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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 23: Focus Session: Fermi level engineering of functional ceramics
KFM 23.6: Hauptvortrag
Donnerstag, 21. März 2024, 11:20–11:50, E 124
Designing Transition Metal Oxynitrides for Photoelectrochemical Applications — •Verena Streibel1,2, Laura I. Wagner1,2, Johanna L. Schönecker1,2, Elise Sirotti1,2, Johanna Eichhorn1,2, Saswati Santra1,2, and Ian D. Sharp1,2 — 1Walter Schottky Institut, TU München, Garching, Germany — 2Physics Department, TUM School of Natural Sciences, TU München, Garching, Germany
Transition metal oxynitrides are an emerging class of functional materials with tunable electronic and optical properties. They offer a high potential for tailored materials development since their Fermi levels, energy band gaps, valence/conduction band positions, and surface chemistry can be controlled by adjusting the cation and anion composition. These design opportunities are especially important for photoelectrochemical applications. Here, we discuss our approach to developing transition metal oxynitride thin films as photoelectrodes using reactive sputter deposition. First, we focus on the influence of the anion ratio in the zirconium oxynitride system. At sufficiently high oxygen concentrations, we observe the opening of a band gap in the UV-visible range and the emergence of photoelectrochemical activity for oxidation reactions. Second, we focus on cation substitution in the titanium tantalum (oxy)nitride system.[1] We demonstrate that controlled Ti-doping of Ta3N5 thin films dramatically reduces the concentration of deep-level defects and thereby enhances the photoelectrochemical activity.
[1] Wagner, Streibel, Sharp, et al., Adv. Func. Mat., 2023, 2306539.
Keywords: oxynitrides; PEC; water splitting; photoelectrochemistry; reactive sputtering