CO oxidation on non-alloyed Pt and Ru electrocatalysts prepared by the polygonal barrel-sputtering method

The CO oxidation on non-alloyed Pt and Ru electrocatalysts prepared by the polygonal barrel-sputtering method was investigated. Samples were prepared by sputtering Pt and Ru separately at room temperature. From the X-ray diffraction (XRD) measurement of the sample prepared on a SiO₂ glass plate, it was found that the sputtered metals are non-alloyed. Subsequently, the non-alloyed Pt and Ru electrocatalysts were prepared by the polygonal barrel-sputtering method using carbon powder as a support. The XRD patterns of these samples showed a single and very broad peak supporting the hypothesis of the non-alloyed Pt and Ru. No separate Ru reflections were visible, which could be attributed to Ru particle sizes smaller than 4 nm, as obtained by transmission electron microscopy (TEM). CO oxidation on the non-alloyed Pt and Ru electrocatalysts were evaluated by CO stripping voltammetry. This measurement revealed that the lower peak potential of CO oxidation varies, depending on the Pt content and the sputtering order. In addition, it was assumed that the CO oxidation reaction site for non-alloyed Pt and Ru electrocatalyst has a limited area including direct contact sites between the Pt and Ru particles.