Effect of pH value on performance of PtRu/C catalyst prepared by microwave-assisted polyol process for methanol electrooxidation

PtRu/C catalysts with different mean particle sizes have been synthesised by microwave-assisted polyol process at various pH values and characterised by transmission electron microscopy (TEM), energy dispersive analysis of X-ray (EDAX) and X-ray diffraction (XRD). Their electrochemical performances have been tested by cyclic voltammetry, amperomeric i-t, and CO-stripping techniques. The effects of pH values on performances of the PtRu/C catalysts have been mainly investigated. It has been found that the particle size, composition and catalytic activity of the PtRu/C catalyst are very sensitive to the pH value of reducing solution, and the PtRu/C catalyst prepared at the pH value of 8 exhibits the better performance for methanol electrooxidation than the other samples. The size of the nanoparticles decreases as the pH value increases from 0.2 to 10 with the largest size of 4.4 nm and the smallest one of 2.1 nm. The two metal elements distribute uniformly in the catalyst and their metal loadings are similar to the theoretical value.