Research On Preparation Of Micron-scale Photonic Crystal Particles And Their Applications To Enhance Light Absorption Efficiency

Photonic crystal is a kind of special optical materials whose refractive index changes periodically.With photonic band gaps property,light in the forbidden band can't spread in the photonic crystal structure,but is to be totally reflected.Bi₂WO₆ is a new type of semiconductor photocatalytic materials with a narrow band gap width at about 2.7eV.Therefore,it can absorb ultraviolet and visible light,and show good photocatalytic activity.The paper proposed to mix IO-TiO₂ photonic crystal particles with Bi₂WO₆ powder to improve light absorption of Bi₂WO₆ powder and furtherly enhance its absorption efficiency,because light in the forbidden band can be strong reflected by photonic crystal.Firstly,PS opal templates were prepared using mono-dispersed PS microspheres by floating self-assembly method at room temperature.Then,use liquid phase deposition technology to fill in the templates TiO₂,and IO-TiO₂ photonic crystal films were received after the templates were removed.IO-TiO₂ photonic crystal particles were prepared by ultrasonic.Micro-morphology was analyzed by SEM.The result showed that IO-TiO₂ photonic crystal particles were long-range orderly three-dimensional macroporous structures and their sizes were from several microns to dozens of microns.With microscopic spectrum characterization of optical transmission characteristics,IO-TiO₂ photonic crystal particles had obvious photonic band gaps,and forbidden band position moved to the direction of long wave with the size of PS microspheres increased.Then,Bi₂WO₆ powders were prepared by hydrothermal method.The effects of reaction temperature,reaction time,solvents and the ratios of ethylene glycol and water on the micro-morphology and photocatalytic performance of Bi₂WO₆ were investigated.The results showed that Bi₂WO₆ synthesized by the mixture of ethylene glycol and water at 180?for 16h was three-dimensional flower-spherical structure,showing good visible-light photocatalytic activity.Finally,IO-TiO₂ photonic crystal particles were doped into Bi₂WO₆ powders,and RhB was degraded by them under visible light.The effects of band gap position and concentration of photonic crystal particles on the photocatalytic activity of Bi₂WO₆were investigated.The result showed that photonic crystal particles can enhance the photocatalytic performance of Bi₂WO₆.The reason may be that the light in photonic band gap can be strongly reflected by IO-TiO₂ photonic crystal,which lead to that light multiplely scatters in the Bi₂WO₆ powder,so as to improve light absorption of the Bi₂WO₆ powder and then enhance photocatalytic performance.Further study found that enhancement effect was related to band gap position and concentration.The closer the band gap position of IO-TiO₂ photonic crystal particles got to the absorption peak of Bi₂WO₆,the stronger the enhancement effected.Otherwise,when 15mg photonic crystal particles were doped into 50mg Bi₂WO₆,the enhanced effect showed the best.