info:eu-repo/semantics/article
Evolution of adsorbed CO on Pt and Pt/Au surface
Fecha
2018-04-20Registro en:
del Giudice, Gabriela Andrea; Tesio, Alvaro Yamil; Cappellari, Paula Sofía; Palacios, Rodrigo Emiliano; Planes, Gabriel Angel; Evolution of adsorbed CO on Pt and Pt/Au surface; Pergamon-Elsevier Science Ltd; Electrochimica Acta; 270; 20-4-2018; 48-53
0013-4686
CONICET Digital
CONICET
Autor
del Giudice, Gabriela Andrea
Tesio, Alvaro Yamil
Cappellari, Paula Sofía
Palacios, Rodrigo Emiliano
Planes, Gabriel Angel
Resumen
In this work, we studied in detail one of the possible limiting-steps during CO oxidation at Pt and Pt/Au electrodes, namely CO adsorption and diffusion at the electrode's surface. With this aim, we used an electroless method for Pt surface modification, which entails the spontaneous deposition of gold at Pt electrodes. We also use a home-made fast-response (four electrodes) flow cell that allows an accurate control of the electrode exposition time to CO (tad) and of the time interval (tw) before stripping of the adsorbed CO (COad). Thus two key experimental parameters of the electro-oxidation process can be independently modified and the results evaluated. Our results are consistent with a mechanism in which CO is initially adsorbed onto active sites and then moves away by surface diffusion. As a result, the subsequent oxidative stripping elimination of CO starts with COad far away from the most active sites. The experiments carried out for Pt/Au electrodes with different fraction of electrode area covered by CO (θCO) demonstrate that Au acts as a barrier, hindering the surface diffusion of CO from/to the active sites, giving raise to the multiple pecks observed when tw is low.