Synthesis, characterization and electrochemical studies of Ti-incorporated tungsten trioxides as platinum support for methanol oxidation

Platinum supported on high surface area tungsten trioxide (WO3) has received intensive attention in recent years, mainly because of its improved tolerance towards carbon monoxide (CO) poisoning during methanol oxidation and its enhanced electrocatalytic activity. However, the chemical instability Of WO3 in acid medium is a major issue that hinders its application in fuel cell electrodes. In the present work, the stability Of WO3 is shown to be improved by suitable Ti-4 substition in the WO3 framework. However, the improvement in the stability Of WO3 in acid medium was found to be significant only at lower amounts of Ti-4 in the framework. On the other hand, the electrocatalytic activity of Pt loaded W1-xTixO3/C (x=0.0, 0.05, 0.09 and 0.17) for methanol oxidation, evaluated by cyclic voltammetry, in acid medium follows the order: Pt-W0.83Ti0.17O3/C > Pt-WO3/C > Pt-W0.91Ti0.09O3/C similar to Pt-W0.95Ti0.05O3/C. The trend in the activity observed correlates well with that of the increase in the ohmic resistance of the electrode determined by electrochemical impedance spectroscopy. (c) 2004 Elsevier B.V. All rights reserved.