Multilayer hydrous oxide growth on copper in base and its correlation withpreviously reported electrocatalytic data for this electrode system

A repetitive potential cycling procedure was used to produce a specific mul tilayer hydrous oxide film on copper in base at 60 OC. Such a deposit under goes reduction in a quasi-reversible manner at ca. -0.1V (RHE), i.e. at a p otential that is unrelated to Pourbaix data for copper but, as demonstrated previously, is of major significance with regard to the electrocatalytic b ehaviour of this electrode system. In accordance with the incipient hydrous oxide/adatom mediator model of electrocatalysis, an active surface state o f the metal (Cu*) is assumed to be involved both in electrocatalysis and as a primary product in the hydrous oxide reduction reaction. While the latte r process occurs very rapidly at -0.1 V, it is not usually reversible as it is accompanied by subsequent rapid loss of the active state of the metal. The same general approach was used previously to explain the hydrous oxide and electrocatalytic behaviour of a range of noble metals.