| The rapid development of science and technology has brought about rapid changes in our lives.But at the same time,humans are beginning to face more problems and challenges.For example,the energy shortages and environmental pollution have became the focus of human concern.In 1972,Fujishima and Honda published a paper on the use of TiO2 electrodes to photo hydrogenate hydrogen production in Nature.They help us open the door to a new world.Semiconductor materials have become a bridge between materials and energy.The use of semiconductors can capture sunlight to degrade dyes,fibers,and organic contaminants in water.The most important thing is that they points the way for people's research.Up to now,TiO2 is still the most promising material in the research of many semiconductor catalysts.It has good stability,non-toxicity,low cost,strong redox ability and wide application prospects.However,TiO2 also has some problems,such as serious carrier recombination,which can only capture ultraviolet light and has no response to visible light.In order to improve the degradation properties of TiO2,people use a variety of materials to modify and compound them.Lots of composite catalyst comprising TiO2 as a main component is formed.At the same time,a variety of composite methods are proposed.With the progress of research work,the carriers transfer path of binary composite catalysts has gradually attracted the attention on researchers.Different structural models have been proposed to binary composite catalysts.Such as hetero junction type,Z-Scheme type.However,the current research work is still controversial about the boundaries of the two.The comparative analysis work of the above two models has not yet been carried out on a large scale.In view of the above research background,this paper uses carbon material to modify nano-TiO2 catalyst.The behavior of carriers is explored while improving its performance.Two structural models were prepared and their physicochemical properties were compared to/with the same conditions.The research contents are as follows:1)Preparation of nano TiO2 photocatalyst by hydrothermal method.The TiO2 particles were modified by two different carbon materials,graphite carbon and C3N4,respectively.Graphite carbon modified TiO2 is TiO2 particles(TiO2-C)coated with carbon layer,and C3N4 modified TiO2 is TiO2-coated C3N4 two-dimensional nanosheet(TiO2-C3N4).The physicochemical properties of the above materials were characterized by means of SEM,XRD,XPS,DRS and the like.Methylene blue was used as a simulated pollutant to explore its catalytic effect under UV-Vis illumination.The effect of calcination temperature of TiO2 on the crystal structure during the preparation was studied.The photoelectrochemical performance of the composite catalyst was analyzed and the optimum ratio of different components in the composite catalyst was determined.A binary composite photocatalyst with greatly improved catalytic performance was obtained and the reaction mechanism of each of the two materials was verified.2)The two binary materials obtained are combined into a three-component catalyst.First,the carbon material is coated with TiO2 particles and then loaded on C3N4 nanosheets to synthesize TiO2-C-C3N4,all-solid indirect Z-Scheme type semiconductor catalyst.The band gap structure of TiO2-C3N4 and TiO2-C-C3N4 materials was analyzed by photoelectrochemical characterization,and the difference between the type-?semiconductor catalyst and the Z-Scheme type semiconductor catalyst carrier transfer under the same material was compared.The performance of the catalyst was judged by catalytic experiments,and the difference in performance under different catalytic mechanisms was verified. |
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