Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 16: Heterogeneous Catalysis: Theory
O 16.9: Vortrag
Montag, 12. März 2018, 17:15–17:30, MA 141
Water splitting reaction on polar Lithium Niobate surfaces — •Christof Dues1, Wolf Gero Schmidt2, and Simone Sanna1 — 1Institut für Theoretische Physik, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 16, D-35392 Gießen — 2Department Physik, Universität Paderborn, Warburger Str. 100, D-33098 Paderborn
Water splitting is a highly promising environment friendly approach for hydrogen production. It is often discussed in the context of carbon-dioxide-free combustion and storage of excess electrical energy after conversion to chemical energy. Since the oxidation and reduction reactions are related to significant over-potentials, the search for a suitable catalyst is of particular importance. Ferroelectric materials, e.g. Lithium Niobate (LN), attracted considerable interest in this respect. On the one hand, the spontaneous internal polarization results in enhanced life-times of photo-generated charge carriers. At the other hand, the presence of surfaces with different polarization and chemistry leads to spatial separation of oxidation and reduction reactions. Employing DFT and a simplified thermodynamic approach to calculate Gibbs energy differences, we present an efficient method to estimate the over-potentials related to the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) on both polar LiNbO3(001) surfaces. Our calculations show that the OER and HER over-potentials are lower on the negative (1.27 V) and positive (0.39 V) LN surface, respectively. Calculations within the NEB method reveal the barrier height between the intermediate steps of the OER and HER reactions.