Electrode interphase

Nanbu, N., Sasaki, Y., and Kitamura, R, In situ FT-IR spectroscopic observation of a room-temperature molten salt gold electrode interphase, Electrochem. Commun., 5,383-387,2003. 

Figure 5.1 Schematic representation of an electrochemical cell (a) three electrodes (b) equivalent circuit for three-electrode cell (c) equivalent circuit for the working-electrode interphase (d) a solution impedance in series with two parallel surface impedances.

An equivalent circuit of the three-electrode cell discussed in Chapters 6 and 7 is illustrated in Figure 9.1. In this simple model, Rr is the resistance of the reference electrode (including the resistance of a reference electrode probe, i.e., salt bridge), Rc is the resistance between the reference probe tip and the auxiliary electrode (which is compensated for by the potentiostat), Ru is the uncompensated resistance between the reference probe and the working-electrode interphase (Rt is the total cell resistance between the auxiliary and working electrodes and is equal to the sum of Rc and Ru), Cdl is the double-layer capacitance of the working-electrode interface, and Zf is the faradaic impedance of the electrode reaction. 

The effectiveness of the anodic treatment at BDD was also tested with an insoluble dye-like dispersed indigo (Bechtold et al. 2006), a typical dye used for cotton work clothes and blue jeans. Also in this case the treatment was effective leading to the complete decolourisation of the solution. The current yield was found to decrease with the applied current indicating a direct oxidation at the electrode interphase under diffusive control. The addition of NaCl up to 144mgL 1 did not enhance the rate of the decolourisation, as well as persulphate, eventually formed from sulphate present in the supporting electrolyte, resulted ineffective. 

The transfer of electric charge across the solution/electrode interphase is accompanied by an electrochemical reaction at each electrode (electrolysis). We must keep the phenomenon in the bulk of the solution separate from the phenomenon at the electrodes. 

Jossinet, J., McAdams, E.T., 1991. The skin/electrode interphase impedance. Innov. Technol. Biol. Med. 12 (1), 22-31. 

On the other hand, this technique has a shortcoming it is necessary to chemically fix the gel onto the electrode surface. Therefore, the swelling and shrinking of the gel is not isotropic and one side is restricted. A question also remains as to whether the structure of the gel at the electrode interphase is the same as in the bulk. 

McIntyre, J.D.E. (1973) Specular reflection spectroscopy of the electrode-interphase. In Advances in Electrochemistry and Electrochemical Engineering, Optical Techniques in Electrochemistry, Vol. 9 (ed R.H. Muller), John Wiley Sons, Inc., New York, pp. 61-166. 

Under certain conditions, it will be impossible for the metal and the melt to come to equilibrium and continuous corrosion will occur (case 2) this is often the case when metals are in contact with molten salts in practice. There are two main possibilities first, the redox potential of the melt may be prevented from falling, either because it is in contact with an external oxidising environment (such as an air atmosphere) or because the conditions cause the products of its reduction to be continually removed (e.g. distillation of metallic sodium and condensation on to a colder part of the system) second, the electrode potential of the metal may be prevented from rising (for instance, if the corrosion product of the metal is volatile). In addition, equilibrium may not be possible when there is a temperature gradient in the system or when alloys are involved, but these cases will be considered in detail later. Rates of corrosion under conditions where equilibrium cannot be reached are controlled by diffusion and interphase mass transfer of oxidising species and/or corrosion products geometry of the system will be a determining factor. 

The Stern model (1924) may be regarded as a synthesis of the Helmholz model of a layer of ions in contact with the electrode (Fig. 20.2) and the Gouy-Chapman diffuse model (Fig. 20.10), and it follows that the net charge density on the solution side of the interphase is now given by... 

Kinetic stability of lithium and the lithiated carbons results from film formation which yields protective layers on lithium or on the surfaces of carbonaceous materials, able to conduct lithium ions and to prevent the electrolyte from continuously being reduced film formation at the Li/PC interphase by the reductive decomposition of PC or EC/DMC yielding alkyl-carbonates passivates lithium, in contrast to the situation with DEC where lithium is dissolved to form lithium ethylcarbonate [149]. EMC is superior to DMC as a single solvent, due to better surface film properties at the carbon electrode [151]. However, the quality of films can be increased further by using the mixed solvent EMC/EC, in contrast to the recently proposed solvent methyl propyl carbonate (MPC) which may be used as a single sol-... 

QCMB RAM SBR SEI SEM SERS SFL SHE SLI SNIFTIRS quartz crystal microbalance rechargeable alkaline manganese dioxide-zinc styrene-butadiene rubber solid electrolyte interphase scanning electron microscopy surface enhanced Raman spectroscopy sulfolane-based electrolyte standard hydrogen electrode starter-light-ignition subtractively normalized interfacial Fourier transform infrared... 

Techniques are described which obtain the IR absorption spectra of species, either adsorbed or free In the electrode/electrolyte solution Interphase. Applications slanted towards topics relevant to electrocatalytic processes are discussed to Illustrate the capabilities of the methods In probing molecular structure, orientation and Interactions. 

In principle, therefore, these valuable techniques can provide all of the information needed to specify the molecular structure of the electrode/electrolyte solution interphase, the dynamics of adsorption/... 

This review has been restricted mainly to clarification ofthe fundamentals and to presenting a coherent view ofthe actual state of research on voltaic cells, as well as their applications. Voltaic cells are, or may be, used in various branches of electrochemistry and surface chemistry, both in basic and applied research. They particularly enable interpretations of the potentials of various interphase and electrode boundaries, including those that are employed in galvanic and electroanalytical cells. 

The interphase between an electrode and an electrolyte solution has a very complex electrical structure (Section 10.1). In this interphase various adsorption processes take place ... 

Both the electrical structure of the interphase and the occurrence of adsorption processes have a great influence on electrochemical reactions on an electrode s surface and on various electrochemical phenomena. 

When an electrode is in contact with an electrolyte, the interphase as a whole is electroneutral. However, electric double layers (EDLs) with a characteristic potential distribution are formed in the interphase because of a nonuniform distribution of the charged particles. 

In the electrode-solution interphase, the adsorption of these substances is also affected by the influence of the electric field in the double layer on their dipoles. Substances that collect in the interphase as a result of forces other than electrostatic are termed surface-active substances or surfactants. 

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