title: The electrochemical promotion of ethylene oxidation at a Pt/YSZ catalyst.
abstract: The electrochemical promotion of the C(2)H(4)+O(2) reaction to form CO(2) and H(2)O is studied in the 10(-5) and 10(-4) mbar range with a Pt catalyst interfaced as working electrode to yttrium-stabilized zirconia (YSZ). Photoemission electron microscopy (PEEM) was used as spatially resolving method. Under open-circuit conditions, that is, without an external voltage applied, the CO(2) production exhibits a pronounced hysteresis upon cyclic variation of p(C(2)H(4)). The hysteresis is attributed to the build-up of a carbonaceous CH(x) layer inhibiting O(2) adsorption and hence poisoning the reaction. It is shown that the application of a positive potential of 1 V triggers a transition from the unreactive branch of the reaction to an active branch. The large non-Faradayicity reported in the literature for this reaction system is explained as an ignition effect caused by the partial removal of the inhibiting carbonaceaous layer.
authors.affiliation: Institut für Physikalische Chemie und Elektrochemie, Leibniz-Universität Hannover, Callinstrasse 3-3a, 30167 Hannover, Germany.
authors.forename: Arafat
authors.initials: A
authors.lastname: Toghan
authors.forename: Liz M
authors.initials: LM
authors.lastname: Rösken
authors.forename: Ronald
authors.initials: R
authors.lastname: Imbihl
mesh_terms: D002245:Carbon Dioxide / Q000138:chemical synthesis / Q000737:chemistry; D002384:Catalysis; D004563:Electrochemistry; D005030:Ethylenes / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D010984:Platinum / Q000737:chemistry*; D013499:Surface Properties; D014867:Water / Q000737:chemistry; D015019:Yttrium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D005030:Ethylenes; D014867:Water; D002245:Carbon Dioxide; D010984:Platinum; D015019:Yttrium; C036216:ethylene; D015040:Zirconium; C028541:zirconium oxide; D010100:Oxygen