Electrochemical Decomposition of

Whereas the electrochemical decomposition of propylene carbonate (PC) on graphite electrodes at potentials between 1 and 0.8 V vs. Li/Li was already reported in 1970 [140], it took about four years to find out that this reaction is accompanied by a partially reversible electrochemical intercalation of solvated lithium ions, Li (solv)y, into the graphite host [64], In general, the intercalation of Li (and other alkali-metal) ions from electrolytes with organic donor solvents into fairly crystalline graphitic carbons quite often yields solvated (ternary) lithiated graphites, Li r(solv)yC 1 (Fig. 8) [7,24,26,65,66,141-146],... 

In practice, the decomposition potential for this overall reaction is found to be about 1.5 V this somewhat high value probably results from polarization and contact resistances. It could be seen that the electrochemical decomposition of alumina to deposit aluminum, using an inert anode, would require a theoretical cell voltage of 2.21 V as opposed to that of 1.18 V when carbon is used as the anode. Thus the participation of carbon in the cell reaction brings down the theoretically required cell voltage by almost 50%. 

It was concluded from the results that RP-HPLC methods can be successfully employed for the study of the electrochemical decomposition of textile dyes [149],... 

The second approach is an adaptation of the voltammetry technique to the working environment of electrolytes in an operational electrochemical device. Therefore, neat electrolyte solutions are used and the working electrodes are made of active electrode materials that would be used in an actual electrochemical device. The stability limits thus determined should more reliably describe the actual electrochemical behavior of the investigated electrolytes in real life operations, because the possible extension or contraction of the stability window, due to either various passivation processes of the electrode surface by electrolyte components or electrochemical decomposition of these components catalyzed by the electrode surfaces, would have been... 

In many cases, the difference between these potentials—the window of operation without electrochemical decomposition of the solvent—is 3-4 V. In the aqueous case, it may in practice be as little as 1.5 V. On the other hand, even sodium can be electrodeposited from a solution of sodium acetate in ethanolamine. These advantages are countered by three factors that must be considered before a nonaqueous electrodeposition process is chosen as the best solution to co-deposition of H (Section 4.8.3). 

The thermodynamic breakdown energy for water is 1.23 eV. The electrochemical decomposition of water requires two electrons in consecutive steps. 

Sonoyama N, Hara K, Sakata T. Reductive electrochemical decomposition of chloroform on metal electrodes. Chem Lett 1997 131-132. 

Sonoyama N, Sakata T. Electrochemical decomposition of CFC 12 using gas diffusion electrodes. Environ Sci Technol 1998 32 375-378. 

The theoretical voltage needed for electrochemical decomposition of chloride under the simultaneous formation of chlorate is calculated in the same way as has been used for hypochlorites. In a neutral solution (a0u- = 10 7) at a hydrogen pressure of pH, = 1 atm., the reduction potential at the cathode where reaction (XVII-10) occurs, will equal... 

Decomposition potential (voltage) — The onset voltage for electrochemical decomposition of the electrolytic solution or the electrodes. The decomposition can take place due to either oxidation or reduction, or both. The decomposition potentials define the electrochemical window of the system. Its value depends on the salt, solvent, electrode material, temperature, and the existence of materials that can catalyze decomposition reactions, such as Lewis acids. Exact decomposition voltages are hard to reproduce as the onset current of the process is very sensitive to the experimental conditions (e.g., scan rate, temperature, type of electrode, etc.). Decomposi-... 

Electrolyzer — Electrochemical cell used for electrolytic processes (-> electrolysis), i.e., the electrochemical decomposition of matter. 

Electrolysis of water — This is a process of electrochemical decomposition of water into -> hydrogen and -> oxygen. Apart from alkaline electrolyzers using 25% KOH solution [i], devices with polymer, or ceramic ion-conducting -> membranes have been developed for industrial applications [ii]. 

Corrosion—the gradual decay of materials—occurs in many ways, all involving electrochemical surface reactions. The essence of it is the electrochemical dissolution of atoms in the surface into the ion-containing film that is in contact with the corroding metal. However, such dissolution has to be accompanied by a counter-reaction and this is often the electrochemical decomposition of water to form hydrogen on the metal surface. If that occurs, the H in the form of minute protons, H, may enter the metal, diffuse about, and cause a weakening ofmetal-metal bonds and hence stress-corrosion cracking. 

Chemical electrodes Materials sensors, biosensors, electrochemical decomposition of organic materials, electrodes for organic synthesis... 

Figure 9 Change in the spectrum shown in Figure 8 when CO is adsorbed from electrochemical decomposition of methanol. The high-field intensity diminishes, and a rather sharp feature appears at low field.

The adsorption properties of carbon monoxide and CN generated by the electrochemical decomposition of C-enriched methanol or C-enriched NaCN have been studied using EC-NMR [129, 130]. The C NMR of the adsorbed species on Pt nanoparticles reveals that the potential control affects the NMR output to varying extents [142]. A positive potential change leads to the shielding of C resonances and slopes of the order of —71 ppm for CO (Figure 20.11) and —50... 

In NaCl solutions, one of the typical ECM electrolytes, the electrochemical decomposition of water with the formation of hydrogen gas is the only cathodic reaction ... 

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