Preparation Of Opal Photonic Crystals With Bi₂WO₆:Yb³⁺,Tm³⁺ Photocatalytic Properties

Into the twenty-first century,With the rapid development of today's society,Environmental problems are also growing,How to control and control pollution has become an important topic of sustainable development in today's society?Titanium dioxide was the first photocatalyst to be exploited,Its use means that we have opened the door to photocatalysis,Titanium dioxide is highly active,However,due to its large gap width,the narrow light response range makes solar energy utilization too low,It severely limits its widespread use.So the researchers focused on the development of high-efficient semiconductor photocatalyst,and the new semiconductor photocatalyst,such as bismuth tungstate,entered the field of vision.In this paper,the preparation and preparation of three-dimensional opalite photonic crystals and the preparation of bismuth tungsten-bismuth nanocrystals and the doping of rare earth ions are introduced to enhance the photocatalytic effect.The details are as follows:?1?PS microspheres and PMMA microspheres were prepared by the non-soap emulsion polymerization method,and then by using peristaltic control vertical deposition self-assembly?FCVD?method,PS opalite photonic crystals and PMMA opal photonic crystals were prepared respectively.In this paper,the photonic crystal of opal is analyzed,and the two kinds of opal photonic crystals have colorful butterfly patterns.It can be seen from the scanning electron microscope image that the two kinds of opal are layered structures arranged in order by the uniform size of nano-sized microspheres.From the transmission spectrum,the transmission rate of opal photonic crystal is high,the optical performance is good,and the photonic band gap can reach 20%.?2?The pure Bi₂WO₆ colloid was prepared by the sol-gel method as the chelating agent of EDTA,and the pure phase of bismuth tungstate powder was obtained by 450?4h sintering.Hydrothermal method was used to prepare Yb³⁺,Tm³⁺doped Bi₂WO₆ and pure Bi₂WO₆.The XRD test showed that the diffraction peaks of the samples prepared by the two methods were corresponding to the characteristic peaks of the standard CARDS,and the crystallinity was good,indicating that the doping of rare earth ions did not affect the crystallinity of Bi₂WO₆.Element analysis showed that Yb³⁺and Tm³⁺were incorporated into Bi₂WO₆.?3?Yb³⁺,Tm³⁺doped Bi₂WO₆ nano-powders are converted to light at 455nm,480nm,656nm and 686nm at 980nm infrared excitation,Under the excitation of980nm laser diode,the samples present the green and red emissions around 455nm,480nm and 686nm,corresponding to ¹D₂?³F₄?455nm?,¹G₄?³H₆?480nm?,¹G₄?³F₄?656nm?and ³F₂?³H₆?686nm?energy level transition process,when the doping concentration is Yb³⁺:Tm³⁺=3%:1%the upconversion will be the strongest.?4?Using methylene blue as the probe for Yb³⁺,the doping of Tm³⁺can enhance the photocatalytic ability of Bi₂WO₆ in visible and infrared light.The test results showed that the degradation rate of pure Bi₂WO₆ was 75%,rare earth Yb³⁺,and the highest degradation rate of Tm³⁺doping was enhanced by 90%photocatalytic effect.And the enhancing mechanism is analyzed,mainly including glow on conversion process,rare earth doping enhanced the specific surface area of pure Bi₂WO₆ and rare earth doped better enhance the separation of electrons and holes,and so on.