Estudo Comparativo da Reação de Eletrooxidação de Etanol sobre Superfícies de Rh e Rh-Au

The catalytic dissociation of small organic molecules on electrode surfacesis a topic of relevant interest in electrochemistry.1 The great challenge in ethanoloxidation is the cleavage of the C–C bond, which one of the path is via oxidation ofadsorbed ethanol to form acetaldehyde and acetic acid. This path is not so interesting,once only two and four electrons are released in this process, respectively.2 Thepresent work goals to get insight into the role of Au adatoms onto Rh polycrystallinesurface in the ethanol electrooxidation reaction. The Rh poly surface was characterizedelectrochemically in H2SO4 and NaOH (0,1 M) (Fig. 1). After surface characterizationthe ethanol electrooxidation was carried out and acid and basic media (Fig. 1).According to voltammetric profile is possible to note a small increase of electroactivitywhen the electrode is swept in basic media, evidencing the OH- contribution to oxidizethe ethanol molecule at low potential. he Figure 1 C shows the behavior of Rh electrode modified by Au (10-4 M) depositionand its application for EOR. The Au deposition was carried out taking account theupper potential (1.3 and 1.5 V) and cycles of deposition in order to observe theinfluence of Au oxidation state over the ethanol oxidation. According to CV two peaks at0.7 and 1.0 V rise, as a contribution of Au atoms favoring the ethanol oxidation. As theamount of Au increases onto Rh surface the first peak is more pronounced with respectto the second one, indicating that a synergistic effect between Rh-Au contributespositively to formation of intermediates species not observed on Rh.