| With the development of technology and the improvement of living standards,environmental pollution has been more and more serious,which not only affects the ecological environment,but affects the human life and health.At present,the water pollution is one of the most serious pollution.Therefore,how to deal with the waste water has become the most urgent project of our country.Photocatalytic technology has been shown to be a promising method to solve environmental and energy crisis,because of its convenient and no secondary pollution.Titania（TiO2）nanoparticles are considered to be one of the most excellent photocatalysts for the photocatalytic performance due to its nontoxicite,chemical stability and inexpensiveness.Nonetheless,there are two bottlenecks hinder the photocatalytic applications of TiO2.One is that the pure TiO2 can only absorbs ultraviolet light,which takes up only about 4% of the sunlight,due to its wide band gap,and the other is its high recombination rate of photoinduced electron-hole pairs.Therefore,there is an urgent need for a variety of methods to improve the quantum efficiency and light response range of titanium dioxide.In this paper,the main job is to synthesize TiO2-based photocatalytic materials,and study the photocatalytic performance of Cr（Ⅵ）.The main contents are shown as follows:1.Cerium dioxide composing titanium dioxide nanocomposites were facilely synthesized by one pot hydrothermal method,and their photocatalytic reduction of Cr（Ⅵ）under visible light were studied in detail.SEM,XRD,FTIR were used to characterize the morphology,structure and crystallinity of the materials.Next,a serious of photocatalytic degradation experiment were studied.The visible-light photocatalytic activities enhanced by composing CeO2 with TiO2 and proved to be better than that of pure TiO2 and CeO2.Besides,mechanism experiment,XPS,EPR were used to explore the photocatalytic reduction mechanism and propose a possible mechanism.2.The CYP119 enzyme was loaded onto the CeO2-TiO2 carrier by precipitation to build the enzyme-nanosemiconductor composite photocatalytic system.BET,PL,photocurrent were used to characterize the materials.The results show that the photocatalytic reduction of Cr（Ⅵ）by composites is obviously higher than that of pure enzyme and pure Ce O2-TiO2 nanocomposites.By the study,the best composing conditions were obtained.Then the photocatalytic performance of the matersites prepared under the best composing conditions was detailly studied.3.The TCNT composite materials was prepared by combining g-C3N4 with titanium dioxide.SEM,XRD,FTIR were used to characterize the morphology,structure and crystallinity of the materials.FTIR、EDS mapping and PL showed that g-C3N4 was successfully combined with titanium dioxide.The TCNT composite materials showed a strong photocatalytic reduction of Cr（Ⅵ）.Among all the composites,the TCNT-94 composite material showed the best photocatalytic property.The degradation rate reached 98% in 120 min.Furthermore,the TCNT-94 composite material showed good stability.The degradation rate only decreased 15% after 5 cycles.PL,photocurrent and impedance experments were also used to prove that the separate efficiency of e--h+ and interfacial charge transference of TCNT-94 composite material was highest and fastest,respectively,and the photocatalytic property was also the best.Furthermore,the photocatalytic reduction mechanism was also studied,and a possible methanism was proposed. |
