Preparation of Pt-Co nanocatalysts on carbon nanotube electrodes for direct methanol fuel cells

The electrochemical activities of three types of Pt-Co/CNT catalysts, prepared from different Co depositions, in methanol oxidation have been investigated. X-ray diffraction reveals that these Pt-Co/CNT catalysts possess not only different crystalline sizes but also different levels of atomic distribution. The use of strong reducing agent (NaBH4) enables the formation of a cobalt layer over the Pt surface, inducing bimetallic Pt-Co particles, whereas direct thermal reduction enables the formation of Pt-Co nanoalloy with a high degree of alloying. It has been shown that the normalized active surface coverage increases the alloying degree of Pt-Co catalysts, indicating the importance of atomic distribution. Cyclic voltammetric measurement also reveals that the Pt-Co/CNT catalyst with a good alloying degree exhibits a better electrochemical activity, high CO tolerance, and long-term durability (>100 cycles). (C) 2011 Elsevier BM. All rights reserved.