Carbon Monoxide Electro-oxidation Properties of Carbon-Supported PtSn Catalysts Prepared Using Surface Organometallic Chemistry

Abstract

A series of platinum-tin catalysts supported on carbon have been prepared from organometallic precursors using surface organometallic chemistry (SOMC). The catalysts were characterized using chemisorption, transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry. The addition of tin to Pt/C suppresses chemisorption of both hydrogen and carbon monoxide, with a rapid decrease on addition of just a small amount of tin, leveling off to give a plateau at higher loading. TEM, EDX, and XPS provide evidence that the platinum and tin occur together on the support and that on exposure to air the catalysts consist mainly of metallic platinum in association with tin oxide. A catalyst prepared using SOMC and another of similar loading prepared using conventional precipitation were compared for the electro-oxidation of adsorbed carbon monoxide using cyclic voltammetry. The catalyst prepared using SOMC showed enhanced activity with a larger decrease in the onset potential of carbon monoxide oxidation compared to Pt/C. Comparison of a range of carbon support platinum-tin catalysts with different loading prepared using SOMC showed a decrease in the onset potential for the catalyst at low loading with no further significant decrease in potential on addition of further tin. The peak intensities, however, changed significantly with an increase in loading.

The Effect of Sn Addition on a Pt∕C Electrocatalyst Synthesized by Borohydride Reduction and Hydrothermal Treatment for a Low-Temperature Fuel Cell

“…It appears that Sn has the ability to promote the oxidation of adsorbed CO at low potentials. 18 The shift of the onset potential on the 3Pt1Sn/C catalyst may be attributed to the presence of oxygenated species on the Sn sites at a lower potential as compared to the PtRu/C and Pt/C catalysts. [18][19][20] The superior activity of the 3Pt1Sn/C catalyst can be explained by a bifunctional mechanism.…”

“…[14][15][16] Recently, PtSn/C catalyst, which has been studied for the oxidation of methanol and ethanol, was used to promote the oxidation of both methanol and CO chemisorbed on the Pt sites. 5,6,[17][18][19][20] In previous works, PtSn/C catalyst synthesized by an impregnation and modified polyol method showed much higher activity than Pt/C catalyst. 17,21,22 In this study, a 20 wt % 3Pt1Sn/C catalyst was synthesized by borohydride reduction and hydrothermal treatment for use as the anode electrode of a low-temperature fuel cell.…”

Dynamic Behavior of a PEM Fuel Cell During Electrochemical CO Oxidation on a PtRu Anode

“…However, even traces (ppm) of carbon monoxide (CO) in the hydrogen feed gas can cause serious performance degradation of PEMFCs [1][2][3][4][5][6]. In order to achieve higher power output with CO containing feed in fuel cells, the utilisation of bimetallic anode catalysts, PtM/C, have been largely investigated [1][2][3][6][7][8][9][10][11][12]. The influence of Ru, Mo, Sn with Pt as anode catalyst is intensively studied.…”

Effect of SnO[sub 2] Deposition Sequence in SnO[sub 2]-Modified PtRu/C Catalyst Preparation on Catalytic Activity for Methanol Electro-Oxidation

“…The ratios of Sn in all the SnO 2 -modified PtRu/C catalysts were larger than the nominal ratio, which coincided with previously reported results. 33,34 Although the SnO 2 /PtRu/C catalyst has the largest surface ratio of Sn, the metal utilization, as listed in Table I, is still greater than that of the PtRuSnO 2 /C and PtRu/SnO 2 /C catalysts, also suggesting that the majority of SnO 2 particles in the SnO 2 /PtRu/C catalyst were just in contact with PtRu particles.…”