Metal-electrolyte interface schematic

Figure 2.1 (a) A schematic representation of the apparatus employed in an electrocapillarity experiment, (b) A schematic representation of the mercury /electrolyte interface in an electro-capillarity experiment. The height of the mercury column, of mass m and density p. is h, the radius of the capillary is r, and the contact angle between the mercury and the capillary wall is 0. (c) A simplified schematic representation of the potential distribution across the metal/ electrolyte interface and across the platinum/electrolyte interface of an NHE reference electrode, (d) A plot of the surface tension of a mercury drop electrode in contact with I M HCI as a function of potential. The surface charge density, pM, on the mercury at any potential can be obtained as the slope of the curve at that potential. After Modern Electrochemistry, J O M. 

Fig. 1. Schematic representation of the metal—electrolyte interface and reaction sites for outer-sphere (a, c) and inner-sphere (b) redox reaction paths at electrodes [12].

Figure 5.1 Schematic of a metal-electrolyte interface with an applied potential.

Figure 6.22 Schematic energy digram of a metal/electrolyte interface (a) and n-semiconductor/ electrolyte interface (b) for equilibrium 6) and deposition (ii) conditions., and denote...

FIGURE 4.4 Schematic representation of the Stem model of the stmcture of the double layer at the metal-electrolyte interface showing the ions and water moleeules. The inner and outer Helmholtz planes are labeled, along with the dilluse double layer. In the figure, the metal has been positively polarized. 

Fig. 5.8 - Schematic models of the ion, potential (0) and charge (a) distribution across the metal-electrolyte interface for (a) non-specific adsorption, (b) weak specific adsorption and (c) strong specific adsorption. 0, 0j, 02 0 re the...

FIGURE 1.12 Schematic of a simple outer-sphere one-electron transfer process at the metal/electrolyte interface. 

Figure 1.5. Schematic representation of a metal electrode deposited on a 02 -conducting (left) and on a Na -conducting (right) solid electrolyte, showing the location of the metal-electrolyte double layer and of the effective double layer created at the metal/gas interface due to potential-controlled ion migration (backspillover).

We start by considering a schematic representation of a porous metal film deposited on a solid electrolyte, e.g., on Y203-stabilized-Zr02 (Fig. 5.17). The catalyst surface is divided in two distinct parts One part, with a surface area AE is in contact with the electrolyte. The other with a surface area Aq is not in contact with the electrolyte. It constitutes the gas-exposed, i.e., catalytically active film surface area. Catalytic reactions take place on this surface only. In the subsequent discussion we will use the subscripts E (for electrolyte) and G (for gas), respectively, to denote these two distinct parts of the catalyst film surface. Regions E and G are separated by the three-phase-boundaries (tpb) where electrocatalytic reactions take place. Since, as previously discussed, electrocatalytic reactions can also take place to, usually,a minor extent on region E, one may consider the tpb to be part of region E as well. It will become apparent below that the essence of NEMCA is the following One uses electrochemistry (i.e. a slow electrocatalytic reaction) to alter the electronic properties of the metal-solid electrolyte interface E. 

Figure 5.17. Schematic representation of a metal crystallite deposited on YSZ and of the changes induced in its electronic properties upon polarizing the catalyst-solid electrolyte interface and changing the Fermi level (or electrochemical potential of electrons) from an initial value p to a new value p -eri30 31 Reprinted with permission from Elsevier Science.

Figure 7. A schematic representation of the microscopic model for the metal/electrolyte solution interface. Shown from top to bottom are an ion that is contact adsorbed with partial loss of its hydration shell, an ion whose hydration shell partially consists of first layer of water molecules, and an ion that is not contact adsorbed.

Figure 11.3. Schematic diagram showing the reactions that take place during Zn deposition via a Zn(OH)2 layer (A) metal-hydroxide interface (B) hydroxide-electrolyte interface. (From Electrochemically Deposited Thin Films II, M. Paunovic, ed., Electrochemical Society, Pennington, NJ, 1995, with permission from the Electrochemical Society.)...

It is the electrode potential

electrochemical experiments it represents a potential difference between two identical metallic contacts of an electrochemical circuit. Such a circuit, whose one element is a semiconductor electrode, is shown schematically in Fig. 2. Besides the semiconductor electrode, it includes a reference electrode whose potential is taken, conventionally, as zero in reckoning the electrode potential (for details, see the book by Glasstone, 1946). The potential q> includes potential drops across the interfaces, i.e., the Galvani potentials at contacts—metal-semiconductor interface, semiconductor-electrolyte interface, etc., and also, if current flows in the circuit, ohmic potential drops in metal, semiconductor, electrolyte, and so on. (These ohmic drops are negligibly small under experimental conditions considered below.)... 

Other aspects of the electrode-electrolyte interface must also be considered, such as specific adsorption of charged particles from the solution at the electrode and the formation of traps at the semiconductor surface. These aspects will be only schematically illustrated here. Fig. 1 shows several cases of electrode-electrolyte interfaces and points out the most important differences between metal and semiconductor electrodes. 

Let us consider the contact phenomena on the bonndary of the solid electrolyte-metal interface, schematically shown in Figure 1.11. In this case, the work function of electrons from the metal is bigger than the work function of electeons... 

Figure 4.1 Schematic of the atomic structure of the active three-phase interface between the metal particle that catalyzes the reaction, the carbon support necessary to conduct electrons, and the polymer electrolyte and solution necessary to conduct protons for electrocatalytic systems.

For in situ investigations of electrode surfaces, that is, for the study of electrodes in an electrochemical environment and under potential control, the metal tip inevitably also becomes immersed into the electrolyte, commonly an aqueous solution. As a consequence, electrochemical processes will occur at the tip/solution interface as well, giving rise to an electric current at the tip that is superimposed on the tunnel current and hence will cause the feedback circuit and therefore the imaging process to malfunction. The STM tip nolens volens becomes a fourth electrode in our system that needs to be potential controlled like our sample by a bipotentiostat. A schematic diagram of such an electric circuit, employed to combine electrochemical studies with electron tunneling between tip and sample, is provided in Figure 5.4. To reduce the electrochemical current at the tip/solution... 

Thus, it is interesting to note that high-purity aluminum rests at a potential at which corrosion is at its minimum and is, indeed, relatively very small. It is also largely independent of the anions present in the electrolyte.69 This may be attributed to the coulombic repulsion of anions away from the surface by the negative charge on the metal. The latter seems not to be completely compensated in a thin oxide film, as shown schematically in Fig. 9, so that the solution side of the double layer formed at the O/S interface contains excess cations, anions being repelled. The anions could approach the O/S interface either at thicker films or at potentials more positive than the OCP. 

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