On the Underpotential Deposition of Tin on Platinum in Acid Solution

Stefenel, M. M.; Chierchie, T.; Mayer, C.

doi:10.1524/zpch.1983.135.135.251

Cited by 9 publications

(1 citation statement)

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“…41,42 Sn adatoms have long been known to inhibit H adsorption onto Pt, thus suppressing the hydride adsorption waves in the Pt cyclic voltammogram in aqueous acid. [43][44][45] In our catalysts, the Sn source is Sn(0) from the bulk of the electrodeposited electrodes or from the Sn structures in the microfabricated samples. However, inhibition of H or organic adsorption onto Pt is presumably accomplished by oxidized Sn, because redistribution of Sn to Pt background regions in the microfabricated catalysts is accompanied by a dramatic increase in the O signal on these regions in the Auger analysis (Figure 2), and Sn is present in an oxidized state at the surface of the electrodeposited catalysts, as determined by XPS.…”

Section: Resultsmentioning

confidence: 99%

Pt−Sn Microfabricated Surfaces as Catalysts for Organic Electro-oxidation

2001

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Microfabrication techniques have been used to prepare electrode surfaces reproducibly with well-defined composition and active area. Characterization of surfaces thus prepared leads to straightforward compositionactivity and structure-activity relations. Conventional ebeam deposition/lift-off techniques were used to fabricate the catalysts from a photopatterned resist on Pt. Catalysts consist of an array of closely spaced microstructures (circles or squares, 0.1 µm thick, 10-200 µm wide) of Sn on Pt. Characterization of these structures by Auger electron spectroscopy shows that the Pt areas are relatively rich in C, whereas the Sn is relatively rich in O, before and after exposure to aqueous solutions containing the organic fuel. After 3-5 min of use in 0.5 M H 2 SO 4 /MeOH, at potentials at which fuel oxidation occurs, redistribution of Sn to the Pt regions was observed. Sn redistribution on the time scale of the experiments is inhibited by capping the Sn with a Pt layer. In samples with capped Sn squares, the length of the Pt-Sn contact line was varied by changing the size of the structures while the exposed area of the electrode was kept constant. The activity of the capped Pt-Sn structures depends linearly on the Pt-Sn contact edge length. Thus, it is possible to confine the catalytic area of Pt-Sn electrodes by working with the appropriate structure design. The catalytic area of microfabricated Pt-Sn is located in the zone of intimate contact between the Pt and the Sn layers.

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