New Electrocatalysts Prepared by Co-Sputter Deposition for the Direct Oxidation of Methanol

Abstract

Direct methanol oxidation catalysts Pt1-x-Tax (0<x<1) were prepared using co-sputter deposition. Characterization of these thin film catalysts was performed using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray Diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Assessment of the methanol oxidation activity of Pt1-x-Tax catalysts were achieved through half-cell experiments. Among all the Pt1-x-Tax catalysts, Pt0.77-Ta0.23 catalyst showed the best electrochemical area specific activity which was comparable to platinum-ruthenium alloy on carbon (PtRu/C) catalysts. Pt1-x-Tax catalysts worked as bi-functional methanol oxidation catalysts. The surface oxides species activated water molecules and hence facilitated the process of removing carbon monoxide from the platinum sites. The membrane electrode assembly (MEA) of Pt0.77-Ta0.23 catalyst was tested at 60, 80 and 90 °C. The power density achieved at 90 °C was 82 mW/cm2/mg Pt, which was 1.82 times of PtRu/C catalyst with similar platinum loading.