Preparation Of Nanoporous Anodic Aluminum Photonic Crystals And Their Photocatalytic Properties

Photocatalytic reaction is a chemical reaction carried out when a substance acts simultaneously with light and catalysts,it incluses a variety of light-driven processes.Among these processes,the driving reaction of solar energy conversion into green chemical energy(oi.e.water splitting for hydrogen energy generation,CO2 reduction.NH3 production and degradation of environmental pollutants)is an effective way to solve environmental and energy problems.Traditional photocatalysts have the shortcomings of low solar energy utilization rate and quantum efficiency,which restricts their development in application field.Photonic crystals(PCs)has great application potential in the field of photocatalysis due to their highly controllable and tuneable light-harvesting capailities.large effective surface area,efficient charge carrier separation and enhanced diffusion of reactive species.However,as the research in this field is on tis inititial stage,people still have insufficient understanding of the mechanism of PCs' light-harvesting effect.How the PC's photonic stopband,periodicity,and the light-confining effects on the absorption rate of photonic crystals photocatalyst is still to be investigated.We used Sinusoidal Pulse Anodization to prepare NAA-?QV photonic crystal,it has a special optical cavity,and TiO2 is deposited on the surface and cavity by the sol-gel method.During the preparation process,the structure of the photonic crystal(i.e.anodization period Tp and cavity anodization time tc)is systematically modified,so that its resonance band is adjusted into the visible spectrum,which is beneficial to the photocatalytic reaction.Using photocatalytic degradation of organic dyes(ie,MO,RhoB and MB)as the probe,the effects of the photonic stopband position of the photonic crystal and the light-confining effects on the photocatalytic performance of the catalyst were investigated.The results prove that the photocatalytic performance of TiO2-NAA-?QVs prepared at tc=15 min is better than that of TiO2-NAA-pQV prepared at tC=5 min.At the same time,the reusability of the catalyst relatived to the photocatalytic performance of the photonic crystal is also discussed.We prepared Broadband-NAA stack structure photonic crystals with different DEPA periods,and accurately design the transmission band of NAA.The obtained Broadband-NAA has a characteristic transmission band,and the number,position and width of the transmission band in the UV-visible-NIR spectrum can be accurately designed.Broadband-NAA was sensitized with TiO2 by-sol-gel method.The photodegradation of three organic dyes(MB.RhoB.MO)can be used as an indicator to identify the enhancement of photocatalysis in Broadband-NAA.The effect of the number of structural periods in the photonic crystal on the absorption rate of the photocatalyst was discussed.The most excellent Broadband-NAA structure for photocatalytic degradation of MB,RhoB and MO is NAA-BBM1-Stack,which was prepared with Tp=600 s.The photocatalytic efficiency of Broadband-NAA photonic crystals may be related to the impurity peaks of the transmission band.The more impurity peaks,the worse the photocatalytic performance of the photonic crystal.Multi-Wave-Pulse photonic crystals with adjustable characteristic photonic stopband were prepared by Multi-Wave Pulse anodization,which overcome the inherent limitations of aluminum anodic oxidation,and found a method to design an effective medium for photonic crystals,and it can directly convert the anodization function into the change of porosity in the photonic crystal,the effect of different anodization parameters on the characteristic photonic stopband of Multi-Wave-Pulse photonic crystals was evaluated,so as to precisely control the filtering characteristics of these photonic crystals.The photonic crystals were infiltrated with different refractive index media,and the effective media of the different anodization function Multi-Wave-Pulse PC were further evaluated.At the same time,it proves that the sensitivity of the Multi-Wave-Pulse PC with a long anodiztion period length(LTp)is relatively high,which creates new ideas for the development of materials for sensing applications.