Synthesis of Carbon-Supported Pt–YOx and PtY Nanoparticles with High Catalytic Activity for the Oxygen Reduction Reaction Using a Microwave-based Polyol Method

Carbon-supported PtY alloy nanoparticles were prepared as oxygen-reduction reaction (ORR) catalysts by reducing a mixture of cis-[Pt(NH3)2(NO2)2] or Pt(C5H7O2)2 and Y(CH3COO)3·4H2O in ethylene glycol (EG) with microwave (MW) heating. Microstructure and composition analyses of products using TEM, TEM-EDS, XRD, XPS, and ICP-AES data showed that Pt-YOx/C (Y/Pt = 0.110.75) catalysts involving amorphous yttrium oxide were formed as major products. When the YOx component in catalysts was removed using HNO3 treatment, Pt99.1-99.6Y0.4-0.9/C alloy catalysts with low Y contents remained. Higher ORR activity was shown by Pt-YOx/C and PtY/C catalysts than by Pt-Y(OH)3/C, Pt-YOx/C, or PtY/C catalysts prepared using other conventional chemical reduction methods and thermal treatment methods under a H2/Ar or Ar atmosphere. The mass activity (MA) and surface specific activity (SA) of the best Pt99.5Y0.5/C catalyst, MA = 245 A g-1 Pt and SA =711 A cm-2 Pt, were equal to or higher than those of commercially used Pt86Co14/C catalyst, MA = 245 A g-1 Pt and SA = 512 A cm-2 Pt. Major reasons for the high ORR activity of these Pt-YOx/C and PtY catalysts are discussed. These Pt99.1-99.6Y0.4-0.9/C alloy catalysts prepared using acid treatment are new and promising catalysts for use in proton exchange membrane fuel cells (PEMFCs).