Ml. Foresti et al., BROMIDE ELECTROSORPTION ON THE LOW-INDEX FACES OF SILVER, Journal of the Chemical Society. Faraday transactions, 92(20), 1996, pp. 3747-3756
Citations number
37
Categorie Soggetti
Chemistry Physical","Physics, Atomic, Molecular & Chemical
Bromide adsorption on the three low-index faces of silver was investig
ated from mixed c mol dm(-3) KBr+(0.02-c) mol dm(-3) KPF6 solutions ov
er a range of c from 1x10(-6) to 5x10(-3) mol dm(-3) using the potenti
al-step chronocoulometric technique. The adsorption behaviour on the A
g(110) face shows significant differences with respect to that on the
Ag(111) and Ag(100) faces. Thus, the plot of the applied potential E v
s. the specifically adsorbed charge density sigma(i) of the bromide io
ns, for sigma(i) equal and opposite to the charge density sigma(M) on
the metal, shows a rather abrupt decrease in slope with a decrease in
sigma(i). Moreover, the plots of sigma(i) vs. sigma(M) at constant c i
ntersect for sigma(i)-35 mu C cm(-2). This behaviour is explained by a
decrease in the negative value of the surface potential due to electr
on smoothing with an increase in /sigma(i)/ on Ag(110). The potential
difference across the inner layer, once plotted against /sigma(i)/ at
constant sigma(M), attains a maximum value before shifting linearly to
wards more negative values with a further increase in /sigma(i)/; this
behaviour, observed on all three low-index faces, is interpreted on t
he basis of a molecular model of the inner layer which accounts for th
e reorientation of the water dipoles and for the screening by the inho
mogeneous electron gas.