engleski

Pt-Based Bimetallic Electrocatalysts for Application in Fuel Cells: Electrooxidation of Carbon Monoxide

In methanol fuel cell technology the poisoning of the catalyst surface with adsorbed CO as the intermediate reaction product, represents a serious technological and ecological problem. In recent times a number of attempts have been made to find a suitable catalysts for CO oxidation, as well as in improving thc catalytic activity of platinum by modification of its surface with the addition of the second metal - bimetallic catalysts. We performed the investigations of CO electrooxidation on platinum electrode modifed with Ru, Sn, and Bi. The catalysts were produced by the potential-controlled deposition (PCD), as well as the under-potential deposition (UPD) of the electroactive components on the inert conductive substrate (Au-substrate). This procedure yielded the highly-dispresed catalyst surface area with a controlled roughness. Thc investigations were performed in perchloric acid using stripping voltammetry, chronoamperometry, chronopotentiometry and electrochemical impedance spectroscopy (EIS) techniques. An EG&G PAR Model 273 potentiostat and an EG&G PAR Lock-in Amplifier, Model 5301A, controlled.by PC, were used in all measurements. Impedance measurements were performed in the frequency range from 50 kHz to 40 mHz, with the ac voltage amplitude of ą 5 mV. Analysis of the results showed that the kinetic and mechanism of the CO oxidation reaction depended on the relative fraction of the catalyst componenets. The best results, in view of the energy efficiency and surface stability, showed Pt-Ru catalyst. No difference in the catalytic activity between UPD and electrodeposited catalysts were noticed.

fuel-cell; electrocatalysys; underpotential deposition; adsorption; carbon monoxide; bifunctional mechanism; bifunctional catalysts; platinum; ruthenium; busmuth; tin; impedance spectroscopy; stripping voltammetry

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