Double cathode structure

This flux will be dependent upon the surface vacancy concentration, the surface electron concentration, and the dissociation rate of the dioxygen molecule however, at present, the rate-limiting step has yet to be identified. Kilner et al. [11] have derived a simple relationship for the surface exchange coefficient in terms of the bulk and surface vacancy concentrations, in an attempt to explain the apparent correlation found between the activation enthalpy for the surface exchange coefficient and the diffusion coefficient, in a number of La-based perovskites. Adler et al. [12] have also arrived at a similar relationship for k, by consideration of the AC electrode behavior of symmetrical cells with a double cathode structure. As already mentioned, the exact mechanisms of oxygen surface exchange remain elusive however, the vacancy concentration is clearly a very important parameter. 

First, a single HTL was used in a simple anode/HTL/ETL/cathode structure. Aromatic amines, N, A -diphenyl-fV, AE-bis(3-methylphenyl)-l, L-biphenylM, A-diamine (TPD),32 and TPAC31 were widely used. Instead of a single HTL as mentioned in Section 2.4, however, it was revealed that the formation of double HTLs, HTL-A, and HTL-E, as shown in Fig. 2.6 became indispensible for high-performance OLEDs. It is required that the Ip of HTL-A should be similar to that... 

After this fitting procedure, Bode plots and Nyquist plots were generated. Comparisons were made with experimental samples of 100 nm thin film polycrystalline YSZ, and a close match was observed among the experimental Nyquist plots (taken at 336°C) and the simulated Nyquist plots (taken at 400°C), with moderate deviations found at low frequencies (see Figure 2). In addition to this information, details about the double-layer structure at the anode and cathode (as a... 

SendaA, MatsumotoK, NohiraT, HagiwaraR (2010) Effects of the cathodic structures of fluorohy-drogenate ionic Uquid electrolytes on the electric double layer capacitance. J Power Sources 195 4414-4417... 

Practice has shown that in systems with high potential (magnesium) sacrificial anodes, the flow of polarizing current is mainly controlled by the number and dimensions of the anodes, while in the case of the application of low potential sacrificial anodes (zinc and aluminum), the type and state of the cathode (structure) is the controlling factor. This means that doubling of... 

As we have discussed in Chapter 5, the electrical double layer, as depicted in Figure 7.1, plays a critical role in the distribution of electrical potential at the electrode-electrolyte interfaces and to the ion transport through the electrolyte from the anode side to the cathode side. Figure 7.1 shows the comprehensive details of the electrical double layer structure, which is composed of an inner Helmholtz plane (IHP), an outer Helmholtz plane (OHP), and the diffusion layer. 

Q.J. Zhou, T.M. He, Y. Ji, SmBaCo205+x double-perovskite structure cathode material for intermediate-temperature solid-oxide fuel cells. J. Power Sources 185, 754—758 (2008)... 

If the electrolyte components can react chemically, it often occurs that, in the absence of current flow, they are in chemical equilibrium, while their formation or consumption during the electrode process results in a chemical reaction leading to renewal of equilibrium. Electroactive substances mostly enter the charge transfer reaction when they approach the electrode to a distance roughly equal to that of the outer Helmholtz plane (Section 5.3.1). It is, however, sometimes necessary that they first be adsorbed. Similarly, adsorption of the products of the electrode reaction affects the electrode reaction and often retards it. Sometimes, the electroinactive components of the solution are also adsorbed, leading to a change in the structure of the electrical double layer which makes the approach of the electroactive substances to the electrode easier or more difficult. Electroactive substances can also be formed through surface reactions of the adsorbed substances. Crystallization processes can also play a role in processes connected with the formation of the solid phase, e.g. in the cathodic deposition of metals. 

The Ba.C) N, nanotubes and fullerene-like structures have been synthesized by various laboratories in recent years. The most popular method is the plasma arc technique. The first report on the synthesis of BN nanotubes was by Zettl and coworkers (55). Since BN is an insulator, a composite anode was prepared from a tungsten rod with an empty bore in the center, which was stuffed with a pressed hexagonal BN powder. For the cathode, a water-cooled Cu rod was used. The collected gray soot contained limited amount of multi wall BN nanotubes. It is possible that in this case, the tungsten serves also as a catalyst. By perfecting this method, macroscopic amounts of double-wall BN nanotubes of a uniform diameter (2 nm)... 

The flow-through cathode is the result of a tailored-to-the-process evolution of the GDE structure, which is available also in two additional configurations double-sided (originally developed for fuel cell servicing) and single-sided (see Fig. 9.7). The double-sided type is particularly suited for the electrochemical process where the product should not be released on to the back surface of the cathode, as in the case of oxygen-depolarised chlor-alkali electrolysis, discussed in Section 9.3. 

Figure 12. Voltage levels in the various sections of the unit cell of a battery, fuel cell, or electrochemical capacitor. The structure and composition of the electrical double layer differ at the anode and cathode.

A single-chamber solid oxide fuel cell (SC-SOFC), which operates using a mixture of fuel and oxidant gases, provides several advantages over the conventional double-chamber SOFC, such as simplified cell structure with no sealing required and direct use of hydrocarbon fuel [1, 2], The oxygen activity at the electrodes of the SC-SOFC is not fixed and one electrode (anode) has a higher electrocatalytic activity for the oxidation of the fuel than the other (cathode). Oxidation reactions of a hydrocarbon fuel can... 

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