Electrolytic conductors oxidation

When electricity passes through a circuit consisting of both types of electrical conductors, a chemical reaction always occurs at their interface. These reactions are electrochemical. When electrons flow from the electrolytic conductor, oxidation occur at the interface while reduction occurs if electrons flow in the opposite direction. These electronic-electrolytic interfaces are referred to us electrodes, interfaces where oxidation occurs are known as anodes and those ai which reduction occurs, as cathodes. An anode is also defined as that electrode by which "conventional" current enters an electrolytic solution, a cathode as that electrode by which "conventional" current leaves. Positive ions, for example, ions of hydrogen and the metals, are called cations while negative ions, for example, acid radicals and ions of nonmctals. are called anions. 

Doped zirconia, yttria and thoria Other oxides (magnesia, alumina, etc.) Electrolytic conductor Nonconductors... 

Fig. 3. Oxygen transport in solids. 02 is dissociated and ionized at the reduction interface to give O2 ions, which are transferred across the solid to the oxidation interface, at which they lose the electrons to return back to 02 molecules that are released to the stream, (a) In the solid electrolyte cell based on a classical solid electrolyte, the ionic oxygen transport requires electrodes and external circuitry to transfer the electrons from the oxidation interface to the reduction interface (b) in the mixed conducting oxide membrane, the ionic oxygen transport does not require electrodes and external circuitry to transfer the electrons to the reduction interface from the oxidation interface, because the mixed conductor oxide provides high conductivities for both oxygen ions and electrons.

A sodium-ion conductor (Nasicon) is used as the solid electrolyte. Various oxides have been proposed for the auxiliary phase, depending on the target test gas, includ-... 

A fuel and an oxidizing gas are involved. The fuel is hydrogen which is oxidized at the anode according to the reaction H2 2H+ -I- 2e . Positive ions rrrigrate from the anode to the cathode through the electrolyte conductor... 

As an example of (ii), consider sodium oxide, NaaO, and potassium oxide, K2O. Since lithium oxide, Li20, is known to be a good electrolytic conductor in the liquid state, analogy suggests that Na20 and K2O should also be good electrolytic conductors in the liquid state, and therefore also salt-like. 

Figure 10.8. Schematic of a fuel cell for power generation (left) and its opposite, a reactor component for gas electrolysis (right). All components are solid the electrolyte is a nonporous, gas-impermeable oxide ion conductor (stabilized zirconia), and the electrodes are porous electron conductors (oxides and cermets).

The principle of detection is as follows. On the surface of the Ba-Ce-Y-O electrolyte, barium oxide exists as a result of the decomposition of the protonic conductor. Barium oxide reacts with water vapor in a humid atmosphere and forms barium hydroxide on the surface. This hydroxide absorbs carbon dioxide to form a carbonate, and as a result, the conductivity decreases. 

Solid Oxide Fuel Cell In SOF(7s the electrolyte is a ceramic oxide ion conductor, such as vttriurn-doped zirconium oxide. The conduetKity of this material is 0.1 S/ern at 1273 K (1832°F) it decreases to 0.01 S/ern at 1073 K (1472°F), and by another order of magnitude at 773 K (932°F). Because the resistive losses need to be kept below about 50 rn, the operating temperature of the... 

Electrochemistry plays an important role in the large domain of. sensors, especially for gas analysis, that turn the chemical concentration of a gas component into an electrical signal. The longest-established sensors of this kind depend on superionic conductors, notably stabilised zirconia. The most important is probably the oxygen sensor used for analysing automobile exhaust gases (Figure 11.10). The space on one side of a solid-oxide electrolyte is filled with the gas to be analysed, the other side... 

Since the realization in the early 1980s that poly (ethylene oxide) could serve as a lithium-ion conductor in lithium batteries, there has been continued interest in polymer electrolyte batteries. Conceptually, the electrolyte layer could be made very thin (5im ) and so provide higher energy density. Fauteux et al. [31] have recently reviewed the present state of polymer elec-... 

Today, the term solid electrolyte or fast ionic conductor or, sometimes, superionic conductor is used to describe solid materials whose conductivity is wholly due to ionic displacement. Mixed conductors exhibit both ionic and electronic conductivity. Solid electrolytes range from hard, refractory materials, such as 8 mol% Y2C>3-stabilized Zr02(YSZ) or sodium fT-AbCb (NaAluOn), to soft proton-exchange polymeric membranes such as Du Pont s Nafion and include compounds that are stoichiometric (Agl), non-stoichiometric (sodium J3"-A12C>3) or doped (YSZ). The preparation, properties, and some applications of solid electrolytes have been discussed in a number of books2 5 and reviews.6,7 The main commercial application of solid electrolytes is in gas sensors.8,9 Another emerging application is in solid oxide fuel cells.4,5,1, n... 

Nevertheless there are some reactions which never change. Thus NO reduction on noble metals, a very important catalytic reaction, is in the vast majority of cases electrophilic, regardless of the type of solid electrolyte used (YSZ or P"-A1203). And practically all oxidations are electrophobic under fuel lean conditions, regardless of the type of solid electrolyte used (YSZ, p"-Al203, proton conductors, even alkaline aqueous solutions). 

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