Temperature dependence on methanol oxidation and product formation on Pt and Pd modified Pt electrodes in alkaline medium

摘要

The effect of temperature on the catalytic oxidation of methanol on electrodeposited platinum and platinum-palladium alloy were carried out for a temperature range of 293-353 K. The morphology of the catalyst surface was studied using scanning electron microscopy, where as the structure and bulk composition of the Pt-Pd/C catalyst were determined by X-ray diffraction and energy dispersive X-ray spectroscopy. Cyclic vol-tammetry, chronoamperometry and electrochemical impedance spectroscopy were used to investigate the electrochemical parameters related to electro-oxidation of methanol under the influence of temperature. Apparent activation energies of the oxidation reactions on Pt/C and Pt-Pd/C were determined at different potentials within the same temperature range. A pronounced influence of temperature towards methanol oxidation was observed on the Pt-Pd/C catalyst as compared to Pt alone. The incorporation of Pd into Pt decreases the charge transfer resistance and activation energy of the methanol oxidation substantially which ensures greater tolerance of this catalyst towards methanolic residues. Quantitative analysis of the oxidation reaction product by ion chromatography further substantiates the much better performance of the Pt-Pd electrode than Pt alone for electrocatalytic oxidation of methanol in alkaline medium.