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Aryl layers on glassy carbon and gold electrodes were degraded by hydroxyl radicals from UV photolysis of hydrogen peroxide. The electrode surfaces were modified via electrochemical reduction of two structurally different azobenzene diazonium derivatives. The degradation of the aryl films was studied by AFM, XPS and electrochemical measurements using [Fe(CN)6]4− as solution probe. While the prepared aryl layers inhibited the electrochemical response of hexacyanoferrate, their degradation with OH· radicals resulted in different electrochemical behaviours for glassy carbon and Au electrodes. The aryl layer on glassy carbon was thinned, indicated by the increasing reversibility of the [Fe(CN)6]4− response, whereas the aryl film on Au showed pinhole formation, indicated by the microelectrode behaviour of the hexacyanoferrate response without retarded reversibility. Keywords: Diazonium salts, Azobenzene derivatives, Hydroxyl radicals, Hexacyanoferrate |
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