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O: Fachverband Oberflächenphysik

O 67: Solid-Liquid Interfaces III: OER, ORR, CO2RR, etc.

O 67.3: Vortrag

Mittwoch, 18. März 2020, 11:15–11:30, WIL C107

Ni-doped fe3o4(001) surface as simple model to understand oxygen evolution reaction — •Francesca Mirabella, Matthias Müllner, Florian Kraushofer, Michael Schmid, Gareth Parkinson, and Ulrike Diebold — Technische Universität Wien, Vienna, Austria

Electrochemical water splitting is an environmentally friendly technology to convert renewable energy into h2-fuels. Among the Earth-abundant first-row transition metal- based catalysts, mixed ni-fe oxides have shown promising performance for effective and low-cost catalysis of the oxygen evolution reaction (OER) in alkaline media. However, the synergistic role of fe and ni cations on the OER mechanism is yet unclear. The goal of this study is to develop a well-defined model system for understanding the OER and establishing the structure-reactivity relation on mixed fe/ni oxides. Reconstructed fe3o4(001) provides well-defined sites for the adsorption or incorporation of various metal atoms including ni. We combine UHV surface science techniques (LEED, XPS, ISS, STM) with exposure to ultrapure liquid water as well as cyclic voltammetry (CV) on UHV-prepared surfaces in alkaline media. When adding ni, we observed a significant improvement in the OER activity compared to the clean fe3o4 (001). An optimum fe:ni ratio of 1:9 is found, in good agreement with what was observed in powder catalysts. This observation makes our model system well suited to study the OER in alkaline media and gain further insight based on the high level of control of the surface and near-surface region, robustness and simplicity.