Study of Methanol-tolerant Oxygen Reduction Reaction at Pt-Bi/C Bimetallic Nanostructured Catalysts

The nanostructured platinum-bismuth catalysts supported on carbon (Pt3Bi/C, PtBi/C and PtBi3/C) were synthesised by reducing the aqueous metal ions using sodium borohydride (NaBH4) in presence of a microemulsion. The amount of metal loading on carbon support was found to be 10 wt.-%. The catalyst materials were characterised by X-ray diffraction (XRD), X-ray fluorescence (XRF), transmission electron microscope (TEM) and electroanalytical techniques. The Pt3Bi/C, PtBi/C and PtBi3/C catalysts showed higher methanol tolerance, catalytic activity for oxygen reduction reaction (ORR) than Pt/C of same metal loading. The electrochemical stability of these nano-sized catalyst materials for methanol tolerance was investigated by repetitive cycling in the potential range of -250 to 150 mV(MSE). Bi presents an interesting system to have a control over the activity of the surface for MOR and ORR. All Pt-Bi/C catalysts exhibited higher mass activities for oxygen reduction (1-1.5 times) than Pt/C. It was found that PtBi/C catalyst exhibits better methanol-tolerance than the other catalysts.