International Journal of Hydrogen Energy, Vol.42, No.14, 9202-9209, 2017
Pt-modified Au/C catalysts for direct glycerol electro-oxidation in an alkaline medium
Au-based catalysts promoted with Pt were prepared by using polyvinyl alcohol protection method. Different amounts of Pt (5, 10 and 15% of total metal) were added in the Au sol formation step to improve the activity of Au/C toward glycerol electro-oxidation in an alkaline medium. The physical and electrochemical properties of the as-prepared catalysts were explored. The average particle sizes of the Au/C and Pt-modified Au/C catalysts measured by transmission electron microscopy (TEM) were the same at around 4 nm. The PtAu/C alloy formation in the PtAu/C catalysts was confirmed by the increase of lattice parameter calculated from the X-ray diffraction (XRD) patterns and by the absence of Pt ring in the electron diffraction pattern. The change of binding energy in X-ray photoelectron spectroscopy (XPS) results indicated the interaction between Pt and Au. For glycerol electro-oxidation in an alkaline medium, the PtAu/C catalysts were more active than the Au/C catalyst as observed from an early onset potential and a shift of potential at maximum current density to a lower potential. Among the Pt-modified Au/C catalysts, the most active catalyst was PtiAug/C. The synergistic effects between Pt Au was proven by a better performance of the PtAu/C compared to the physical mixed catalyst of Au/C and Pt/C at the same Pt:Au ratio. The Pt-modified Au/C catalysts were more stable than the Au/C, especially in a high potential region. This enhancement may be caused by the promotion effect of highly active PtO on the surface of the bimetallic catalyst. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.