TiO<sub>2</sub> metasurfaces: From visible planar photonics to photochemistry.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31701001.
- Also identified by DOI 10.1126/sciadv.aax0939 and PMC identifier 6824849.
- Licence recorded as CC BY-NC.
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Abstract
TiO<sub>2</sub> metasurfaces have been intensively studied in the past few years. To date, the TiO<sub>2</sub> metadevices only used their high reflective index (<i>n</i>). The controllable light extinction coefficient (<i>k</i>) of TiO<sub>2</sub> has not been exploited yet. Here, we converted TiO<sub>2</sub> metasurfaces to black TiO<sub>2</sub> metasurfaces and explored their new opportunities in photochemistry. A complementary metal oxide semiconductor (CMOS)-compatible technique has been developed to reversibly and precisely control the absorption of TiO<sub>2</sub> metasurfaces without spoiling their internal nanostructures. Consequently, two types of black TiO<sub>2</sub> metasurfaces were realized for photochemical experiments. The metasurface with an ultrawide absorption band can substantially enhance the white light absorption and accelerate the solar-based photochemistry process by a factor of 18.7. The other metasurface with an absorption band of <20 nm only responded to the resonant wavelengths, making the photochemistry process capable of being monitored in real time. In addition, the reversible switch between normal and black states makes TiO<sub>2</sub> metasurfaces suitable for dynamic metadevices as well.