Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 13: Solid-Liquid Interfaces I: Electrocatalysis and Photoelectrochemistry

O 13.2: Vortrag

Montag, 1. April 2019, 15:15–15:30, H16

In operando surface X-ray diffraction studies of Co oxide catalysts films for electrochemical water splitting — •canrong qiu, finn reikowski, olaf magnussen, and jochim stettner — Christian-Albrechts-Universität zu Kiel, Institut für Experimentelle und Angewandte Physik, Leibnizstraße 19, 24118 Kiel

Transition metal oxide have been receiving much recent interest as active and stable electrocatalysts for the anodic oxygen evolution reaction (OER). We present operando surface X-ray diffraction studies of two structurally well-defined epitaxial Co3O4(111) and CoOOH(001) films electrodeposited on Au(111). The potential-dependent structural changes were monitored with high time resolution up to OER current densities as high as 150 mA cm 2. The CoOOH(001) film is found to be smooth and perfectly stable over a wide potential range. In the case of Co3O4(111), fast and fully reversible structural changes are observed. The surface region of Co3O4(111) starts restructuring at potentials 300 mV negative of the onset of the OER, indicating that the process is related to the thermodynamically predicted Co3O4 /CoOOH(001) transition. The formed skin layer changes linearly with applied potential. The results are at variance with previous suggestions that di-*-oxo bridged Co cations are exclusively responsible for the OER activity of Co oxides.