Xh. Xia, New insights into the influence of upd Sn on the oxidation of formic acid on platinum in acidic solution, ELECTR ACT, 45(7), 1999, pp. 1057-1066
The influence of a stabilized submonolayer of upd tin adatoms on the oxidat
ion of adsorbed and bulk formic acid on sputtered platinum electrodes in 0.
1 M HClO4 has been investigated by measuring simultaneously the rate of CO2
production from both adsorbed and bulk formic acid. The use of on-line MS
technique (DEMS) enables us to distinguish the volatile products (CO2) form
ed in the oxidation of adsorbed and bulk species, respectively, with the he
lp of isotope-labeled C-13-formic acid as a probe. A considerable promoting
effect of upd tin adatoms on the oxidation of the bulk formic acid was obs
erved. This catalytic activity depends strongly on the coverage of the tin.
On the other hand, the oxidation of the formic acid adsorbate is accelerat
ed significantly in presence of Sn adatoms on the surface or tin ions in so
lution. Based on our results, a discrimination between the electrocatalytic
models of tin adatoms postulated in literature was given. We suggested tha
t a combination of a bifunctional mechanism and an electronic interaction b
etween the upd Sn adatoms and Pt substrate could account for the pronounced
catalytic influence on the oxidation of formic acid. (C) 1999 Elsevier Sci
ence Ltd. All rights reserved.