Fabrication of bimetallic Pt-M (M = Fe, Co, and Ni) nanoparticle/carbon nanotube electrocatalysts for direct methanol fuel cells

The electrochemical activities of three bimetallic Pt-M (M = Fe, Co, and Ni) catalysts in methanol oxidation have been investigated. An efficient approach including chemical oxidation of carbon nanotubes (CNTs), two-step refluxing, and Subsequent hydrogen reduction was used to thoroughly disperse bimetallic nanopartilces on the oxidized CNTs. Three catalysts with a similar Pt:M atomic ratio, Pt-Fe (75:25). Pt-Co (75:25). and Pt-Ni (72:28), were prepared for the investigation of methanol oxidation. The Pt-M nanoparticles with an average size of 5-10 nm are uniform and cover the surface of CNTs. Cyclic voltammetry showed that the three pairs of catalysts were electrochemically active in the methanol oxidation. On the basis of the experimental results, the Pt-Co/CNT catalyst has better electrochemical activity, antipoisoning ability, and long-term cycleability than the other electrocatalysts, which can be justified by the bifunctional mechanism of bimetallic catalysts. The satisfactory results shed some light on how the use of Pt-Co/CNT composite could be a promising electrocatalyst for high-performance direct methanol fuel cell applications. (C) 2008 Elsevier B.V. All rights reserved.