Indirect electrochemical reactions

The prime requirements for the separators in alkaline storage batteries are on the one hand to maintain durably the distance between the electrodes, and on the other to permit the ionic current flow in as unhindered a manner as possible. Since the electrolyte participates only indirectly in the electrochemical reactions, and serves mainly as ion-transport medium, no excess of electrolyte is required, i.e., the electrodes can be spaced closely together in order not to suffer unnecessary power loss through additional electrolyte resistance. The separator is generally flat, without ribs. It has to be sufficiently absorbent and it also has to retain the electrolyte by capillary forces. The porosity should be at a maximum to keep the electrical resistance low (see Sec. 9.1.2.3) the pore size is governed by the risk of electronic shorts. For systems where the electrode substance... 

Electrogenerated chemiluminescence (ECL) is the process whereby a chemiluminescence emission is produced directly, or indirectly, as a result of electrochemical reactions. It is also commonly known as electrochemiluminescence and electroluminescence. In general, electrically generated reactants diffuse from one or more electrodes, and undergo high-energy electron transfer reactions either with one another or with chemicals in the bulk solution. This process yields excited-state molecules, which produce a chemiluminescent emission in the vicinity of the electrode surface. 

In the cation pool method organic cations are generated by low temperature electrochemical oxidation of their precursors. Because electrochemical reactions take place only on the surface of the electrode, the accumulation of cations usually takes several hours. Therefore, the applicability of the method strongly depends on the stability of the cation that is accumulated. In order to solve this problem, we have developed a sequential one-pot indirect method, in which an active reagent is generated and accumulated electrochemically (step 1), and is subsequently allowed to react with a precursor to generate a cation pool (step 2). The cation pool thus-generated is allowed to react with a nucleophile (step 3).36... 

As mentioned above, the critical feature of indirect electrochemical reactions is the correct choice of a redox system. Specific examples of indirect electrochemical reactions with a great variety of redox carriers are presented in the following sections. 

Indirect electrochemical reactions usually involve a multi-electron-transfer system that consists of a set of electron transmission units (Fig. 4). Although the overall feature of an electron-transfer process in indirect electrosynthetic reactions is understandable, each step of the electron transmission has not yet been elucidated [10]. 

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