The influence of halide adsorption on the electronic surface states of silver electrodes

Franke, Christine; Piazza, G.; Kolb, Dieter M.

doi:10.1016/0013-4686(89)80011-8

Cited by 21 publications

(16 citation statements)

References 13 publications

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“…At higher potentials, the formation of a CuI compound film was reported . The uniaxially incommensurate iodide adlayer structure on Cu(100) shows an additional one-dimensional long-range height modulation that differs from that found on Au(100), Ni(100), Ag(100), and Pt(100) . Hence, the system I/Cu(100) appears to be an interesting template for the adsorption of Pc molecules.…”

Section: Resultsmentioning

confidence: 97%

Unusual Demetalation and Ordered Adsorption of a Pyridine-Appended Zinc Phthalocyanine at Metal–Electrolyte Interfaces Studied by in Situ Scanning Tunneling Microscopy and X-ray Photoelectron Spectroscopy

et al. 2013

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A combination of cyclic voltammetry, in situ electrochemical scanning tunneling microscopy (EC-STM), and ex situ X-ray photoelectron spectroscopy (XPS) studies was employed to investigate the electrochemical behavior and to characterize the structure of adsorbed layers of a redox-active pyridine-appended zinc phthalocyanine (ZnPc) at Cu(100)/electrolyte interfaces. Additional cyclic voltammograms (CVs) of a HOPG electrode in phthalocyanine- and iodide-containing electrolyte showed four redox peak pairs related to the phthalocyanine macrocycle. Focusing on the reduction processes, the four observed cathodic waves were assigned to four single electron transfer steps causing four successive reductions of the phthalocyanine. Due to its narrow potential window, the CV of Cu(100) in the same electrolyte covers only the first three reduction features in the acidic solution superimposed by the CuI formation/dissolution processes. Surprisingly, the XPS data from the iodide and phthalocyanine covered Cu(100) surface, however, revealed a demetalation of the molecules, that is, a replacement of the central zinc atom of adsorbed ZnPc + by hydrogen atoms resulting in the formation of the corresponding free base phthalocyanine H2Pc+. These H2Pc+ molecules form highly ordered adlayers on the iodide-modified Cu(100) surface with the coexistence of different phases, that is, one with a square-shaped unit cell enclosing an angle of (91 ± 2)° and a rhombic one with an angle of (66 ± 2)°, and intermolecular distances of 2.0 ± 0.1 nm and 2.3 ± 0.1 nm, respectively. The main symmetry axes of the H2Pc+ adlayer run parallel neither to the commensurate direction of the iodide layer underneath nor to the close-packed atomic rows of the copper substrate. Detailed molecular models are proposed which are in agreement with the patterns experimentally observed with EC-STM.

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Section: Resultsmentioning

confidence: 97%

Unusual Demetalation and Ordered Adsorption of a Pyridine-Appended Zinc Phthalocyanine at Metal–Electrolyte Interfaces Studied by in Situ Scanning Tunneling Microscopy and X-ray Photoelectron Spectroscopy

et al. 2013

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“…compared tetrafluoroborate (BF 4 − ) and Br − anions in tetrabutylammonium solutions. Figure 2 illustrates how specific adsorption [34,42,43] at the Ag surface of Cl − , Br − , and I − in choline‐based electrolytes may provide a basis to discuss the observed FE CO trends in ChCl, ChBr, and ChI at potentials in the range −0.7 to −1.0 V vs. RHE (Figure 1). As smaller anions are more strongly hydrated than larger anions [34] the interactions between the Ag electrode and halide anions increase in the order Cl − <Br − <I − , meaning the surface coverage of halide anions also increases in the same order Cl − <Br − <I − , as illustrated in Figure 2 [44] .…”

Section: Resultsmentioning

confidence: 99%

Understanding the Effects of Anion Interactions with Ag Electrodes on Electrochemical CO₂ Reduction in Choline Halide Electrolytes

Garg

et al. 2021

ChemSusChem

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Interactions of electrolyte ions at electrocatalyst surfaces influence the selectivity of electrochemical CO2 reduction (CO2R) to chemical feedstocks like CO. We investigated the effects of anion type in aqueous choline halide solutions (ChCl, ChBr, and ChI) on the selectivity of CO2R to CO over an Ag foil cathode. Using an H‐type cell, we observed that halide‐specific adsorption at the Ag surface limits CO faradaic efficiency (FECO) at potentials more positive than −1.0 V vs. reversible hydrogen electrode (RHE). At these conditions, FECO increased from I−90 %) in ChCl (at −0.75±0.06 Vvs. RHE) and ChI (at −0.78±0.17 V vs. RHE) could be achieved at a current density of 150 mA cm−2 in a continuous flow‐cell electrolyser with Ag nanoparticles on a commercial gas diffusion electrode. This study provides new insights to understand the interactions of anions with catalysts and offers a new method to modify electrocatalyst surfaces.

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“…A variety of spectroscopic investigations of the interactions of adsorbates with metal surfaces have been reported, based on infrared, Raman, UV-vis reflectance, and fluorescence spectroscopies as well as UHV surface science and electrochemical probes. 7, [25][26][27][28][29][30][31][32] Electron transfer from a metal to a tethered redox center has been examined in many laboratories, often involving self-assembled monolayers on gold surfaces. [33][34][35][36][37][38][39] For aliphatic tethers, electronic coupling is weak, and tunneling through the aliphatic chain controls electron transfer.…”

Section: Introductionmentioning

confidence: 99%

In Situ Raman Spectroelectrochemistry of Electron Transfer between Glassy Carbon and a Chemisorbed Nitroazobenzene Monolayer

2002

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In situ Raman spectroscopy was used to monitor 4-nitroazobenzene (NAB) in an electrochemical cell, both as a free molecule and as a chemisorbed monolayer on a glassy carbon (GC) electrode surface. Reduction of free NAB exhibited two well-defined voltammetric couples in acetonitrile, and the accompanying spectral changes supported a mechanism involving two successive 1-e(-) transfers. Raman spectra of NAB chemisorbed to GC via diazonium ion reduction were obtained in acetonitrile with a high-sensitivity, line-focused CCD spectrometer. The chemisorbed NAB spectra were quite different from the free NAB spectra, and were sufficiently strong to monitor as a function of applied potential. In the potential range of +400 to -800 mV vs Ag/Ag(+), the intensity of the Raman bands associated with the phenyl-NO(2) moiety varied, implying an electronic interaction between the pi system of the graphitic substrate and the chemisorbed NAB molecules. Negative of -800 mV, a 1-e(-) voltammetric reduction peak was observed, which was reversible on the positive voltage scan. This peak was accompanied by significant spectral changes, particularly the loss of the N=N and NO(2) stretches. The spectra are consistent with formation of a quinoid structure containing a C=C double bond between the NAB and the graphitic surface. The electron transfer and spectral changes occurred over a wider potential range than expected for a conventional Nernstian equilibrium, but did not appear to be broadened by slow electron-transfer kinetics. The results imply a significant perturbation of electron transfer between the GC and the monolayer, caused by strong electronic coupling between the graphitic pi system and the NAB orbitals. Rather than a discrete electron transfer to a free molecule, the electron transfer to chemisorbed NAB is more gradual, and is presumably driven by the electric field at the electrode/solution interface.

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The influence of halide adsorption on the electronic surface states of silver electrodes

Cited by 21 publications

References 13 publications

Unusual Demetalation and Ordered Adsorption of a Pyridine-Appended Zinc Phthalocyanine at Metal–Electrolyte Interfaces Studied by in Situ Scanning Tunneling Microscopy and X-ray Photoelectron Spectroscopy

Unusual Demetalation and Ordered Adsorption of a Pyridine-Appended Zinc Phthalocyanine at Metal–Electrolyte Interfaces Studied by in Situ Scanning Tunneling Microscopy and X-ray Photoelectron Spectroscopy

Understanding the Effects of Anion Interactions with Ag Electrodes on Electrochemical CO₂ Reduction in Choline Halide Electrolytes

In Situ Raman Spectroelectrochemistry of Electron Transfer between Glassy Carbon and a Chemisorbed Nitroazobenzene Monolayer

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The influence of halide adsorption on the electronic surface states of silver electrodes

Cited by 21 publications

References 13 publications

Unusual Demetalation and Ordered Adsorption of a Pyridine-Appended Zinc Phthalocyanine at Metal–Electrolyte Interfaces Studied by in Situ Scanning Tunneling Microscopy and X-ray Photoelectron Spectroscopy

Unusual Demetalation and Ordered Adsorption of a Pyridine-Appended Zinc Phthalocyanine at Metal–Electrolyte Interfaces Studied by in Situ Scanning Tunneling Microscopy and X-ray Photoelectron Spectroscopy

Understanding the Effects of Anion Interactions with Ag Electrodes on Electrochemical CO2 Reduction in Choline Halide Electrolytes

In Situ Raman Spectroelectrochemistry of Electron Transfer between Glassy Carbon and a Chemisorbed Nitroazobenzene Monolayer

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Understanding the Effects of Anion Interactions with Ag Electrodes on Electrochemical CO₂ Reduction in Choline Halide Electrolytes