Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 30: Surface Chemical Reactions and Heterogeneous Catalysis II
O 30.6: Vortrag
Dienstag, 1. April 2014, 11:45–12:00, PHY C 213
Ligand-controlled electrocatalytical response in the oxygen reduction reaction in iron-based 2D metal-organic structures — Doris Grumelli1, •Benjamin Wurster1, Sebastian Stepanow1, Rico Gutzler1, and Klaus Kern1,2 — 1Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany — 2Institut de Physique de la Matière Condensée, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
In this work we present the electrochemical characterization of single iron atoms coordinated by either tetracyanoquinodimethane (TCNQ), bis-pyridyl-bipyrimidine (PBP) or phythalocyanine (Pc) on Au(111).
The samples were prepared under ultra-high vacuum (UHV) conditions by evaporating either FePc or the organic ligands together with iron, which subsequently self-assemble and form two-dimensional metal-organic coordination networks. By scanning tunneling microscopy in UHV the composition and structure of the networks and FePc layer were controlled and characterized. The sample is brought from UHV to the electrochemical cell through a transfer chamber in a controlled environment, in which the catalytic activity towards the oxygen reduction reaction in alkaline media is studied. Linear voltammetry experiments show that depending on the coordination environment of Fe the mechanism of the reduction of O2 is changed. TCNQ-Fe catalyzes the reduction towards H2O2 on a 2e− pathway. For PBP-Fe and FePc the complete reduction to H2O is observed. PBP-Fe catalyzes on a (2+2)e− pathway, while FePc on a direct 4e− pathway.