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⋅4 H2O in ethylene glycol (EG) with microwave (MW) heating. Microstructure and composition analyses of products by using TEM, TEM–energy-dispersive X-ray spectroscopy (EDS), XRD, X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma atomic emission spectroscopy (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 the catalysts was removed by 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 by 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 gPt −1 and SA=711 μA cmPt −2, were equal to or higher than those of the commercially used Pt86Co14/C catalyst, MA=245 A gPt −1 and SA=512 μA cmPt −2. The 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 by using acid treatment are new and promising catalysts for use in proton exchange membrane fuel cells (PEMFCs).
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