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MM: Fachverband Metall- und Materialphysik

MM 20: Poster session II

MM 20.31: Poster

Dienstag, 2. April 2019, 18:30–20:00, Poster C

Enhancing photocatalytic efficiency of substoichiometric TiO_x at visible wavelengths using nano-resonators with anapole modes — •Ludwig Hüttenhofer¹, Felix Eckmann², Javier Cambiasso³, Evangelina Pensa³, Yi Li¹, Emiliano Cortes^1,3, Ian D. Sharp², and Stefan A. Maier^1,3 — ¹Nanoinstitut Ludwig-Maximilinas-Universität, Königinstraße 10, 80539 München, Germany — ²Walter-Schottky-Institut Technische Universität München, Am Coulombwall 4, 85748 Garching, Germany — ³Centre for Plasmonics and Metameterials Imperial College, 180 Queen’s Gate, SW7 2AZ London, United Kingdom

TiO₂ has been shown to be a good candidate as photocatalyst also allowing for for water splitting. On the other hand the semiconductors band gap only harvests the small UV portion of the solar spectrum. To permanently turn the material absorptive in the visible spectral range the material is annealed at vacuum. This induces oxygen vacancies in the TiO₂ giving rise to sub-bandgap states (OV-TiO₂). In this work we shape OV-TiO₂ into nano-disks exhibiting anapole resonances. This mode is characterized by a minimum if its far-field scattering and a maximum of electric energy inside the resonator. The goal of this work is to show that by varying the nano-disk geometry we can spectrally locate the anapole resonance within the oxygen vacancy states and therefore maximize the absorption. As a proof of concept study we want to demonstrate the exploitation of anapole modes by the preferred reduction of Ag on the resonant disks surface under 532nm laser excitation on a single particle level.