Bi-metallic and tri-metallic Pt–Sn/C, Pt–Ir/C, Pt–Ir–Sn/C catalysts for electro-oxidation of ethanol in direct ethanol fuel cell

Abstract

In the present work, combination of bi-metallic and tri-metallic Pt, Ir, Sn electro-catalysts was prepared by impregnation reduction method on carbon Vulcan XC-72 to improve upon electro-oxidation of ethanol in direct ethanol fuel cell. The prepared electro-catalysts were characterized by means of scanning electron microscope (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) analyses. XRD and TEM analyses reveal that the prepared catalysts are of nano size (6–10nm) range. It is shown that Pt lattice parameter decreases with the addition of Ir, and increases with the addition of Sn in Pt–Ir–Sn/C catalyst. The electro-catalytic activities characterized by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry (CA) techniques reveal that the addition of small amount of Ir in Pt–Sn/C electro-catalyst exhibits higher activity towards ethanol oxidation than the Pt–Sn/C (20% Pt and 20% Sn by wt) electro-catalyst. The single direct ethanol fuel cell (DEFC) test at 90°C, 1bar with catalyst loading of 1mg/cm2 and 2M ethanol as anode feed showed an enhancement of catalytic activity in following order: Pt–Ir–Sn/C (20% Pt, 5% Ir and 15% Sn by wt)>Pt–Ir–Sn/C (20% Pt, 10% Ir and 10% Sn by wt)>Pt–Sn/C (20% Pt and 20% Sn by wt)>Pt–Ir–Sn/C (10% Pt, 15% Ir and 15% Sn by wt)>Pt–Ir/C (20% Pt and 20% Ir by wt)> Pt/C (40% Pt by wt). Pt–Ir–Sn/C (20% Pt, 5% Ir and 15% Sn by wt) exhibited highest performance among all the catalysts prepared with power density of 29mW/cm2 in DEFC operating at 90°C.