| Every material in the colorful nature has its own color. Color originates from interactions of natural light with featured microstructures, which include absorption, reflection, scattering and diffraction etc. The color which can absorb certain wavelengths light and originates from electronic structure called chemical color. Meanwhile, color originates from microstructures called physical color. Structural color results from interactions of natural light with featured microstructures which include interference, diffraction and scattering etc. Compared with chemical color, structure color has several advantages such as higher saturation, non-fading if microstructures retain unchanged and environmental friendliness. Investigations on structural colors can not only reveal structural origins and steering strateges but also inspire our design and fabrication of artificial photonic structure.Colorful semiconductors have received much attentions owing to their wide applications in areas including sensor, SERS, analysis, solar cell, polarizer and photocatalyst etc. But many researches mainly focused on the semiconductors with chemical color(eg. Cd S, Cd Se etc.) and the semiconductors display colors by their unique instinct energy band gaps. Ti O2 semiconductors have been widely used in photoelectric transformation and photocatalysis. Under common cases, colorful Ti O2 could be obtained by doping with materials due to the big energy band gap(>3.0 e V). On the other hand, the naked Ti O2 photonic crystals without dopants also display various colors owing to unique photonic band structures, leading to the selective absorbance for visible lights, which imply potential applications of such structural color in photocatalysis.A facile approach was developed to synthesize iridescent Ti O2 films consisted of assembled Ti O2 nanosheets by solvothermal alcoholysis. By adjusting film thickness, these grating-like nanosheets inspire different structural colors, leading to selective adsorption for visible lights. The trapped visible light forms an enhanced optical field to improve the light utilization of guest molecules. The main work can be divided into following 3 parts.(1) The iridescent Ti O2 films were synthesized by solvothermal reaction of Ti foil, Ti source, tert-butyl alcohol and benzyl alcohol. Such Ti O2 films showed enhanced light absorbance ability in certain wavelength. By optimizing Ti source, reaction period, and substrate, the Ti O2 films displayed strongly selective absorbance of lights with characteristic wavelengths. The iridescent Ti O2 films are not only selective absorb visible light, but also selective absorb IR light, which imply potential applications of such structural color in chemistry and physics fields.(2) Discussed the color formation reason and variation of the color. Exclude the reason of chemical doping and explain by structural color. The iridescent colors of Ti O2 films are formed by the combined effect of the thin film interference and optical waveguide mode. Explained the variation of the color by film thickness.(3) The coupling of incident light and structural color on iridescent Ti O2 films inducing a enhanced light harvesting of guest molecules. We explain the result by the following experiments:(a) Photosensitized degradation of Rh B by mono lights, during degradation of rhodamine B under visible light irradiation, the Ti O2 films showed enhanced activity at the irradiation of lights with characteristic wavelengths corresponding to the strong light absorbance.(b) Enhanced photoelectric performance by coupling Au with waveguide light,(c) Enhanced fluorescence of Cd Se QDs by coupling Cd Se QDs with waveguide light. |
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