Microwave polyol synthesis of Pt/CNTs catalysts: Effects of pH on particle size and electrocatalytic activity for methanol electrooxidization

Pt nanoparticles with different mean sizes supported on carbon nanotubes were synthesized by microwave heating ethylene glycol solutions of platinum salt with different pH in present of CNTs as supports. TEM examinations showed that Pt particles become smaller and more uniform when the synthesis pH increased from 3.4 to 9.2. The mean particle size was 5.8, 5.2, 3.4 and 2.7 nm when the synthesis pH was 3.6, 5.8, 7.4 and 9.2, respectively. The effects of the pH on Pt particle size and distribution were investigated. The pH was an important factor that influenced the particle size. Pt particles size could be thus selected by adjusting the synthesis solution pH. Pt/CNTs with suitable and uniform Pt particle size could be obtained. Electrochemical measurements showed that the Pt/CNTs catalyst prepared from the synthesis solution pH of 7.4 exhibited better performances for methanol electrooxidization than other samples.