| With the rapid development of society and economic strength,energy and environmental problems have become more and more serious.Since entering the industrial age,non-renewable energy has been exhausted and irrational development,resulting in a waste of resources and pollution to the environment.Solar energy,as an inexhaustible energy,has become a research focus of new energy materials,while semiconductor photocatalytic materials can use solar energy to achieve photocatalytic degradation of dye organic matter and photocatalytic cracking of aquatic hydrogen.Therefore,the research of semiconductor photocatalytic materials has great development significance.As a wide band gap semiconductor material(Eg=3.2 e V),Ti O2 has been widely used in the field of photocatalysis due to its advantages of high chemical stability,low cost,non-toxic and high reuse rate.It is one of the most widely studied photocatalytic semiconductor materials.However,Ti O2 has low quantum efficiency,low solar energy utilization rate and no visible light effect,which limits its application to a large extent.The photocatalytic performance of Ti O2 can be effectively enhanced by means of noble metal deposition,semiconductor recombination,ion doping modification,surface photosensitization and surface reduction treatment.In order to effectively enhance the photocatalytic performance of Ti O2,two aspects should be considered.The first aspect is to find ways to increase the utilization ratio of Ti O2 to sunlight,and the other aspect is to find ways to improve the quantum conversion efficiency of Ti O2.Photonic crystal is an artificial structure composed of materials with different permittivity arranged periodically,which is similar to the regulation of electrons by ionic lattice.Photonic crystal can also regulate photons.This shows two characteristics:photon band gap and slow light effect.In the field of photocatalysis,slow light effect of photonic crystal is often used to increase the residence time of photons in materials.In this paper,Ti O2 nanoparticles were prepared by hydrothermal method at high temperature,and then loaded with Ag and Fe nanoparticles.Secondly,in view of the low utilization ratio of Ti O2 to sunlight,inverse opal structure(IO)Ti O2 was prepared.Using polystyrene microspheres(PS)emulsion as template,high-quality opal template(OCTs)with neat arrangement was prepared.Ti O2 precursor was prepared by sol-gel method.High quality IO Ti O2 photonic crystals were obtained by removing opal template after calcination at high temperature.The next work is to load Ag,Fe nanoparticles and BPQDs on the IO Ti O2,to promote the separation of photogenerated carriers,broaden the light absorption range of Ti O2,and improve the utilization rate of Ti O2 to photons.The main work is as follows:(1)Firstly,the heterogeneous Ag-Fe2O3 nanoparticles were successfully prepared by condensation reflux method,and then the Ag-Fe2O3-Ti O2 ternary structure composites were successfully prepared by hydrothermal method in high temperature reactor.The effective combination of Ag-Fe2O3 and Ti O2 was confirmed by HRTEM,EDS element mapping and XPS characterization.Moreover,through a series of quenching experiments,the existence of·OH active species in the photocatalytic degradation process of Ag-Fe2O3-Ti O2 was also proved,and the mechanism of Z-type semiconductor heterojunction was reversely deduced,and the electron migration path of Z-mechanism was proved.The absorption of LSPR caused by Ag nanoparticles was obviously observed by UV-Vis characterization.The photocatalytic activity of Ti O2was significantly improved by synergistic effect of the special electron transport path of Z-type semiconductor heterojunction and the LSPR effect of Ag nanoparticles.Moreover,Rh B dye aqueous solution was used as sewage model to evaluate the photocatalytic activity of the materials.The results show that the ternary system Ag-Fe2O3-Ti O2 has better photocatalytic activity than pure Ti O2 and binary system(Ag-Ti O2,Fe2O3-Ti O2 and Ag-Fe2O3).(2)In view of the low utilization rate of Ti O2 for sunlight,IO Ti O2 powder was successfully prepared in the following work,and the special binding force of IO Ti O2on photons was utilized to increase the retention time of photons in materials.Subsequently,core-shell structure Ag@Fe2O3 nanoparticles were successfully prepared by condensation reflux,and Ag@Fe2O3-IO Ti O2 ternary composites were successfully prepared by mechanical agitation at room temperature.The experimental conditions were mild and simple.In this study,the synergistic effect of slow light effect of IO photonic crystal,special electron transport path of Z-type heterostructure and LSPR effect of Ag nanoparticles is utilized to improve the photocatalytic performance of materials.The dye Rh B was used as sewage model to evaluate the photocatalytic activity of the materials.The results showed that Ag@Fe2O3-IO Ti O2 ternary composite showed excellent photocatalytic performance.(3)We successfully prepared BPQDs with a size of about 5 nm by mechanical peeling black phosphorus crystal(BP)material in NMP solvent,and for the first time,we loaded BPQDs onto the surface of IO Ti O2,and prepared BPQDs-IO Ti O2 by ultrasonic agitation under sealed conditions.The BPQDs-IO Ti O2 was used the synergistic effect of inhibit the photocarrier recombination of heterostructure and the slow light effect of IO Ti O2 to improve photocatalytic performance of materials.The photocatalytic properties of the samples were significantly improved,and 14 m L-BPQDs-IO Ti O2 showed excellent performance in degrading dye Rh B,which was nearly twice as active as P25. |
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