Carbon monoxide electro-oxidation properties of carbon-supported PtSn catalysts prepared using surface organometallic chemistry

A series of platinum-tin catalysts supported on carbon have been prepared f rom organometallic precursors using surface organometallic chemistry (SOMC) . The catalysts were characterized using chemisorption, transmission electr on microscopy (TEM), energy dispersive X-ray analysis (EDX), X-ray photoele ctron spectroscopy (XPS), anti cyclic voltammetry. The addition of tin to P t/C suppresses chemisorption of both hydrogen and carbon monoxide, with a r apid decrease on addition of just a small amount of tin, leveling off to gi ve a plateau at higher lending. 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 prepar ed using conventional precipitation were compared for thr electro-oxidation of adsorbed carbon monoxide using cyclic voltammetry. The catalyst prepare d using SOMC showed enhanced activity with a larger decrease in the onset p otential of carbon monoxide oxidation compared to Pt/C. Comparison of a ran ge of carbon support platinum-tin catalysts with different loading prepared using SOMC showed a decrease in the onset potential for the catalyst at lo w loading with no further significant decrease in potential on addition of further tin. The peak intensities, however changed significantly with an in crease in loading. (C) 2000 The Electrochemical Society. S0013-4651(99)12-0 93-7. All rights reserved.