NaBH4-assisted ethylene glycol reduction for preparation of carbon-supported Pt catalyst for methanol electro-oxidation

A carbon-supported Pt catalyst (40 wt.% loading) is prepared by a modified ethylene glycol reduction method (Pt–EG-complex). In this procedure, a complex produced by reacting ethylene glycol with sodium borohydride (NaBH4), serves as a reducing agent for the Pt precursor and as a stabilizer for preventing the growth of Pt particles. For purposes of comparison, two types of carbon-supported Pt catalyst (40 wt.% loading) are also prepared by a NaBH4 reduction method, in which the Pt precursor is reduced in a ethylene glycol solution (Pt–EG–NaBH4) and in de-ionized water (Pt–H2O–NaBH4). Analysis by X-ray diffraction and transmission electron microscopy reveal that the Pt–EG-complex catalyst is comprised of highly-dispersed Pt nanoparticles with a uniform size (2.9–3.1 nm) on the carbon support, while large Pt particles are observed in the Pt–EG–NaBH4 (3.3–3.6 nm) and Pt–H2O–NaBH4 (5.7–6.2 nm) catalysts. The Pt–EG-complex catalyst has the highest electrochemical surface area and shows the highest catalytic performance for methanol electro-oxidation.