Electrochemical and morphologic studies of nickel incorporation on graphite electrodes modified with polytyramine |
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Authors: | Cláudio M de Castro Sabrina N Vieira Rafael A Gonçalves Ana G Brito-Madurro João M Madurro |
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Affiliation: | 1. Institute of Chemistry, Federal University of Uberlandia, Av. Jo?o Naves de ávila, 2121, Caixa Postal 593, Uberlandia, MG, 38400-902, Brazil 2. School of Mechanical Engineering, Federal University of Uberlandia, Uberlandia, 38400-902, Brazil
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Abstract: | Electrodes modified with electropolymerized films have received considerable attention in the development of catalysts and
sensors, and their use is rapidly increasing. This work reports modification of the surface of graphite electrodes by electrochemical
polymerization of tyramine. These modified electrodes were used to nickel incorporation and hydrogen evolution. Tyramine electrooxidation,
in acid and basic media, yielded polymeric films onto graphite surface. In ferrocyanide/ferricyanide solution, the electrodes
modified in acid medium showed higher electron transfer efficiency. Impedance studies indicated higher charge transfer resistance
to electrodes modified with Ptyr prepared in basic pH. Scanning electron microscopy showed that the formed films present different
morphology for the several pH values studied. Interferometry and scanning electron microscopy analysis showed higher coverage
to films formed in acid medium. Polymers produced in more alkaline medium present growth self-limited. Nickel was incorporated
in the films through immersion of the modified electrodes in solution of potassium hexafluoronickelate, followed of electrochemical
reduction of the metal. The electrocatalytic activity of the modified electrodes with nickel incorporated was tested for hydrogen
evolution reaction. The amount of nickel mass incorporated as well as the current density of hydrogen evolution reaction was
higher in electrodes modified with polytyramine produced in acid medium. |
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