Pt/C catalysts with narrow size distribution prepared by colloidal-precipitation method for methanol electrooxidation

A simple, environment-friendly and aqueous-route colloidal-precipitation method is successfully employed to prepare carbon supported platinum nanoparticles with a narrow size distribution. In this method, (NH4)2WO4 is used to react with H2PtCl6, which forms the (NH4)2PtCl6 and H2WO4 simultaneously. The precipitation of (NH4)2PtCl6 and the colloidal of H2WO4 can protect the formation of the Pt nanoparticles. Transmission electron microscopy demonstrates that the Pt nanoparticles with a narrow size distribution are well dispersed on the carbon support. More importantly, the size of the Pt nanoparticles can be simply controlled by tuning the concentration of (NH4)2WO4 and the Pt nanoparticles prepared in the 0.5 mmol L−1 (NH4)2WO4 exhibit the smallest size of ca. 3 nm. Further, cyclic voltammetric and chronoamperometric experiments show that the prepared Pt/C catalyst exhibited excellent catalytic activity and stability compared with the Pt/C prepared by impregnation method and the state-of-the-art commercial Pt/C. For example, the peak current and the stable current at 3600 s of the Pt/C catalyst prepared with the 0.5 mmol L−1 (NH4)2WO4 is about 1.24 and 1.78 times of the commercial Pt/C. Therefore, the as-proposed colloidal-precipitation method exhibits a potential application in preparing highly dispersive and electroactive Pt/C catalysts for direct methanol fuel cells.

► Colloidal-precipitation method was explored to prepare Pt/C.
► The prepared Pt nanoparticles dispersed well and had a narrow size distribution.
► Particle size of the Pt can be well controlled.
► The Pt/C showed enhanced activity and stability for methanol electrooxidation.