Anapole Excitations in Oxygen-Vacancy-Rich TiO2–x Nanoresonators: Tuning the Absorption for Photocatalysis in the Visible Spectrum
| Autor: | Stefan A. Maier, Emiliano Cortés, Javier Cambiasso, Yi Li, Ludwig Hüttenhofer, Alberto Lauri, Evangelina Laura Pensa, Ian D. Sharp, Felix Eckmann |
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| Rok vydání: | 2020 |
| Předmět: |
Technology
Nanostructure Chemistry Multidisciplinary Materials Science Physics::Optics General Physics and Astronomy Materials Science Multidisciplinary 02 engineering and technology Dielectric 010402 general chemistry 7. Clean energy 01 natural sciences oxygen vacancies Condensed Matter::Materials Science chemistry.chemical_compound silver reduction General Materials Science Nanoscience & Nanotechnology Absorption (electromagnetic radiation) Nanoscopic scale Science & Technology TITANIUM-DIOXIDE Chemistry Physical titanium dioxide business.industry anapoles 3RD HARMONIC-GENERATION General Engineering GAP 021001 nanoscience & nanotechnology 0104 chemical sciences Chemistry REDUCTION chemistry Physical Sciences Titanium dioxide Photocatalysis Science & Technology - Other Topics Optoelectronics Photonics dielectric nanostructures 0210 nano-technology business photocatalysis Visible spectrum |
| Zdroj: | ACS Nano |
| ISSN: | 1936-086X 1936-0851 |
| Popis: | Research on optically resonant dielectric nanostructures has accelerated the development of photonic applications, driven by their ability to strongly confine light on the nanoscale. However, since dielectric resonators are typically operated below their bandgap to minimize optical losses, the usage of dielectric nanoantenna concepts for absorption enhancement has largely remained unexplored. In this work, we realize engineered nanoantennas composed of photocatalytic dielectrics and demonstrate their increased light harvesting capabilities in otherwise weakly absorptive spectral regions. In particular, we employ anapole excitations, which are known for their strong light confinement, in nanodisks of oxygen-vacancy-rich TiO2-x, a prominent photocatalyst that provides a powerful platform for exploring concepts in absorption enhancement in tunable nanostructures. We show that by varying the nanodisk geometry, we can shift the anapole wavelength into resonance with optical transitions associated with the sub-bandgap oxygen vacancy (VO) states and thereby increase visible light absorption. The arising photocatalytic effect is monitored on the single particle level using the well-established photocatalytic silver reduction reaction on TiO2. With the freedom of changing the optical properties of TiO2 through tuning the abundance of VO-states we discuss the interplay between cavity damping and the anapole-assisted field confinement for absorption enhancement. This concept is general and can be extended to other catalytic materials with higher refractive indices. |
| Databáze: | OpenAIRE |
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