The importance of the active states of surface atoms with regard to the electrocatalytic behaviour of metal electrodes in aqueous media

There is increasing independent evidence, e.g. from the application of surface enhanced Raman spectroscopy (SERS) and contact electrical resistance (CER) techniques that the behaviour of metal/aqueous solution interfaces is more complicated than is generally realised. It is demonstrated in the present work, for three different electrode systems (copper in base and platinum and gold in acid), that metal surfaces may be activated, i.e. the lattice energy in the outer layers of the metal may be reduced, by severe cathodic or thermal pretreatment. The redox behaviour of the resulting metastable, or non-equilibrium, surface states were investigated using cyclic voltammetry. It is suggested, on the basis of both the present and earlier work in this laboratory, that such surface states are of importance in electrocatalysis as they reflect the behaviour of active sites present at conventional electrode surfaces. (C) 2000 Elsevier Science Ltd. All rights reserved.