Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 92: Gerhard Ertl Young Investigator Award

O 92.3: Vortrag

Donnerstag, 23. März 2017, 11:30–12:00, TRE Ma

Tuning the electrocatalytically active site: atomic ensemble effects and surface strain — •Maria Escudero-Escribano — Technical University of Denmark, Department of Physics, Fysikvej, 2800 Kgs. Lyngby (Denmark)

In order to improve the kinetics of the oxygen reduction reaction (ORR), we can modify the geometric structure (1) and/or alter the electronic properties of the surface atoms (2,3) of the catalyst.

We used a self-ordered molecular pattern, cyanide-modified Pt(111), to study the ORR (1) and to decorate surfaces at the atomic scale (4,5). My electrochemical scanning tunneling microscopy images provided an atomically resolved visualization of the honeycomb structure in the presence of cations (4). Interestingly, CN groups block the adsorption of spectator anions in the electrolyte, while allowing the adsorption of oxygen. As a consequence, CN-Pt(111) presents a 25-fold enhancement over Pt(111) (1).

In addition, we have studied novel Pt-lanthanide alloys for ORR. A Pt overlayer is formed onto the bulk alloys by acid leaching. Our surface-sensitive X-ray diffraction measurements on Gd/Pt(111) show the formation of a crystalline Pt overlayer under compressive strain (6). The ORR activity versus the lattice parameter follows a volcano relation (2). We use the lanthanide contraction to control surface strain effects and tailor the activity, stability and reactivity of Pt.

(1) Nature Chem. 2010, 2, 880; (2) Science 2016, 352, 73; (3) J. Am. Chem. Soc. 2012, 130, 16476; (4) ChemPhysChem 2011, 12, 2230; (5) J. Phys. Chem. C 2009, 113, 12340; (6) Nano Energy 2016.

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