Electrochemical Optical Spectroscopy of Metals

Brodskii, A.M.; Daikhin, Leonid; Urbakh, Michael

doi:10.1070/rc1985v054n01abeh002959

“…But their already high density of charge carriers in the bulk is difficult to alter significantly by applying an external voltage. However, it is possible to strongly alter the surface charge carrier density of gold films by immersing them in an electrolyte and applying a voltage 3 4 5 6 7 8 . The accessible surface area is limited in this case.…”

mentioning

confidence: 99%

“…Gold and other metals have already been used for optical electrochemical experiments in various shapes and forms. Among these are continuous metal films 3 4 5 6 7 8 , metallic nanoparticles 25 26 27 28 , nanoholes in metal films 29 30 , as well as metamaterials 20 31 32 . This large interest originates from the fact that metals are able to strongly concentrate light and by that allow for very localized and sensitive measurements.…”

mentioning

confidence: 99%

Electrochemical tuning of the optical properties of nanoporous gold

Jalas

¹

,

Shao

²

,

Canchi

³

et al. 2017

Sci Rep

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Using optical in-situ measurements in an electrochemical environment, we study the electrochemical tuning of the transmission spectrum of films from the nanoporous gold (NPG) based optical metamaterial, including the effect of the ligament size. The long wavelength part of the transmission spectrum around 800 nm can be reversibly tuned via the applied electrode potential. The NPG behaves as diluted metal with its transition from dielectric to metallic response shifted to longer wavelengths. We find that the applied potential alters the charge carrier density to a comparable extent as in experiments on gold nanoparticles. However, compared to nanoparticles, a NPG optical metamaterial, due to its connected structure, shows a much stronger and more broadband change in optical transmission for the same change in charge carrier density. We were able to tune the transmission through an only 200 nm thin sample by 30%. In combination with an electrolyte the tunable NPG based optical metamaterial, which employs a very large surface-to-volume ratio is expected to play an important role in sensor applications, for photoelectrochemical water splitting into hydrogen and oxygen and for solar water purification.

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“…For comparison, ab initio calculations for Cu(110) in equilibrium with ambient water vapor pressures disclosed several stable surface adsorbate structures that all comprise water layer density according to the number of copper atoms at the (110) surface. 65 The electron excess at potential (1) under consideration of a water layer with 2 times higher density increases in comparison to the calculations without the water overlayer from Γ e = 2.83 × 10 15 cm 2 (453 μC/cm 2 ) to Γ e (1) = 3.4 × 10 15 cm −2 (Q e (1) = 540 μC/ cm 2 ).…”

Section: Discussionmentioning

confidence: 82%

“…For the upper half space, we use the refractive index of water from ref . The measured Ψ and Δ are related to r p and r s , by The line shapes of the real and imaginary part of the DF calculated in such a way, e.g., for the Cu(111), are similar to those plotted in Figure . It shows the known features of the Drude-like free electron resonance and above ∼2 eV structures of d-band excitations .…”

Section: Discussionmentioning

confidence: 98%

“…In the case of sub-monolayer coverages, however, a quantification of material parameters on the basis of the optical response is difficult. A decent optical model has to include a correct description of (i) the electrolyte near the surface, (ii) surface adsorbates, (iii) electromodulation effects − in the electrode surface, and (iv) if necessary the morphology of the surface. , A promising model for the adsorption of anions on different amorphous metal electrodes was described by Chiu and Genshaw as well as by Paik and Bockris et al…”

Section: Introductionmentioning

confidence: 99%

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In Situ Optical Quantification of Adsorbates and Surface Charges on Copper Crystals and Their Impact on the Hydrogen Evolution Reaction in Hydrochloric Electrolytes

Chien

¹

,

Vazquez-Miranda

²

,

Sharif

³

et al. 2018

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In situ spectroscopic ellipsometry is combined with cyclic voltammetry to discover and quantify potential-dependent surface adsorbates and the electronic charge on copper single crystals in HCl solution. In comparison with electrochemical scanning tunneling microscopy, it is demonstrated that ellipsometry provides not only an extremely high finger print sensitivity to sub-monolayer surface modifications but that it is furthermore possible to determine qualified values with an appropriate optical model. As a critical bench mark we use the amount of adsorbed Cl– at the Cu(111) surface. In this context, we found clear optical evidence for a densified water layer at the Cu(111) surface. Particular attention is drawn to the potential range of the hydrogen evolution reaction and the catalytic efficiency of the relatively stable Cu(111) and the more open corrugated (110) surface. With the introduced ellipsometric method, we disclose a steplike increase of the surface electron excess and a decreasing lateral surface electron mobility at the onset of the hydrogen evolution reaction. Both are explained by protonation of the surface or the adsorbed water layer and demonstrate an unexpected inhibiting effect to the hydrogen evolution reaction.

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Electrochemical Interfaces: At the Border Line

Kornyshev

¹

,

Spohr

²

,

Воротынцев

³

2002

Encyclopedia of Electrochemistry

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The sections in this article are Introduction Basic Concepts Thermodynamics of Electrified Interfaces Classical Models of Electrified Interfaces Helmholtz Model Gouy–Chapman–Stern–Grahame Model Diffuse and Compact Layer Properties Grahame Model in Comparison with Capacitance Data for Liquid Electrodes Compact Layer Properties Manifestations of the Diffuse Layer in Kinetics of Electrode Reactions Electrokinetic Phenomena Solid Electrodes: Effects of Polycrystallinity and Surface Roughness “Uniform” Model of Solid Electrodes. Surface Roughness Crystallographic Inhomogeneity Effects for Solid Electrode Surfaces EDL Structure for NonUniform Electrode Surfaces Surface Roughness Effect on the Diffuse‐Layer Capacitance Semi‐phenomenological Nonlocal Theory of the Double Layer Basic Equations “Dipolar” Models of the Compact Layer Two‐State Model Multistate Models The Role of Metal Electrons Surface Electronic Profile and its Response to Charging Response to Charging of the Electrochemical Interface and the Compact‐Layer Capacitance: Main Qualitative Effects Optical Response and the Interfacial Structure Effects of the Molecular Nature of Electrolyte Solutions Ionic Adsorption Qualitative Aspects Ion Adsorption Models Image Potential for Ions in the Diffuse or Compact Layer Interaction Between Adsorbed Ions Statistical Mechanics of Adsorbed Ion Ensemble Ion Adsorption Isotherm Electric Field‐Induced Modifications of the Surface Structure Electrochemical Missing Row Reconstruction: Facts and Speculations Driving Force for Reconstruction Ising Model. Order–Disorder Transitions Roughening Transitions Soft Electrochemical Interfaces Capillary Waves at ITIES . Field Effect on Capillary Waves and Capillary Waves Effect on Capacitance Ion Penetration into an “Unfriendly Medium” From Basic Concepts to Surface Electrochemistry

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Electrochemical Optical Spectroscopy of Metals

Cited by 8 publications

References 8 publications

Electrochemical tuning of the optical properties of nanoporous gold

Electrochemical tuning of the optical properties of nanoporous gold

In Situ Optical Quantification of Adsorbates and Surface Charges on Copper Crystals and Their Impact on the Hydrogen Evolution Reaction in Hydrochloric Electrolytes

Electrochemical Interfaces: At the Border Line

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