Electrochemical Behavior and Specific Adsorption of an Iodide-based Ionic Liquid on Au(111)

Ueda, Hiroyuki; Nishiyama, Katsuhiko

doi:10.5796/electrochemistry.18-00028

Cited by 8 publications

(6 citation statements)

References 22 publications

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“…Figure S2 shows the results of the XPS measurements performed on the samples after the above-mentioned optical measurements to investigate the electronic structure and the amount of MgPc molecules. The Au 4f and I 3d spectra shown in Figures S2a and S2b, respectively, suggest that iodine adsorption causes a slight positive charge on the Au(111) substrate, as reported in previous studies. , The C 1s peaks in Figure S2c are broad for both samples, suggesting the existence of various adsorption structures, in addition to the different chemical states expected from the molecular structures. The presence of the O 1s peak in Figure S2e can be attributed to a water molecule strongly coordinating with the MgPc molecules. ,− In contrast to the cases of C 1s and O 1s, the peak position of N 1s in Figure b differs significantly depending on the presence of the iodine monolayer, indicating that the electronic state of the MgPc molecule has changed.…”

Section: Results and Discussionsupporting

confidence: 84%

Monatomic Iodine Dielectric Layer for Multimodal Optical Spectroscopy of Dye Molecules on Metal Surfaces

et al. 2021

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Fluorescence and Raman scattering spectroscopies have been used in various research fields such as chemistry, electrochemistry, and biochemistry because they can easily obtain detailed information about molecules at interfaces with visible light. In particular, multimodal fluorescence and Raman scattering spectroscopy have recently attracted significant attention, which enables us to distinguish chemical species and their electronic states that are important for expressing various functions. However, a special strategy is required to perform simultaneous measurements because the cross sections of fluorescence and Raman scattering differ by as much as ∼10 14 . In this study, we propose a method for the simultaneous measurement of dye molecules on a metal surface using a monatomic layer of iodine as the dielectric layer. The method is based on adequately quenching the photoexcited state of the molecules near the metal surface to weaken the fluorescence intensity and using the resonance effect to increase the Raman signal. We have validated this concept by experiments with insulating layers of different thicknesses and dye molecules of different chemical structures. The proposed multimodal strategy paves the way for various applications such as catalytic chemistry and electrochemistry, where the adsorption structure and electronic states of molecular species near the metal surface determine functionalities.

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Section: Results and Discussionsupporting

confidence: 84%

Monatomic Iodine Dielectric Layer for Multimodal Optical Spectroscopy of Dye Molecules on Metal Surfaces

et al. 2021

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“…[55][56][57] Gibbs energy of iodide adsorption at Cd (0001) and Bi(hkl) single-crystal electrodes was determined (increase in the sequence H 2 O < MeOH < EtOH < EC < PC < gamma-butyrolactone < AN), but there was no clear separation of the adsorption process from faradaic iodide oxidation.. [58] Anion adsorption has been investigated on Bi(hkl), and Cd (0001) surfaces in ionic liquid by electrochemical impedance method as well as differential capacitance measurements. [58] The specific adsorption of iodide on an Au(111) electrode surface in the ionic liquid was examined via voltammetric analyses, XPS, and STM; [59] ffi ffi ffi 3 p � ffi ffi ffi 3 p À � and p � ffi ffi ffi 3 p À � was found similar to the aqueous system. [30] This work is a continuation of our previous publication, in which we studied the influence of iodide concentration and various cations on the adsorption rate and extent of adsorption in propylene carbonate.…”

Section: Introductionmentioning

confidence: 99%

“…Anion adsorption has been investigated on Bi(hkl), and Cd(0001) surfaces in ionic liquid by electrochemical impedance method as well as differential capacitance measurements [58] . The specific adsorption of iodide on an Au(111) electrode surface in the ionic liquid was examined via voltammetric analyses, XPS, and STM; [59]

(\sqrt{3} \times \sqrt{3}) a n d (p \times \sqrt{3})

was found similar to the aqueous system [30] …”

Section: Introductionmentioning

confidence: 99%

Adsorption of Iodide and Bromide on Au(111) Electrodes from Aprotic Electrolytes: Role of the Solvent

2020

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The adsorption of iodide and bromide ions on Au(111) singlecrystal electrodes in three organic solvents [propylene carbonate (PC), diglyme (DG), and dimethyl sulfoxide (DMSO)] was studied by differential capacity measurements, cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The anion adsorption charge in DMSO is approximately half as large as in propylene carbonate and that in water. Quantification of the adsorbed iodide amount from XPS spectra confirms the coverage estimated from the adsorption charge in CVs. As expected, the rate of anion adsorption on Au(111) is higher for I À than for Br À due to better solvation of the latter. The extent of anion adsorption on Au(111) electrode decreases and the corresponding adsorption rate decreases in the solvent order H 2 O > PC > DG > DMSO. Since the donor number (DN) of the solvent increases in the same order (PC < DG < DMSO), we assume that it plays a decisive role since it determines the chemical interaction of the solvent with the metal surface. Moreover, the adsorption rate of iodide and the extent of its adsorption is increased with increasing water content in PC and DMSO. This effect, and the much higher adsorption rate in water is explained by the closer approach of the solvated halogen ion to the surface and the resulting stronger interaction of the transition state with the electrode.

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“…As indicated using the solid lines, no significant differences in the voltammetric shape at the anodic scan were identified between Au( hkl ). During the cathodic scan, a voltammetric peak generated by the from the reductive desorption of the iodine adlayer on Au( hkl ) appeared at approximately –2.20 V vs. Fc/Fc + [1] , [9] . Furthermore, the | j | value during the E pw-CL determining reduction was lowest for Au(110).…”

Section: Data Descriptionmentioning

confidence: 99%

Dataset of the electrochemical potential windows for the Au(hkl)|ionic liquid interfaces defined by the cut-off current densities

Ueda

2021

Data in Brief

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This data article describes the linear sweep voltammetry (LSV) profiles of five ionic liquids (ILs) at the low-index ( hkl ) ( hkl = 111, 100, and 110) planes of Au. The LSV profiles were recorded at 25 ± 1°C for the Au( hkl )|IL interfaces maintained in a hanging meniscus configuration in an inert Ar atmosphere (with H 2 O and O 2 concentrations being lower than 5 ppm). The width of the electrical double-layer regions ( E dl ) and the electrochemical potential windows ( E pw ) of the ILs were evaluated based on the cut-off current densities ( j cut-off ): ±5, ±10, and ±20 µA cm –2 for E dl and ±0.1, ±0.5, and ±1.0 mA cm –2 for E pw . The potential values were calibrated to the redox potential of ferrocene/ferrocenium in each IL. A detailed discussion on the electrochemical behaviors of the ILs on Au( hkl ) is provided in the related article “Voltammetric Investigation of Anodic and Cathodic Processes at Au( hkl )|Ionic Liquid Interfaces”, published in the Journal of Electroanalytical Chemistry (Ueda and Yoshimoto, 2021).

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Electrochemical Behavior and Specific Adsorption of an Iodide-based Ionic Liquid on Au(111)

Cited by 8 publications

References 22 publications

Monatomic Iodine Dielectric Layer for Multimodal Optical Spectroscopy of Dye Molecules on Metal Surfaces

Monatomic Iodine Dielectric Layer for Multimodal Optical Spectroscopy of Dye Molecules on Metal Surfaces

Adsorption of Iodide and Bromide on Au(111) Electrodes from Aprotic Electrolytes: Role of the Solvent

Dataset of the electrochemical potential windows for the Au(hkl)|ionic liquid interfaces defined by the cut-off current densities

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