抄録
Methanol oxidation is the anodic reaction in a direct methanol fuel cell (DMFC). The development of a new catalyst, which can efficiently promote the anode reaction, is very important. In this study, a Pt thin film and two kinds of Pt oxide thin films prepared by reactive sputtering were characterized by XRD, XPS and EPMA, then their methanol oxidation activities were investigated using the rotating disk electrode method in a (H2SO4+CH3OH) solution. The Pt, PtO and PtO2 thin films were obtained by sputtering a Pt target in 100% Ar, Ar - 50% O2 and 100% O2 plasma, respectively. Neither PtO nor PtO2 had an excellent activity when the thin films were used as-received. However, an apparent catalytic activity of methanol oxidation was observed in the partially reduced Pt oxide thin films, whose ratios of O/Pt were significantly decreased by passing a cathodic current. On the other hand, the methanol oxidation activity of the Pt thin film was hardly changed by the electrochemical reduction. The methanol oxidation current showed that the electrocatalytic activity of the partially reduced Pt oxide thin films was about hundred times higher than that of the Pt thin film. Therefore, the partially reduced Pt oxide is a material with a significant potential for use as a catalyst for not only the DMFC, but also a fuel cell using the carbon compound as the fuel.
