The Preparation Of New-type Photocatalytic Materials Of Inverse Opal Structure And Its Application

Photocatalytic technology is a clean and environmentally-friendly pollution control technology which is expected to utilize solar energy to completely decompose pollutants or directly convert solar energy into other energy.Photocatalytic technology has attracted more and more attention in the past 30 years,but it is still in the stage of theoretical research and experimental exploration,mainly due to its low energy efficiency and limited practical application.In order to solve this problem,this article will combine inverse opal photonic crystal structure and photocatalytic technology together,to improve the efficiency of photocatalysis by limiting,modulating and controlling photons to enhance the absorption of light.This article mainly carries on a few parts of work as bellow:In chapter 2,we used a facile photodeposition method to modify inverse opal TiO2(i.o.TiO2)with cobalt phosphate(Co-Pi),and the resulting composite was applied for photocatalytic reduction of Cr(Ⅵ).In addition,the combination of i.o.TiO2 and Co-Pi achieves high visible light-driven photocatalytic activity,which is better than that of the pure Co-Pi catalyst and unmodified i.o.TiO2.Experimental results demonstrated that the Co-Pi in the composite could absorb a large amount of visible light and then inject electrons into the conduction band of i.o.TiO2 which subsequently participate in the reduction reaction of Cr(Ⅵ).Moreover,the inverse opal structure of the catalyst possesses the advantages of having a large surface area and efficient light harvesting ability,leading to the better catalytic activity of CoPi/i.o.TiO2 than Co-Pi/bulk TiO2 and Co-Pi/P25.It’s also proved that this Co-Pi/i.o.TiO2 photocatalyst can efficiently remove organic pollutants together with Cr(VI).In chapter 3,we combined the g-C3N4 and SiO2 photonic crystal through the monomer polymerization method,and successfully prepare g-C3N4 photocatalyst with inverse opal structure.Then we apply the catalyst into photocatalytic production of hydrogen peroxide.Comparing to g-C3N4 with other structures,the activity of inverse opal g-C3N4 was higher than others.A series of characterization prove that materials with inverse opal structure ha larger surface area that can offer more active sites for O2 adsorption,and periodic holes structure can promote the separation of photo-induced holes and electrons,so that it can have higher photocatalytic activity.In chapter 4,we combined the preparation method of inverse opal TiO2 and inverse opal g-C3N4 and successfully prepare the TiO2/g-C3N4 composite photocatalyst with inverse opal structure.According to the UV-DRS、PL、EIS and Mott-Schottky plots characterizations,we can see the homogeneous dispersion of TiO2 and g-C3N4,and the final product maintained a complete structure of inverse opal.In addition,a series of composite materials with different ratio of TiO2 and g-C3N4 were prepared,and we applied these photocatalysts into dye pollutants decomposition under visible light irradiation.The experimental results showed the optimal composite ratio.And then characterization results illustrate the photocatalytic mechanism of the composite,they proved that the improvement of photocatalytic activity was mainly due to the formation of p-n heterojunction between TiO2 and g-C3N4,it promotes the separation of electrons and holes.