PtRu nanoparticles supported on the carbon, with different mean particle sizes, were synthesized by microwave-assisted ethylene glycol process, the effects of pH on the PtRu/C catalyst were mainly investigated. UV-Vis spectroscopy, energy dispersive X-ray analysis, transmission electron microscopy, and X-ray diffraction were applied to characterize the PtRu nanoparticles. The solution pH had important influence on the metal particle size. TEM results indicated that the PtRu mean particle size decreased from 3.5 nm to 1.5 nm with the increase of pH value. However, when pH value reached 11.0, the metal loading of synthesized catalyst decreased distinctly because the metal nanoparticles were protected in solution. The results showed that the PtRu/C catalyst synthesized at pH ca 9.0, with appropriate particle sizes (2.4 nm) and homogenous dispersed particles, had the highest electrocatalytic activity for methanol electrooxidation among all the synthesized catalysts
