Thermodynamic aspects of metal oxide electrodes

An oxide electrode in equilibrium with the aqueous solution is a multicomponent system with metal, oxygen, and hydrogen ions in both places. At constant water activity, the system can be considered as quasi-binary [31]. Oxide electrodes can be regarded simultaneously as oxygen electrodes and as metal electrodes [31-33]. The electrode potential of MO in contact with aqueous electrolyte can be expressed with respect to oxygen by 

Aspects of the thermodynamic pH dependence of the oxide electrode potential with x in non-stoichiometric oxides M02Hx have been discussed by Pohl and Atlung [35]. 

Ion and electron transfer reactions at metal oxide electrodes 

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