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Abstract: Fe phthalocyanine (FePc) and Co porphyrin (CoPh) modified reduced graphene oxide (rGO) nanosheets were used as non-noble metal electrocatalysts for oxygen reduction reaction (ORR). The surface morphology, graphitisation and surface composition of the catalyst materials were characterised by scanning electron microscopy, micro-Raman spectroscopy and X-ray photoelectron spectroscopy. Electrochemical experiments with FePc/rGO and CoPh/rGO catalysts were carried out in 0.1M KOH employing the rotating disc electrode (RDE) method. The RDE results show that both MN4-macrocycle/rGO modified glassy carbon electrodes are highly active for ORR in alkaline solution. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]