Electrochemical Behavior and Semiempirical Approach to the Electroadsorption of 3-Buten-2-one and 2-Butanone on Platinum

✍ Scribed by C.F Zinola; A.M Castro Luna

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 266 KB
• Volume: 219
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1999.6480

✦ Synopsis

The electroadsorption of 3-buten-2-one was studied on polycrystalline and faceted Pt electrodes in aqueous 0.5 M H 2 SO 4 between 20 and 70°C using voltammetric and transient techniques. The largest values of anodic charge densities in stripping experiments were observed at the potential of zero charge of the Pt/acid interface (ca. 0.20 V), that is, 550, 680, and 720 C cm ؊2 , on polycrystalline and (111)-and (100)-faceted electrodes, respectively. The anodic and cathodic strippings of 3-buten-2-one showed the formation of at least two residues with different electrochemical behavior. For comparison cyclic voltammetries and current transients of 2-butanone on Pt were also studied. To get a deeper insight into the adsorption configurations of 3-buten-2-one and 2-butanone, the extended Hu ¨ckel molecular orbital methodology was used to predict adsorption geometries and binding energies on simulated Pt(100) and Pt(111) single-crystal surfaces. At equilibrium potentials, two types of adsorbed species were recognized, a planar 3-buten-2-one formed by the interaction of carbonyl and alkene groups and adsorbates coming from the single interaction of the >CAO moiety for both 3-buten-2-one and 2-butanone. At simulated positive potentials, 3-buten-2-one adsorption occurred on Pt(111) and Pt(100) clusters through the -orbitals of the >CAC< moiety, whereas at negative potentials 3-buten-2-one was adsorbed via -bridging or di-configuration(s).