Fabrication And Optical Properties Of Tandem Photonic Crystal Films

Facing the two problems of energy shortage and environmental pollution,the vigorously developing new sustainable energy plays an important role and is the mainstream of scientific research and technological development.Solar energy is one of the key ways to solve these two problems.In photocatalytic materials,TiO₂ is favored by many scholars because of its non-toxic,harmless,low cost and no secondary pollution.However,due to the inherent disadvantages of TiO₂,such as wide photon band gap and easy recombination of electron holes,the photocatalytic effect of TiO₂ is not ideal.Photonic crystals are structural materials with excellent optical physical properties.Their ordered pore structure has a large specific surface area compared with ordinary materials,and their optical properties are well and adjustable.In this paper,a kind of tandem photonic crystal film materials were prepared and are used as a template structure to design and prepare photocatalytic materials?such as tandem TiO₂ inverse opal film catalyst?with adjustable light absorption performance,what could further improve the photocatalytic efficiency of TiO₂.Compared with common catalysts,tandem photonic crystal materials have the following advantages: 1.The principle of tandem photonic crystal structure is expected to realize the full spectrum absorption of solar energy;2.Large specific surface area can provide enough active sites;3.Rich pore structure is conducive to the transport and diffusion of reactants and products;4.Membrane structure is beneficial to the design and effective utilization of photocatalytic reactor.This paper we use methyl methacrylate?MMA?as raw materials,the PMMA with different sizes were prepared by soap-free emulsion polymerization method.The monolayer photonic crystal film was obtained by self-assembly method,then fill in the titanium source solution to PMMAsingle photonic crystal film gap and then aging,finally,we obtained the TiO₂ inverse opal photonic crystal film catalyst after heat treatment.On this basis,we use PMMA microspheres with different sizes for tandem self-assembly,tandem photonic crystal films are obtained.The research focus of this paper is to explore the preparation and size control of PMMA monodisperse microspheres.Self-assembled structured PMMA microsphere photonic crystal film;Preparation of catalyst structure of TiO₂ monolayer inverse opal photonic crystal film and construction of tandem structure by filling PMMA microsphere photonic crystal gap with ti-source precursor solution.The goal of preparing tandem photonic crystal films,the these mainly obtains the following research achievements:1.High quality monodisperse PMMA microspheres were prepared,and the diameter and size of the spheres were regulated.A series of PMMA microspheres of spherical diameter were obtained,which laid a foundation for the subsequent preparation of tandem photonic crystal films with adjustable optical properties.2.The high quality,stability,good single PMMA photonic crystal film was obtained by flow control deposition self-assembly method.The assembly of different conditions on the PMMA colloidal crystals and investigates the influence of film thickness and quality discovered the preparation of high quality and stable condition of PMMA photonic crystal film and film thickness and the number of assembly condition,for the subsequent preparation of tandem photonic crystals and inverse opals photonic crystals lay the foundation.3.Based on the study of the PMMA single photonic crystal film with high quality,tandem photonic crystal film is prepared,the optical properties of photonic crystal film are analyzed,what found that the tandem photoniccrystal films optical properties and the thickness of thin film,the relationship between factors such as the assembly structure,catalyst for further research on tandem photonic crystal films prove a foundation.4.We used sol-gel methods and the PMMA photonic crystal as the template,the influence of the ratio,concentration and impregnation time of ti-source precursor solution on the preparation of TiO₂ inverse opal photonic crystal film catalyst was investigate.It was found that TiO₂ inverse opal film with high-quality could be prepared at the titanium source solution concentration was 13%,dipping 4 min and the alcohol-water ratio was 10:4.