Abnormal infrared effects and electrocatalytic properties of nanometer scale thin film of PtRu alloys for CO adsorption and oxidation

摘要

Nanometer scale thin films of PtRu alloy supported on glassy carbon (nm-PtRu/GC) were prepared using electrochemical codeposition under cyclic voltammetric conditions. The composition of the PtRu alloy was altered by varying the concentration of Pt4+ and Ru3+ ions in the deposition solution. STM results demonstrated that the nm-PtRu film was composed of crystallites appearing in a layered hexagonal form. The nm-PtRu/GC exhibited a high catalytic activity for CO oxidation, consisting mainly in a negative shift of potential for COad oxidation. In situ FTIR spectroscopic studies revealed that the nm-PtRu/GC alloy electrodes of different surface composition exhibit abnormal infrared effects (AIREs) as observed on electrodes of nanometer scale thin films of transition metals. The AIREs observed on nm-PtRu/GC electrodes consist in the inversion of COad bands, the significant enhancement of IR absorption and an increase in the FWHM. Following the increase in Ru component in the nm-PtRu thin film the FWHM was increased progressively from 20 cm(-1) on a nm-Pt/GC to 55 cm(-1) on a nm-Ru/GC electrode, and the enhancement factor of IR absorption by COL was between 10.5 to 13.1. The present study has provided new understanding of the structure and properties of nanometer scale thin film PtRu alloy material, and highlights its potential for fuel cell applications. [References: 39]