Electrolysis competing electrode reactions

Competing electrode reactions may occur. In the electrolysis of molten sodium chloride with inert electrodes, only one oxidation and one reduction are possible. 

Reaction 6 may involve an [H-H]+(ads) intermediate. The hydrogen electrode reactions are of interest from the standpoint of hydrogen-consuming fuel cells, competing reactions in various battery systems, the generation of hydrogen gas by water electrolysis, and the complementary cathodic reaction in metal corrosion in aqueous environments. The predominant pathway and rate-determining steps have been identified on a few metal electrode surfaces (30). 

The propanedioate (malonate) carbanion can be oxidized directly at an anode to give ethanetetracarboxylate esters, presumably via a radical intermediate.2-4 Competing oxidation of solvent leads to a mixture of products3,4 and for preparative purposes it is advantageous to carry out the reaction via indirect electrolysis as reported here. Indirect electrolysis refers to the continuous generation and regeneration of a reagent at an electrode, which inter-... 

When chloride ions are added to the MeCN solution of Ph3As, the oxidation of Ph3As on a Pt electrode takes place at a much lower potential (negative shift 0.8 V) than the direct oxidation of Phj As alone, and also at a lower potential than oxidation of Cl alone under the same conditions . This behaviour has been described as an electrocatalytic process involving initial oxidation of CC (reaction 99) followed by a fast reaction between Cr and Ph3 As (reaction 100), where the initial reaction between Cl and Phj As successfully competes with the formation of CI2 which is not formed during the electrolysis . ... 

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