H. Uchida et al., ELECTROCHEMICAL QUARTZ-CRYSTAL MICROBALANCE STUDY OF COPPER ADATOMS ON AU(111) ELECTRODES IN SOLUTIONS OF PERCHLORIC AND SULFURIC-ACID, Journal of electroanalytical chemistry [1992], 452(1), 1998, pp. 97-106
The adsorption of anions on highly ordered (111)-type gold electrodes
with and without Cu adatoms in perchloric and sulfuric acid electrolyt
e solutions was investigated on an electrochemical quartz crystal micr
obalance. A distinct increase in mass due to the specific adsorption o
f hydrated bisulfate and perchlorate anions was observed in Cu2+ -free
solutions and their amounts were determined as a function of the pote
ntial. The composition of the Cu-adlayer (theta(Cu) and theta(anion),
coverages of Cu adatoms and co-adsorbed anions) during formation or re
moval in the potential sweep was also determined in both electrolyte s
olutions. A pair of reversible anodic and cathodic peaks in the voltam
mogram for the first Cu-upd region in H2SO4 was found to correspond we
ll to the reversible changes in theta(Cu) and theta(anion). In contras
t, asymmetric features of the voltammograms for the second Cu-upd regi
on in H2SO4 and for whole processes in HClO4 corresponded to the large
hysteresis in changes of theta(Cu) and theta(anion), probably origina
ting from a slow rearrangement of both species. (C) 1998 Elsevier Scie
nce S.A. All rights reserved.