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

Abstract

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.

Scanning tunneling microscopy of Sn coadsorbed with Cu and CO on Pt(111) electrodes

“…PtSn composite materials have been widely studied as heterogeneous catalysts for the hydrocarbon conversion reaction, and as electro-catalysts for the direct oxidation of methanol, CO, and other C 1 compounds. Modification of the Pt surface by Sn can be achieved by the following methods: (1) electrochemical co-deposition of Pt and Sn as an alloy, 1,2 (2) underpotential deposition (UPD) of Sn, 3,4 and (3) alloy formation by annealing Sn-covered Pt surfaces. [5][6][7] It seems to be important to keep the preparation methods in mind when discussing the catalytic effects of Sn-Pt bimetallic materials; different PtSn composite catalysts show different electronic and structural properties, 8 therefore a marked influence on CO and methanol electro-oxidation is observed.…”

Electrodeposition of platinum metal on titanium and anodised titanium from P salt: Application to electro-oxidation of glycerol

“…In spite of the interest in small organic molecules, bigger molecules such as glycerol are important in both electrosyntheses and fuel cells technology. Despite the interest in this molecule, few studies concerning its electro-oxidation have been realised [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. A cyclic voltammetric study of the electrocatalytic oxidation of glycerol on gold and platinum electrodes in aqueous solution was performed by Kahyaoglu et al…”

Electrodeposition of Platinum and Ruthenium Nanoparticles in Multiwalled Carbon Nanotube‐Nafion Nanocomposite for Methanol Electrooxidation

“…Much effort has been made to develop Pt-based catalysts with higher CO poisoning tolerance and electrocatalytic activity. Improved electrocatalytic activity towards the methanol electrooxidation has been reported for Pt-based catalysts with other elements such as Ru [2], Sn [3], and Os [4,5]. Among these Pt-based catalysts, PtRu bimetallic catalyst has shown the best electrocatalytic activity towards the methanol electrooxidation.…”