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).

Research highlights
► We prepared the three types of Pt-Co nanocatalysts by using different conditions.
► The Pt-Co nanocatalysts have the core-shell structure.
► The active surface coverage increases the alloying degree of Pt-Co catalysts.