291 J. Electroanal. Chem., 295 (1990) 291-300 Elsevier Sequoia S.A., Lausanne zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Cyclic voltammetric characterization of oriented monocrystalline gold surfaces in aqueous alkaline solution Antoinette Hamelin * Laboratoire d’Electrochimie Interfaciale du C. N. R S., I, Place A. Brian4 92195 Meudon (France) M.J. Sottomayor and F. Silva Department of Chemistry, University of Porte, 4ooO Port0 (Portugal) Si-Chung Chang and Michael J. Weaver * Department of Chemistty, Purdue University, West Lafayette, IN 47907 (U.S.A.) (Received 14 May 1990; in revised form 2 July 1990) ABSTRACT Monocrystalline gold surfaces having five different crystallographic orientations have been char- acterized by means of cyclic voltammetry in aqueous 0.11 M NaOH in order to examine the electrochem- istry of oxide formation and removal in comparison with the well-characterized behavior in acidic media. For the higher-index faces Au(210) and (311), these voltammetric features in 0.11 M NaOH are closely similar to those observed in acidic electrolytes, although the occurrence of substantial OH- adsorption is signaled by a broad reversible current-potential feature at less positive potentials. For the low-index faces Au(100) and (ill), however, the voltammograms in 0.11 M NaOH differ substantially from those in acid. These differences are ascribed to the influence of potential-dependent OH- adsorption, which overlaps with oxide formation and especially reduction, and attendant potential-induced surface reconstruction. The behavior of Au(l10) is intermediate between that of these other two low-index and the higher-index faces. As for the voltamrnetric features in acidic electrolytes, such crystal face-dependent voltammetry in 0.11 M NaOH can be employed as a sensitive (albeit empirical) check of the chemical and physical state of the interface prior to other electrochemical measurements. INTRODUCTION The use of cyclic voltammetry (CV) to characterize the nature of, and processes occurring on, monocrystalline gold surfaces is well established. (A representative list of citations is refs. 1-7). Besides the negative potential limit associated with hydrogen evolution, particularly informative are the voltammetric morphologies l To whom correspondence should be addressed. 0022-0728/90/$03.50 0 1990 - Elsevier Sequoia S.A.