Alloy ratio effect of Pd/Pt nanoparticles on carbon nanotubes for catalysing methanol-tolerant oxygen reduction

Pd1Pt3, Pd1Pt1, and Pd3Pt1 nanoparticles supported on multi-wall carbon nanotubes (CNTs) were prepared by the self-regulation reduction of sodium n-dodecyl sulphate and used as catalysts in oxygen reduction reactions (ORRs). The crystal properties of these alloy nanoparticles on the CNT were measured by X-ray diffraction spectroscopy (XRD) and high-resolution transmission electron microscopy (HRTEM). The angle shifting of the XRD peak and the lattice spacing of the nanoparticles measured by HRTEM increased with an increase in Pd amount, indicating a regulable Pd–Pt ratio for the alloy nanoparticle composition. Rotating ring-disk electrode (RRDE) measurements indicate that the number of electrons catalysed by the Pd1Pt3/CNT, Pd1Pt1/CNT, and Pd3Pt1/CNT nanocatalysts in the ORRs were 3.98, 3.97, and 3.93, respectively. These results show that these ORRs occur via a 4-electron pathway. Linearly scanned voltammetry in the electrolyte with methanol revealed that Pd3Pt1/CNT has high methanol tolerance during ORRs.