Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 93: Heterogeneous Catalysis: Experiment

O 93.3: Vortrag

Donnerstag, 23. März 2017, 16:00–16:15, TRE Phy

In operando study on MnOx thin films during electro-catalytic water oxidation using soft x-ray absorption and emission spectroscopy — •Maryam N. Shaker1,2, Marc F. Tesch1, Shannon A. Bonke3, Alexandr Simonov3, Leone Spiccia3, and Emad F. Aziz1,21Helmholtz Zentrum Berlin — 2Freie Universität Berlin — 3School of Chemistry, Monash University, Clayton, VIC, 3800, Australia

Manganese oxides (MnOx) are promising candidates to act as catalysts for the water oxidation half reaction, which is mandatory to produce hydrogen from water. To systematically understand what drives the catalytic efficiency of MnOx a comprehensive knowledge about its electronic structure is necessary. A powerful tool to study the electronic structure of transitions metal oxides is soft X-ray spectroscopy. However, such studies are usually restricted to ex situ measurements unable to unambiguously identify structural and electronic changes of the material occurring at working conditions, i.e. applying a potential. Here, we present an in operando study using X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) at the Mn L-edge of electrodeposited MnOx films while applying potentials in a systematic fashion. Clear, potential dependent spectral changes related to variations in the Mn oxidation state were observed. The XAS spectra taken in operando are compared to ex situ XAS measurements and will be discussed with respect to in operando RIXS measurements revealing distinct changes in the structure of the occupied valence state, which play a key role for all catalytic reactions.

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