| Environmental and beautiful living environment has become the focus of modern society.Photonic crystals based structural materials have attracted much attention in the fields of coatings,printing and dyeing as well as engineering applications due to their bright color and green environmental protection.Photonic crystals periodic structure makes it have special photonic band gap,into its inner light in the local area and the slow light photons effect,under the action of multiple light absorption occurred on absorption,which produce structure to the attraction,on this basis to build more structure to the attraction of the material system,such as combining light catalytic function and structure to the attraction function become one of the important direction of this field of research,and new way for preparation of new type of green environmental protection decoration material.Among many photocatalytic materials,TiO2 photocatalyst is stable,non-toxic and has been widely used in commercial applications,but its forbidden bandwidth reaches 3.2 eV.Only 5%of the ultraviolet light in the sunlight can excite the carrier,that is,it cannot achieve a full spectral response.Meanwhile,TiO2 is not easy to be prepared into nanometer microspheres with uniform particle size as the structural unit of photonic crystals,while SiO2 nanospheres are one of the important choices for the color system of photonic crystals structure,and they are characterized by simple preparation process,controllable size and easy surface coating modification.Based on above,this paper combines the traditional SiO2 photonic crystals structurally colored materials with TiO2 photocatalyst,and realizes the multi-functionalization of traditional structural color by constructing SiO2@TiO2 core-shell structure nanospheres.The color development and photocatalytic activity of multi-size SiO2@TiO2 core-shell material system under air and hypoxia conditions were systematically studied.The main research contents and experimental results are as follows:(1)The improved Stober method was used to prepare SiO2 nanospheres with different particle sizes.SiO2 with particle size of 242 nm was selected according to the principle of photocatalysis enhanced by slow photon effect of blue edge,and SiO2@TiO2 nanospheres were prepared by mix-solvent method.By controlling the concentration of TBOT and adjusting the thickness of TiO2 shell,and then yellow,orange and red photonic crystals with iridescent effect were obtained by self-assembly of nanospheres with different particle sizes.When the photonic band gap of SiO2@TiO2 photonic crystals matches the electron band gap,the absorption of light by color materials is enhanced due to the slow photon effect.Especially when the shell thickness is 50 nm,it shows good photoelectric activity(9.5 ?A/cm2)in visible light,and the photocatalytic reaction rate constant is 0.03723 min-1.(2)Black TiO2-x with good photocatalytic performance was prepared by chemical reduction of P25 by NaBH4,and SiO2/TiO2-x amorphous photonic crystals with soft color was prepared by mixing it into SiO2 amorphous photonic crystals as a black additive.It is concluded that the color saturation of structure color can be regulated by controlling TiO2-x ratio.The study found that SiO2 provided a dispersion site for TiO2-x.Compared with TiO2-x,the specific surface area of SiO2/TiO2-x enlarged,the catalytic active sites increased and the photocatalytic performance improved.This synergistic effect with the optical local effect of the pseudoband gap of amorphous photonic crystals enhanced the photodegradation ability of the pigments.(3)The SiO2@TiO2-x amorphous photonic crystals was synthesized by thermal deoxidation of SiO2@TiO2-x nanospheres prepared by the mixed solvent method,which overcame the problem of uneven distribution on the surface of SiO2 nanospheres after excessive TiO2-x was introduced from external source,and the remaining part was agglomerated,affecting the photocatalytic performance and making the color uneven Therefore,the SiO2@TiO2-x nanospheres prepared by mix-solvent method is synthesized by thermal deoxidation of SiO2@TiO2-x amorphous photonic crystals.After vacuum heat treatment of TiO2,disordered layer and oxygen vacancy were generated on the surface of TiO2 crystals,and the white SiO2@TiO2 was changed into the brightly colored SiO2@TiO2-x with angle-independent.Controlling the reduction time not only regulates the color tone,but also the photocatalytic activity.After reduction for 3 h,the sample was enhanced by photonic absorption and electron activation due to the optical local effect of the amorphous photonic crystals and the surface plasmon resonance effect of the oxygen vacancy,making it have better photoelectric activity.Compared with SiO2@TiO2 photonic crystals,the photocurrent reached 38.44 ?A/cm2,and the photocatalytic reaction rate constant was 0.04413 min-1. |
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