Electrochemistry higher oxidation states

Subsequent investigations were undertaken of cobalt corroles with modified structures [77] and with cobalt in higher oxidation states [78]. In addition, cobalt-containing corrole dimers were studied [79], cobalt biscorroles were investigated ]80, 81], the influence of various alkyl and aryl substituents on the electrochemical behavior of cobalt corroles was probed ]82], and the effects of solvents on the electrochemistry of these compounds was examined [83]. 

Oxidation. Oxidation is a process that involves the transfer of one or more electrons. This can be carried out by adding an oxidizing agent or via electrochemistry. This process is used for the detoxification of hazardous waste the oxidation of cyanide to cyanate, and further decomposition into CO2 and N2 is a good example. Metals can be oxidized to their higher oxidation state, thus making them insoluble and recoverable as a precipitate. 

McBreen comprehensively reviewed nickel hydroxide battery electrodes, the solid state chemistry of nickel hydroxides, and the electrochemical reactions of the Ni(OH)21 NiOOH couple. Any critical discussion of the thermodynamic data of nickel oxide hydroxides with higher oxidation states has to refer to this splendidly written account of nickel solid state electrochemistry. 

Compounds containing silver at the oxidation states higher than I were not reviewed in the earlier edition of Encyclopedia of Electrochemistry. Therefore, it seems reasonable to fill this gap with some fundamental information on the electrochemistry of such species and an account of recent achievements made therein. 

As a consequence of the strong interrelationship between PANI s optical properties and its redox chemistry, PANl possesses polyelectrochromic abilities. In strongly acidic electrolytes, PANl that is doped with small-molecule acids can stably and reversibly switch between its green ES and transparent LB forms at higher pH, PANI s ES state is dedoped to EB and the material s electroactivity is lost. Transitions from ES to the purple PB form of PANl involve the loss of protons and thus their electrochemistry is pH dependent. In the acidic media required to stabilize switching between ES and LB, however, the oxidation potential required to access PB is beyond the PANI s degradation... 

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