Preparation of Pt/C Nanocatalysts by Ethylene Glycol Method in Weakly Acidic Solutions

Pt/C catalysts were prepared by ethylene glycol (EG) method in weakly acidic solutions adjusted by sodium citrate (Na₃Cit), sodium acetate (NaAc) and sodium hydroxide (NaOH), separately. The effects of alkalizing agent, pH and temperature were investigated by transmission electron microscopy (TEM) and CV. The composition and structure of Pt/C catalyst prepared at optimal conditions of 140°C and pH=6.7 adjusted by Na₃Cit was further characterized by X-ray photoelectron microscopy (XPS) and X-ray diffraction (XRD), respectively. The average particle size of Pt/C catalyst prepared using Na₃Cit is 2.1 nm, smaller than that of Pt/C catalyst (2.9 nm) prepared using NaAc, much smaller than that of Pt/C catalyst (100 nm) prepared using NaOH. The electrocatalytic activity of Pt/C catalysts prepared using Na₃Cit and NaAc for ethanol oxidation are 456.6 and 419.2 mA/mgPt, comparative to those of Pt/C catalyst prepared by typical EG method and commercial E- TEK Pt/C catalyst. Finally, the size control mechanism of Pt nanoparticles was discussed.