Synthesis of well-dispersed PtRuSnOx by ultrasonic-assisted chemical reduction and its property for methanol electrooxidation

PtRuSnOx supported on multi-wall carbon nanotubes (MWCNTs) was prepared by ultrasonic-assisted chemical reduction method. The as-prepared catalyst was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD patterns indicate that Pt exists as the face-centered cubic structure, Ru is alloyed with platinum, while non-noble metal oxide SnOx exists as an amorphous state. From TEM observation, PtRuSnOx is well dispersed on the surface of MWCNTs with the particle size of several nanometers. The electrochemical properties of the as-prepared catalyst for methanol electrooxidation were studied by cyclic voltammetry (CV) and chronoamperometry (CA). The onset potential of methanol oxidation on PtRuSnOx and PtRu catalysts is much more negative than that on Pt catalyst, shifting negatively by about 0.20 V, while the peak current density of methanol oxidation on PtRuSnOx is higher than that on PtRu. Electrochemical impedance spectroscopy (EIS) studies also show that the reaction kinetics of methanol oxidation is improved with the presence of SnOx. The addition of non-noble metal oxide SnOx to PtRu promotes the catalytic activity for methanol electrooxidation and the possible reaction mechanism is proposed.