Construction Of Zinc Oxide-based Inverse Opal Photonic Crystals And Their Properties

An environmentally friendly and healthy living environment has become a basic demand of modern society.Photocatalytic degradation is a technology that uses photo catalysts to effectively degrade pollutants under the action of light and has become an important scientific means in the field of environmental management.Based on the unique ordered porous structure and slow photon effect of inverse opal photonic crystal structure material,it can effectively enhance the light rate,making it play a significant role in environmental protection,photocatalysis,and other fields,and has an environmentally friendly colorless agent color development technology.Zinc oxide(ZnO)is widely used in the field of catalytic degradation of wastewater due to its excellent physicochemical properties.In particular,it has a refractive index of 2.0 and is white,making it an ideal material for constructing inverse opal photonic crystals.However,its use as a structural color and catalyst material suffers from the same problems as other nonmetallic semiconductor oxides,such as low structural color saturation due to incoherent scattering and low catalytic performance due to wide band gap and low light utilization.To address the above problems,in this thesis,ZnO Inverse Opal(IO)structured color films were obtained using polystyrene(PS)microspheres of different particle sizes as colloidal crystal templates,and on this basis,enhanced Ag/ZnO/CeO2 IO and ZnO/CuO composite photocatalysts were prepared by the strategy of the composite construction of heterojunctions with semiconductors and noble metal deposition.The main research contents and results are as follows:(1)PS microspheres of different particle sizes were synthesized by controlling the amount of monomer and initiator using soap-free emulsion polymerization.The PS microspheres were self-assembled by the vertical deposition method,the ZnO IO photonic crystal preparation process was optimized by controlling the variables,and the high-temperature calcination was used to obtain ZnO IO photonic crystals of different pore sizes with regular morphology and orderly arrangement,showing blue,green and red structural colors,respectively.The optical properties of the inverse opal structured materials were investigated with the help of reflection spectroscopy and microscopy techniques.Then the photocatalytic properties were tested by degradation of rhodamine B(RhB)in visible light,and the relationship between the ZnO IO photocatalysts with different pore sizes and the catalytic performance was explored.All the photocatalysts showed enhanced catalytic performance,which was mainly attributed to the morphology modulation that allowed the photocatalysts to obtain a larger specific surface area,providing more reactive sites for the catalytic reactions.(2)Ag/ZnO/CeO2 IO composite photocatalysts were synthesized by in situ reduction of Ag nanoparticles after compounding them with CeO2 based on the advantage of three-dimensional macroporosity of ZnO IO photonic crystals.In this catalyst,the heterojunction constructed by CeO2 and ZnO,the local surface plasmon resonance(LSPR)effect of Ag nanoparticles,and the slow photonic effect of the inverse opal photonic crystal structure synergistically enhance the catalytic ability of the composite photocatalyst.The synthesized Ag/ZnO/CeO2 IO photocatalysts have enhanced catalytic performance,1.8 times that of ZnO IO and 2.7 times that of ZnO/CeO2 IO,respectively.The catalytic mechanism of the Ag/ZnO/CeO2 IO composite photocatalyst was proposed by its photogenerated charge dynamic mechanism as well as the active material capture experiments.(3)ZnO/CuO IO composite photocatalysts were obtained by impregnation method using PS colloidal crystals as templates,and the effect of CuO content on the photocatalytic performance of ZnO was investigated to obtain ZnO/CuO IO composite photocatalysts with stable photocatalytic performance.The ZCIO-5 sample obtained the best catalytic performance by degradation of methyl orange(MO)in visible light,and its degradation rate of MO was 1.4 times that of ZnO IO and 1.5 times that of CuO IO,respectively.The CuO composite improved the problems of wide band gap and low light utilization of ZnO,which can effectively broaden the spectral response range of ZnO and improve the effective separation of photogenerated electron-hole pairs.The composite of CuO can effectively broaden the spectral response range of ZnO and improve the effective separation of photogenerated electron-hole pairs,thus significantly improving the photocatalytic performance.