji X, Wang X, He QF, Dong JC, Le JB, Li JF. Visualization of Electrooxidation on Palladium Single Crystal Surfaces via In Situ Raman Spectroscopy. Angew Chem Int Ed Engl 2024:e202408736. [PMID: 39107260 DOI: 10.1002/anie.202408736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Revised: 07/14/2024] [Accepted: 08/06/2024] [Indexed: 08/09/2024]
Abstract
The electrooxidation of catalyst surfaces is across various electrocatalytic reactions, directly impacting their activity, stability and selectivity. Precisely characterizing the electrooxidation on well-defined surfaces is essential to understanding electrocatalytic reactions comprehensively. Herein, we employed in situ Raman spectroscopy to monitor the electrooxidation process of palladium single crystal. Our findings reveal that the Pd surface's initial electrooxidation process involves forming *OH intermediate and ClO4 - ions facilitate the deprotonation process, leading to the formation of PdOx. Subsequently, under deep electrooxidation potential range, the oxygen atoms within PdOx contribute to creating surface-bound peroxide species, ultimately resulting in oxygen generation. The adsorption strength of *OH and the coverage of ClO4 - can be adjusted by the controllable electronic effect, resulting in different oxidation rates. This study offers valuable insights into elucidating the electrooxidation mechanisms underlying a range of electrocatalytic reactions, thereby contributing to the rational design of catalysts.
Collapse
Affiliation(s)
- Yu-Lin Sun
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, College of Energy, College of Materials, Xiamen University, 361005, Xiamen, China
| | - Xu Ji
- Key Laboratory of Advanced Fuel Cells and Electrolyzers Technology of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Key Laboratory of Advanced Marine Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, 315201, Ningbo, China
| | - Xue Wang
- Key Laboratory of Advanced Fuel Cells and Electrolyzers Technology of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Key Laboratory of Advanced Marine Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, 315201, Ningbo, China
| | - Quan-Feng He
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, College of Energy, College of Materials, Xiamen University, 361005, Xiamen, China
| | - Jin-Chao Dong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, College of Energy, College of Materials, Xiamen University, 361005, Xiamen, China
| | - Jia-Bo Le
- Key Laboratory of Advanced Fuel Cells and Electrolyzers Technology of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Key Laboratory of Advanced Marine Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, 315201, Ningbo, China
| | - Jian-Feng Li
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, College of Energy, College of Materials, Xiamen University, 361005, Xiamen, China
| |
Collapse
|
3
|
Clark CA, Reddy CP, Xu H, Heck KN, Luo G, Senftle TP, Wong MS. Mechanistic Insights into pH-Controlled Nitrite Reduction to Ammonia and Hydrazine over Rhodium. ACS Catal 2019. [DOI: 10.1021/acscatal.9b03239] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
| | | | - Hao Xu
- Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | | | - Guohua Luo
- Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | | | | |
Collapse
|
4
|
Almeida NMS, Ariyarathna IR, Miliordos E. Ab initio calculations on the ground and excited electronic states of neutral and charged palladium monoxide, PdO0,+,−. Phys Chem Chem Phys 2018; 20:14578-14586. [DOI: 10.1039/c8cp01251b] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Multi-reference configuration interaction and coupled cluster calculations were carried out for the ground and several low-lying excited electronic states for PdO, PdO+, and PdO−. The photoelectron spectrum peaks of PdO were assigned.
Collapse
|
5
|
Infrared spectroscopy of adsorbed OH on n(111)–(100) and n(111)–(111) series of Pt electrode. J Electroanal Chem (Lausanne) 2017. [DOI: 10.1016/j.jelechem.2016.11.028] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
6
|
Ledezma-Yanez I, Díaz-Morales O, Figueiredo MC, Koper MTM. Hydrogen Oxidation and Hydrogen Evolution on a Platinum Electrode in Acetonitrile. ChemElectroChem 2015. [DOI: 10.1002/celc.201500341] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Isis Ledezma-Yanez
- Leiden Institute of Chemistry; Leiden University; PO Box 9502 2300 RA Leiden The Netherlands
| | - Oscar Díaz-Morales
- Leiden Institute of Chemistry; Leiden University; PO Box 9502 2300 RA Leiden The Netherlands
| | - Marta C. Figueiredo
- Leiden Institute of Chemistry; Leiden University; PO Box 9502 2300 RA Leiden The Netherlands
| | - Marc T. M. Koper
- Leiden Institute of Chemistry; Leiden University; PO Box 9502 2300 RA Leiden The Netherlands
| |
Collapse
|
7
|
Harvey CE, Weckhuysen BM. Surface- and Tip-Enhanced Raman Spectroscopy as Operando Probes for Monitoring and Understanding Heterogeneous Catalysis. Catal Letters 2014; 145:40-57. [PMID: 26052185 PMCID: PMC4449125 DOI: 10.1007/s10562-014-1420-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 11/04/2014] [Indexed: 11/21/2022]
Abstract
ABSTRACT Surface-enhanced Raman spectroscopy (SERS) and tip-enhanced Raman spectroscopy (TERS) were until recently limited in their applicability to the majority of heterogeneous catalytic reactions. Recent developments begin to resolve the conflicting experimental requirements for SERS and TERS on the one hand, and heterogeneous catalysis on the other hand. This article discusses the development and use of SERS and TERS to study heterogeneous catalytic reactions, and the exciting possibilities that may now be within reach thanks to the latest technical developments. This will be illustrated with showcase examples from photo- and electrocatalysis. GRAPHICAL ABSTRACT
Collapse
Affiliation(s)
- Clare E. Harvey
- Inorganic Chemistry and Catalysis group, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Bert M. Weckhuysen
- Inorganic Chemistry and Catalysis group, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| |
Collapse
|
8
|
Weng X, Ren H, Chen M, Wan H. Effect of Surface Oxygen on the Activation of Methane on Palladium and Platinum Surfaces. ACS Catal 2014. [DOI: 10.1021/cs500510x] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Xuefei Weng
- State Key
Laboratory of Physical
Chemistry of Solid Surfaces, National Engineering Laboratory for Green
Chemical Productions of Alcohols−Ethers−Esters, Department
of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China
| | - Hongjia Ren
- State Key
Laboratory of Physical
Chemistry of Solid Surfaces, National Engineering Laboratory for Green
Chemical Productions of Alcohols−Ethers−Esters, Department
of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China
| | - Mingshu Chen
- State Key
Laboratory of Physical
Chemistry of Solid Surfaces, National Engineering Laboratory for Green
Chemical Productions of Alcohols−Ethers−Esters, Department
of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China
| | - Huilin Wan
- State Key
Laboratory of Physical
Chemistry of Solid Surfaces, National Engineering Laboratory for Green
Chemical Productions of Alcohols−Ethers−Esters, Department
of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China
| |
Collapse
|
9
|
Bersani M, Conte L, Martucci A, Guglielmi M, Mattei G, Bello V, Rosei R, Centazzo M. Transmetallation as an effective strategy for the preparation of bimetallic CoPd and CuPd nanoparticles. NANOSCALE 2014; 6:1560-1566. [PMID: 24322302 DOI: 10.1039/c3nr04409b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The preparation of palladium alloy nanoparticles is of great interest for many applications, especially in catalysis. Starting from presynthesized nanoparticles of a less noble metal, a transmetallation reaction involving a redox process at the nanoparticle surface can be exploited to modify the nanoparticle composition and crystalline phase. As an example, monodispersed ε-cobalt and face-centered cubic copper nanoparticles were synthesized in organic solvents at high temperature and the as-formed nanoparticles were reacted with palladium(ii) hexafluoroacetylacetonate resulting in the formation of alloyed nanoparticles whose composition closely follows the reactant ratio. The oxidative state of the nanoparticle surface greatly affects the success of the transmetallation reaction and a reduction treatment was necessary to achieve the desired final product. Electron microscopy and X-ray diffraction showed that for cobalt a limiting palladium content for the ε-phase alloy is found, above which an fcc alloy nucleates, while for copper the fcc crystalline phase is preserved throughout the whole composition range.
Collapse
Affiliation(s)
- Marco Bersani
- University of Padova, Department of Industrial Engineering, via F. Marzolo 9, 35131 Padova, Italy.
| | | | | | | | | | | | | | | |
Collapse
|
10
|
|
11
|
Pomfret MB, Pietron JJ, Owrutsky JC. Measurement of benzenethiol adsorption to nanostructured Pt, Pd, and PtPd films using Raman spectroelectrochemistry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:6809-6817. [PMID: 20136124 DOI: 10.1021/la904107j] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Raman spectroscopy and electrochemical methods were used to study the behavior of the model adsorbate benzenethiol (BT) on nanostructured Pt, Pd, and PtPd electrodes as a function of applied potential. Benzenethiol adsorbs out of ethanolic solutions as the corresponding thiolate, and voltammetric stripping data reveal that BT is oxidatively removed from all of the nanostructured metals upon repeated oxidative and reductive cycling. Oxidative stripping potentials for BT increase in the order Pt < PtPd < Pd, indicating that BT adsorbs most strongly to nanoscale Pd. Yet, BT Raman scattering intensities, measured in situ over time scales of minutes to hours, are most persistent on the film of nanostructured Pt. Raman spectra indicate that adsorbed BT desorbs from nanoscale Pt at oxidizing potentials via cleavage of the Pt-S bond. In contrast, on nanoscale Pd and PtPd, BT is irreversibly lost due to cleavage of BT C-S bonds at oxidizing potentials, which leaves adsorbed sulfur oxides on Pd and PtPd films and effects the desulfurization of BT. While Pd and PtPd films are less sulfur-resistant than Pt films, palladium oxides, which form at higher potentials than Pt oxides, oxidatively desulfurize BT. In situ spectroelectrochemical Raman spectroscopy provides real-time, chemically specific information that complements the cyclic voltammetric data. The combination of these techniques affords a powerful and convenient method for guiding the development of sulfur-tolerant PEMFC catalysts.
Collapse
Affiliation(s)
- Michael B Pomfret
- Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA
| | | | | |
Collapse
|
12
|
Grdeń M. Electrochemical quartz crystal microbalance studies of a palladium electrode oxidation in a basic electrolyte solution. Electrochim Acta 2009. [DOI: 10.1016/j.electacta.2008.08.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
13
|
Yao JL, Yuan YX, Fan XM, Ren B, Gu RA, Tian ZQ. The reorientation of benzonitrile on Platinum electrode probed by surface enhanced Raman spectroscopy. J Electroanal Chem (Lausanne) 2008. [DOI: 10.1016/j.jelechem.2008.08.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
14
|
Grdeń M, Łukaszewski M, Jerkiewicz G, Czerwiński A. Electrochemical behaviour of palladium electrode: Oxidation, electrodissolution and ionic adsorption. Electrochim Acta 2008. [DOI: 10.1016/j.electacta.2008.05.046] [Citation(s) in RCA: 315] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
15
|
|
16
|
Cui L, Liu Z, Duan S, Wu DY, Ren B, Tian ZQ, Zou SZ. Orientation Change of Adsorbed Pyrazine on Roughened Rhodium Electrodes as Probed by Surface-Enhanced Raman Spectroscopy. J Phys Chem B 2005; 109:17597-602. [PMID: 16853251 DOI: 10.1021/jp052983y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A surface-enhanced Raman spectroscopic (SERS) study of pyrazine adsorbed on roughened Rh electrodes was performed. Potential and concentration effects on the adsorption behavior of pyrazine were investigated. The SER spectra display four pairs of overlapping bands with the relative intensity of each pair being highly potential dependent, which has not been observed on other metals. The orientation change of the adsorbed pyrazine from the end-on to N/pi bonded edge-on configuration is proposed to account for this potential-dependent relative intensity change. This hypothesis is further supported by the SERS results obtained at different pyrazine concentrations. In conjunction with the orientation effect, the interaction of Rh with hydrogen and oxygen generated at different potentials has a great influence on the adsorption configuration of pyrazine.
Collapse
Affiliation(s)
- Li Cui
- State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | | | | | | | | | | | | |
Collapse
|
17
|
Extent of PEMFC Cathode Surface Oxidation by Oxygen and Water Measured by CV. ACTA ACUST UNITED AC 2004. [DOI: 10.1149/1.1649698] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
18
|
Wieckowski A. Tribute to Professor Michael J. Weaver (1947–2002). J Electroanal Chem (Lausanne) 2003. [DOI: 10.1016/s0022-0728(03)00328-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
19
|
Demoulin O, Navez M, Gaigneaux EM, Ruiz P, Mamede AS, Granger P, Payen E. Operando resonance Raman spectroscopic characterisation of the oxidation state of palladium in Pd/γ-Al2O3catalysts during the combustion of methane. Phys Chem Chem Phys 2003. [DOI: 10.1039/b305817b] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
20
|
Wasileski SA, Weaver MJ. What can we learn about electrode-chemisorbate bonding energetics from vibrational spectroscopy? An assessment from density functional theory. Faraday Discuss 2002:285-300; discussion 331-64. [PMID: 12227575 DOI: 10.1039/b110950m] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An analysis is presented of the manner and extent to which the metal surface-chemisorbate bond energetics and geometries as functions of the metal and the applied field can be correlated with vibrational frequencies, with specific reference to electrochemical systems. Emphasis is placed on metal-adsorbate stretching frequencies, vM-A, using oxygen and carbon monoxide chemisorption as illustrative examples; the intramolecular stretch (vCO) of the latter adsorbate is also examined in view of the extensive experimental utilization of this vibrational mode. Results based on Density Functional Theory (DFT) are presented for finite-cluster models of Pt-group and coinage-metal (111) surfaces. The DFT calculations enable a separation between steric repulsion and orbital contributions to the potential-energy surface (PES), and additionally, in the case of CO chemisorption, between the 5sigma and 27pi* orbital components. While rough metal-dependent correlations between vM-A and the surface binding energy, -Eb, are observed, such a relationship is not expected in general. Thus for CO chemisorption, the variations in -Eb are affected more by changes in the 5sigma rather than 2pi* orbital energies, whereas these components influence the M-CO stretching frequency, vM-CO, to a comparable extent. Moreover, the metal-dependent vCO frequencies do not correlate even qualitatively with -Eb; this is because the former are dominated by 2pi*, rather than 5sigma, interactions. The factors influencing the field (F) (and hence electrode potential) dependence of Eb versus VM-CO and vCO mirror somewhat this pattern. While the field-dependent influence of the 5sigma and 2pi* interactions are offsetting, the latter affects the vM CO-F, and especially the vCO-F, behavior to a greater extent than the -Eb-F dependence. Generally, then, the lack of broad-based correlations between chemisorbate vibrational frequencies and binding energetics can be understood in terms of the differing influence of the individual interaction components on the PES well shape and depth. The description of such bonding contributions in terms of dipole-moment parameters is illustrated. Also considered are relations between vibrational frequencies and bond lengths.
Collapse
Affiliation(s)
- Sally A Wasileski
- Department of Chemistry, Purdue University West Lafayette, Indiana 47907, USA.
| | | |
Collapse
|
21
|
Mrozek MF, Wasileski SA, Weaver MJ. Periodic trends in electrode-chemisorbate bonding: benzonitrile on platinum-group and other noble metals as probed by surface-enhanced Raman spectroscopy combined with density functional theory. J Am Chem Soc 2001; 123:12817-25. [PMID: 11749539 DOI: 10.1021/ja010049k] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Detailed intramolecular vibrational spectra obtained by means of surface-enhanced Raman scattering (SERS) for benzonitrile adsorbed on seven electrode surfaces-four Pt-group metals (platinum, palladium, rhodium, and iridium) and the Group IB metals (copper, silver, and gold)-are reported with the aim of exploring the metal-dependent nature of surface-chemisorbate interactions. The Pt-group surfaces were prepared as ultrathin electrodeposited films on gold, enabling the SERS activity inherent to the substrate to be imparted to the overlayer material. Benzonitrile was selected as a "model" organic adsorbate since it displays a rich array of coupled aromatic ring as well as substituent modes which collectively can provide insight into the various molecular perturbations induced by surface coordination via the nitrile substituent. The experimental spectra are compared with ab initio calculations of vibrational frequencies, bond geometries, and charge distributions obtained by means of Density Functional Theory (DFT), which yields valuable insight into the underlying structural reasons for the sensitivity of the experimental coordination-induced frequency shifts to the nature of the intramolecular mode and the metal surface. The DFT results also form an invaluable aid in making SER spectral assignments, along with providing detailed information on the coupled atomic displacements involved in each vibrational mode. Benzonitrile surface coordination was modeled in the DFT calculations by binding the nitrile group to metal atoms and small metal clusters. While the majority of the aromatic-ring SER frequencies are altered only slightly (approximately < 5 cm(-1)) upon surface coordination, several modes (especially nu(1), nu(6a)) are blue-shifted substantially (by up to 50 cm(-1)). These shifts were identified by DFT as arising from mode coupling to the nitrile substituent, especially involving the C-CN bond that is compressed upon nitrile coordination, associated with metal-adsorbate back-donation. The small (<5 cm(-1)) red-shifts seen for ring vibrations not involving coupled substituent motion apparently arise from increased antibonding aromatic electron density. The metal-dependent frequency shifts seen for these coupled aromatic vibrations as well as for the more localized C-N nitrile stretching mode are consistent with increased back-donation anticipated in the sequence d(10) < d(9) < d(8) within a given Periodic row. Overall, the findings provide a benchmark illustration of the virtues of DFT in interpreting complex vibrational spectra for larger polyatomic adsorbates.
Collapse
Affiliation(s)
- M F Mrozek
- Department of Chemistry, Purdue University, West Lafayette, IN 47907-1393, USA
| | | | | |
Collapse
|
22
|
Mrozek MF, Xie Y, Weaver MJ. Surface-enhanced Raman scattering on uniform platinum-group overlayers: preparation by redox replacement of underpotential-deposited metals on gold. Anal Chem 2001; 73:5953-60. [PMID: 11791565 DOI: 10.1021/ac0106391] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The preparation of Pt-group metal films on roughened gold electrodes by utilizing spontaneous redox replacement of an underpotential-deposited (upd) copper or lead monolayer with a Pt-group metal cation solute is described. The resulting films display intense surface-enhanced Raman scattering (SERS) for adsorbates bound to the overlayer and free from substrate interferences. This strategy provides a useful alternative, at least for platinum, to the constant-current electrodeposition method commonly utilized to prepare SERS-active Pt-group metal films (Zou, S.; Weaver, M. J. Anal. Chem. 1988, 70. 2387). Similarly to related earlier studies, the film uniformity (specifically, the absence or otherwise of residual Au "pinhole" sites) was tested by employing carbon monoxide, and also ethylene, as "probe" chemisorbates, since they yield vibrational frequencies on Au that are blue-shifted from the corresponding bands for adsorbate bound to Pt-group metal sites. While a single redox replacement of upd Cu with Pt(IV) yielded incomplete surface coverage, as expected, the use of multiple (up to eight) replacement cycles produced Pt films displaying remarkably intense CO vibrational bands as well as apparently "pinhole-free" properties, although such imperfections were detected with the ethylene probe. A single upd Cu replacement with Pt(II), however, yielded a remarkably uniform Pt layer, as indicated by pinhole-free characteristics using both the CO and ethylene probes along with the voltammetric behavior. The use of additional redox replacement cycles yielded marked progressive attenuation in the SERS signals. Comparable, although less optimal, SERS behavior was obtained for Pd films prepared similarly from Pd(II). The value of the strategy for exploring catalytic as well as equilibrium adsorptive chemistry on Pt surfaces is also illustrated.
Collapse
Affiliation(s)
- M F Mrozek
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-1393, USA
| | | | | |
Collapse
|
23
|
Hahn F, Melendres C. Anodic oxidation of methane at noble metal electrodes: an ‘in situ’ surface enhanced infrared spectroelectrochemical study. Electrochim Acta 2001. [DOI: 10.1016/s0013-4686(01)00649-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
24
|
de Vooys A, Mrozek M, Koper M, van Santen R, van Veen J, Weaver M. The nature of chemisorbates formed from ammonia on gold and palladium electrodes as discerned from surface-enhanced Raman spectroscopy. Electrochem commun 2001. [DOI: 10.1016/s1388-2481(01)00156-4] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
|
25
|
A versatile surface Raman spectroelectrochemical flow cell: applications to chemisorbate kinetics. J Electroanal Chem (Lausanne) 2001. [DOI: 10.1016/s0022-0728(00)00517-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
26
|
Ren B, Li X, She C, Wu D, Tian Z. Surface Raman spectroscopy as a versatile technique to study methanol oxidation on rough Pt electrodes. Electrochim Acta 2000. [DOI: 10.1016/s0013-4686(00)00573-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
27
|
Luo H, Park S, Chan HYH, Weaver MJ. Surface Oxidation of Platinum-Group Transition Metals in Ambient Gaseous Environments: Role of Electrochemical versus Chemical Pathways. J Phys Chem B 2000. [DOI: 10.1021/jp001289+] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|