Interfacial structure and electrochemical stability of electrolytes: methylene methanedisulfonate as an additive

2019 ◽  
Vol 21 (1) ◽  
pp. 217-223 ◽  
Author(s):  
Yamin Wang ◽  
Xiaoying Yu ◽  
Yingchun Liu ◽  
Qi Wang
Keyword(s):  
Electrochemical Stability ◽  
Interfacial Structure ◽  
Electrode Surfaces ◽  
Electrode Interface

MMDS has a higher affinity for electrode surfaces than solvents and could reduce the probability of finding solvent–ion complexes at the electrolyte–electrode interface.

scholarly journals In Situ Determination of pH at Nanostructured Carbon Electrodes Using IR Spectroscopy

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4044
Author(s):  
Lolade Bamgbelu ◽  
Katherine B Holt
Keyword(s):  
Ir Spectroscopy ◽  
Redox Reactions ◽  
Ph Change ◽  
Ph Changes ◽  
Electrode Surfaces ◽  
Phosphate Ions ◽  
Phosphate Species ◽  
Analytical Importance ◽  
Electrode Interface

Changes in pH at electrode surfaces can occur when redox reactions involving the production or consumption of protons take place. Many redox reactions of biological or analytical importance are proton-coupled, resulting in localized interfacial pH changes as the reaction proceeds. Other important electrochemical reactions, such as hydrogen and oxygen evolution reactions, can likewise result in pH changes near the electrode. However, it is very difficult to measure pH changes located within around 100 µm of the electrode surface. This paper describes the use of in situ attenuated total reflectance (ATR) infrared (IR) spectroscopy to determine the pH of different solutions directly at the electrode interface, while a potential is applied. Changes in the distinctive IR bands of solution phosphate species are used as an indicator of pH change, given that the protonation state of the phosphate ions is pH-dependent. We found that the pH at the surface of an electrode modified with carbon nanotubes can increase from 4.5 to 11 during the hydrogen evolution reaction, even in buffered solutions. The local pH change accompanying the hydroquinone–quinone redox reaction is also determined.

Modeling Insight into Battery Electrolyte Electrochemical Stability and Interfacial Structure

2017 ◽  
Vol 50 (12) ◽  
pp. 2886-2894 ◽  
Author(s):  
Oleg Borodin ◽  
Xiaoming Ren ◽  
Jenel Vatamanu ◽  
Arthur von Wald Cresce ◽  
Jaroslaw Knap ◽  
...  
Keyword(s):  
Electrochemical Stability ◽  
Interfacial Structure ◽  
Battery Electrolyte ◽  
Insight Into

In situ observation of the potential-dependent structure of an electrolyte/electrode interface by heterodyne-detected vibrational sum frequency generation

2020 ◽  
Vol 22 (4) ◽  
pp. 2580-2589 ◽  
Author(s):  
Atsushi Sayama ◽  
Satoshi Nihonyanagi ◽  
Yasuhiro Ohshima ◽  
Tahei Tahara
Keyword(s):  
Molecular Level ◽  
Sum Frequency Generation ◽  
Interfacial Structure ◽  
In Situ Observation ◽  
Sum Frequency ◽  
Electrochemical Interface ◽  
Electrode Interface ◽  
Frequency Generation

HD-VSFG spectroscopy reveals the potential-dependent interfacial structure of an electrochemical interface at the molecular level.

scholarly journals Doped Polythiophene Chiral Electrodes as Electrochemical Biosensors

Electrochem ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 677-688
Author(s):  
M’hamed Chahma
Keyword(s):  
Electronic Properties ◽  
Alternative Pathway ◽  
Electrochemical Stability ◽  
Electrochemical Biosensors ◽  
Surface Immobilization ◽  
Electrode Surfaces ◽  
Conducting Materials ◽  
Wide Range

π-conducting materials such as chiral polythiophenes exhibit excellent electrochemical stability in doped and undoped states on electrode surfaces (chiral electrodes), which help tune their physical and electronic properties for a wide range of uses. To overcome the limitations of traditional surface immobilization methods, an alternative pathway for the detection of organic and bioorganic targets using chiral electrodes has been developed. Moreover, chiral electrodes have the ability to carry functionalities, which helps the immobilization and recognition of bioorganic molecules. In this review, we describe the use of polythiophenes for the design of chiral electrodes and their applications as electrochemical biosensors.

Off-axis electron holography applied to the study of interfaces

1992 ◽  
Vol 50 (1) ◽  
pp. 244-245
Author(s):  
J.K. Weiss ◽  
M. Gajdardziska-Josifovska ◽  
M. R. McCartney ◽  
David J. Smith
Keyword(s):  
Electric Fields ◽  
Resolution Enhancement ◽  
Interfacial Structure ◽  
Atomic Scale ◽  
Bulk Property ◽  
Electron Holography ◽  
Specimen Thickness ◽  
Composition And Structure ◽  
Chemical Segregation ◽  
Diffraction Effects

Interfacial structure is a controlling parameter in the behavior of many materials. Electron microscopy methods are widely used for characterizing such features as interface abruptness and chemical segregation at interfaces. The problem for high resolution microscopy is to establish optimum imaging conditions for extracting this information. We have found that off-axis electron holography can provide useful information for the study of interfaces that is not easily obtained by other techniques.Electron holography permits the recovery of both the amplitude and the phase of the image wave. Recent studies have applied the information obtained from electron holograms to characterizing magnetic and electric fields in materials and also to atomic-scale resolution enhancement. The phase of an electron wave passing through a specimen is shifted by an amount which is proportional to the product of the specimen thickness and the projected electrostatic potential (ignoring magnetic fields and diffraction effects). If atomic-scale variations are ignored, the potential in the specimen is described by the mean inner potential, a bulk property sensitive to both composition and structure. For the study of interfaces, the specimen thickness is assumed to be approximately constant across the interface, so that the phase of the image wave will give a picture of mean inner potential across the interface.

A TEM study of the interface between organic matrix and aragonite in a biological hard tissue, nacre

1992 ◽  
Vol 50 (2) ◽  
pp. 1024-1025
Author(s):  
Jun Liu ◽  
Katie E. Gunnison ◽  
Mehmet Sarikaya ◽  
Ilhan A. Aksay
Keyword(s):  
Mechanical Properties ◽  
Ion Beam ◽  
Laminated Composite ◽  
Organic Matrix ◽  
Pearl Oyster ◽  
Interfacial Structure ◽  
Interfacial Region ◽  
Thin Sections ◽  
Organic Layers ◽  
Transmission Electron

The interfacial structure between the organic and inorganic phases in biological hard tissues plays an important role in controlling the growth and the mechanical properties of these materials. The objective of this work was to investigate these interfaces in nacre by transmission electron microscopy. The nacreous section of several different seashells -- abalone, pearl oyster, and nautilus -- were studied. Nacre is a laminated composite material consisting of CaCO3 platelets (constituting > 90 vol.% of the overall composite) separated by a thin organic matrix. Nacre is of interest to biomimetics because of its highly ordered structure and a good combination of mechanical properties. In this study, electron transparent thin sections were prepared by a low-temperature ion-beam milling procedure and by ultramicrotomy. To reveal structures in the organic layers as well as in the interfacial region, samples were further subjected to chemical fixation and labeling, or chemical etching. All experiments were performed with a Philips 430T TEM/STEM at 300 keV with a liquid Nitrogen sample holder.

The use of charging effects in Al/Al2O3 metal matrix composite materials as contrast mechanism in the SEM

1990 ◽  
Vol 48 (4) ◽  
pp. 422-423
Author(s):  
Andreas M. Borchert
Keyword(s):  
Secondary Electron ◽  
Aluminum Matrix ◽  
Interfacial Structure ◽  
Resolving Power ◽  
Coated Sample ◽  
Material Combination ◽  
Uncoated Sample ◽  
Backscattered Electrons ◽  
Contrast Mechanism ◽  
Good Contrast

In Al/Al2O3 MMC's the metal/ceramic interfacial structure is of great concern because aluminum does not wet (i.e. bond) well to alumina. One proposed method to overcome this problem is to form a magnesium-rich spinel (MgAl2O4) as an additional phase between the aluminum matrix and the alumina particle. The spinel forms by diffusion of Mg from the matrix and improves the bonding. Typically the SEM would be the most suitable instrument to study the spinel, but this particular material combination (alumina/spinel) does not have sufficient secondary or backscattered electron contrast to allow for normal imaging. The purpose of this work was to develop a technique for examining the growth and morphology of this spinel at the Al/Al2O3 interface. Samples of an Al/Al2O3 MMC with a spinel at the particle interface were prepared according to standard metallographic procedures. Certain samples were sputter coated with a gold film of approximately 12 nm thickness; other samples were examined uncoated. Nonconductive, uncoated specimens charge under the incident electron beam if the accelerating voltage is below E1 or above E2 in Figure 1. In both of cases (below E1 and above E2) the number of electrons entering the sample is higher than the number of electrons leaving the sample. The resolving power of the SEM is usually degraded by this effect and therefore nonconductive specimens are coated with a layer of conductive material prior to observation. Figure 2 shows how this effect can create contrast between two materials due to its effect on the secondary electron detector bias voltage. Figure 3 shows that this contrast mechanism exists for the material combination alumina/spinel. The secondary electron image of a coated sample (3a) shows almost no contrast between alumina and spinel whereas the uncoated sample (3b) shows good contrast due to the different charging characteristics of the materials. The alumina charges stronger than the spinel and appears brighter in the image. The assumption that the effect is due to secondary electrons is supported by Figure 4. The micrograph in Figure 4a was obtained by backscattered electrons only and shows poor contrast whereas the micrograph in Figure 4b was obtained by secondary and backscattered electrons and shows good contrast. Figure 5 shows micrographs obtained at different operating voltages. The reduction in contrast at lower operating voltages is due to reduced charging.

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