Electrosorption of hydrogen into palladium-gold alloys |
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Authors: | M. Łukaszewski K. Kuśmierczyk J. Kotowski H. Siwek A. Czerwiński |
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Affiliation: | (1) Department of Chemistry, Warsaw University, Pasteura 1, 02-093 Warsaw, Poland,;(2) Industrial Chemistry Research Institute, Rydygiera 8, 01-793 Warsaw, Poland, |
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Abstract: | Hydrogen electrosorption into Pd-Au alloys has been studied in acidic solutions (1 M H2SO4) using cyclic voltammetry. Pd-Au electrodes with limited volume were prepared by electrochemical co-deposition. It was found that the maximum H/(Pd+Au) ratios decrease monotonically with increasing gold content and reach zero at ca. 70 at% Au. Similarly to the case of Pd limited volume electrodes, two peaks in the hydrogen region, corresponding to two types of sorbed hydrogen, are observed on voltammograms for Pd-rich alloys. The hydrogen capacity, H/(Pd+Au), measured electrochemically, depends on the sweep rate in the cyclic voltammetry experiments, which suggests that two different mechanisms for hydrogen desorption from the Pd-Au alloy are possible. After a strong decrease of Pd concentration at the electrode surface, caused by long cyclic polarization to sufficiently anodic potentials, the amount of absorbed hydrogen is still significant for alloys initially rich in Pd. The results obtained from CO adsorption experiments suggest that only Pd atoms are active in the hydrogen absorption/desorption process. Electronic Publication |
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Keywords: | Palladium-gold alloys Hydrogen sorption Carbon monoxide adsorption Limited volume electrodes |
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