Anodic electrodeposition of conducting cobalt oxyhydroxide films on a goldsurface. XPS study and electrochemical behaviour in neutral and alkaline solution

A novel chemically modified electrode prepared by anodic electrodeposition of cobalt (III) film on the gold electrode substrate (Au-Co) was characteri sed by cyclic voltammetry and XPS techniques in both neutral and alkaline m edium. Cobalt oxyhydroxide film was deposited by cycling the potential betw een 0.0 and 1.1 V versus SCE in 0.1 M sodium acetate solutions containing 1 0 mM CoCl2. The electrocatalytic properties of the Au-Co electrode were inv estigated in alkaline medium using glucose as a model compound. A comparati ve XPS study of bare gold, bare cobalt and Au-Co electrodes after electroch emical treatment in neutral and alkaline solutions has been carried out. A detailed XPS analysis of the Au4f(7.2), Co2p(3.2), O1s and C1s regions was performed to check the chemical composition of the Au-Co electrode upon ele ctrochemical treatments. Film deposition is attributed to growth of conduct ing and compact CoOOH oxyhydroxide with significant insertion of carbonyl g roups within the electrodeposited layer. The prolonged electrochemical trea tment in alkaline medium produces a good stabilization of the Co-III oxyhyd roxide film, with a dominant O1s feature at about 532.4 eV of BE correspond ing to a non-stoichiometric surface oxygen. The absence of CoO species prov es good conducting properties of the cobalt film and the absence of any pas sivation effects on the catalytic performance. (C) 1999 Elsevier Science S. A. All rights reserved.