Single-crystal nanowires of platinum can be synthesized by controlling the reaction rate of a polyol process

Platinum nanowires of ∼100 nm in length and 5 nm in diameter have been synthesized by reducing H2PtCl6 with ethylene glycol in the presence of poly(vinyl pyrrolidone) (PVP) and a trace amount of Fe3+ or Fe2+. The wires were generated at the final stage of the synthesis, which involved the formation of several intermediate species. The Fe3+ or Fe2+ ions had dual functions in the synthesis: they induced aggregation of Pt nanoparticles into larger structures that served as the nucleation sites, and they greatly reduced the reaction rate and supersaturation level to induce anisotropic growth. The reaction mechanism was studied by X-ray photoelectron spectroscopy (XPS) and UV-vis spectral analysis. The Pt nanowires could be readily separated from the surfaces of the agglomerates by sonication and obtained as pure samples by centrifugation. Copyright © 2003 American Chemical Society.