A Study of of CO Adsorption/Desorption on a Thin Platinum Film by the Measurement of Electrical Resistance

Abstract

© 2018 The Electrochemical Society. Carbon monoxide (CO) poisoning of platinum catalysts in proton exchange membrane fuel cells (PEMFC) substantially affects cell performance. Many studies have been reported on performance degradation even with very small concentrations of CO in hydrogen. The present work investigated carbon monoxide adsorption/desorption in situ on a 1 nm thick platinum film deposited on a sapphire substrate by measuring electrical resistance of the film as a function of CO concentration, exposure time and testing temperature. The experimental data showed an increase in film resistance upon exposure to CO containing gases. The film resistance was sensitive to CO exposure at a concentration as low as 1 ppm. A model was developed to determine rate constants and activation energies for CO adsorption/desorption on Pt surface using the measurement of electrical resistance as a function of time.