Hydrogen sorption in Pd monolayers in alkaline solution |
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Authors: | M.H. Martin |
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Affiliation: | Département de chimie, Université de Sherbrooke, 2500 blvd. de l’Universite, Sherbrooke, Québec, Canada, J1K 2R1 |
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Abstract: | Hydrogen adsorption/absorption at palladium monolayers (ML) deposited on monocrystalline Au(1 1 1) electrode was studied in 0.1 M NaOH solution. H charge isotherms demonstrated that adsorption started at potentials more positive than at thicker nanometric Pd/Au(polycrystal) deposits. Due to 3-dimensional deposit growth, absorption could be seen at all deposits thicker than 1 ML. Besides, H sorption at Pd/Au(1 1 1) monolayers was more reversible than at nanometric Pd/Au(polycrystal) deposits. Strong geometric and electronic effects due to the Au substrate were observed up to 5 Pd ML. Influence of benzotriazole (BTA) on H sorption was also investigated. BTA blocked H adsorption above 250 mV vs. RHE. At less positive potentials adsorbed BTA layer seemed to undergo a reorientation allowing H adsorption. Stationary and dynamic electrochemical impedance spectroscopy was used to obtain double layer capacitance and charge transfer resistance. BTA also promoted kinetically H sorption into Pd/Au(1 1 1) monolayer and Pd/Au(polycrystal) nanometric deposits. |
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Keywords: | Hydrogen adsorption and absorption Palladium monolayers Alkaline solutions Benzotriazole Isotherms Impedance spectroscopy |
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