Studies on how to obtain the best catalytic activity of Pt/C catalyst by three reduction routes for methanol electro-oxidation

Carbon-supported platinum (Pt/C) catalysts were prepared via reduction in three different routes: Sodium borohydride (NaBH4), ethylene glycol (EG), and EG with NaBH4 (EG-NaBH4). The reduction conditions of each procedure were systematically optimized to achieve maximum Pt/C catalytic activity for methanol electro-oxidation as determined via cyclic voltammetry (CV). The EG-NaBH4 process showed greater activity for methanol oxidation than those prepared by the NaBH4 and EG processes and the Johnson Matthey 40 wt% Pt/C catalyst with the support of carbon black (Pt-JM). The average size of the particles for each of the three preparation processes determined from the XRD data was 4.8, 4.1, and 2.5 nm, respectively. The average surface area of the catalyst particles was determined to be 58, 68, and 112 m(2).g(Pt)(-1), respectively. Analysis by X-ray diffraction (XRD), transmission electron microscopy (TEM), and CV suggest that the greater activity for methanol oxidation of the Pt/C catalyst prepared by the EG-NaBH4 process is due to the smaller particle size, better cluster dispersion, and an increase in the number of Pt(110) surface sites achieved using this method. (C) 2011 Elsevier B.V. All rights reserved.