Da. Berg et al., UNDERPOTENTIAL DEPOSITION OF THALLIUM(I) ON ELECTROPOLISHED COPPER INAQUEOUS-SOLUTIONS, Journal of electroanalytical chemistry [1992], 355(1-2), 1993, pp. 165-179
The underpotential deposition (UPD) of thallium on electropolished cop
per electrodes was examined in aqueous solutions of chloride, perchlor
ate and sulphate base electrolytes. Two distinct UPD peaks were observ
ed and their respective charges of formation are reported. The depende
nce of the peak potential E(p), the peak pseudocapacitance C(p) and th
e peak half-width DELTAE1/2 for the first monolayer UPD peak were anal
ysed in detail according to the method proposed by Conway and coworker
s. The role of different anionic effects on the adsorption mechanism o
f formation of the first monolayer is described. Analyses of cyclic vo
ltammetry data and current-time transients obtained by potentiostatic
pulse techniques suggest that the second UPD peak is formed by an inst
antaneous nucleation and growth mechanism. Results of the pH effects o
n the main UPD peak of Tl on Cu are presented and it is shown that, at
high pH values, the formation of copper oxide/hydroxide does not hind
er the full monolayer underpotential deposition of thallium.