A. Aramata et al., UNDERPOTENTIAL DEPOSITION OF ZINC IONS ON POLYCRYSTALLINE PLATINUM - FTIR AND EQCM STUDY, Electrochimica acta, 41(5), 1996, pp. 761-766
Underpotential deposition(UPD) of Zn(2+)ions on polycrystalline platin
um in KH2PO4 solution (pH 4.6) was studied by Fourier transform infrar
ed reflection spectroscopy (FTIR) and electrochemical quartz crystal m
icrobalance (EQCM). By the addition of Zn2+ ions in KH2PO4 solution, t
he intensities of ir bands of around 990, 1044 and 1090 cm(-1) are inc
reased with a negative increase of potentials at E less than or equal
to 0.7 V (the) where Zn UPD takes place, while by EQCM the weight incr
ease of Pt mounted quartz was observed in the same potential region. C
overage of UPD Zn was 0.75 at 0.05 V as two-electron transfer UPD proc
ess, being estimated from cyclic voltammogram, and mps (mass number pe
r platinum sites) was 78 by EQCM; from both values the coverage of pho
sphate was evaluated as 0.27. These results are discussed that the pho
sphate species adsorbs over UPD Zn on Pt as a form of HPO4, where one
of three P-O's seems to be bound to UPD Zn on Pt.