A comparative study of Pt/C and Pt–MoO x /C catalysts with various compositions for methanol electro-oxidation

Abstract: The methanol electro-oxidation behaviors on the Pt–MoO x /C catalysts with various compositions were investigated and compared to those of Pt/C catalyst by cyclic voltammetry and chronoamperometry. The Pt–MoO x /C catalysts were prepared by depositing Pt on the MoO x /C support obtained by precipitation-reduction method in advance. The physical properties of the prepared catalysts were characterized by XRD, XPS, EDX and TEM. From the results of XRD and TEM, it was shown that the MoO x /C support facilitated the dispersion of Pt particles. All the Pt–MoO x /C catalysts showed relative lower Mo contents comparing to their nominal values. No PtMo alloy was formed in these catalysts, which were affirmed by XPS and XRD. It was found that all the Pt–MoO x /C catalysts showed higher mass activity (normalized to the mass of Pt) but lower specific activity (normalized to the electrochemical active surface areas) for methanol oxidation than the Pt/C catalyst. With the increase of Mo contents in Pt–MoO x /C catalysts, the activities of Pt–MoO x /C catalysts decreased. Combined with the composition and structure analyses, the differences in methanol oxidation on these catalysts were attributed to the interaction between the Pt particles and the MoO x /C support. It was suggested that the Pt metal–MoO x /C support interaction resulted in two effects. One was decreasing the Pt particle size; the other was decreasing the specific activities of these catalysts for methanol oxidation. Comprising these two contradictory effects, the mass activities of these catalysts for methanol oxidation increased. [Copyright &y& Elsevier]