Synthesis And Motified Performance Of Ta-based Composite Photocatalyst

Semiconductor photocatalytic technology is a promising way to effectively use solar energy to solve the increased energy crisis and water pollution.The key is to the development of environmental-friendly and high-efficiency semiconductor photocatalyst.Thus,the designment and construction of a novel and environmental-friendly photocatalyst will become an important direction to solve the problem of water pollution.Based on the Ta-based semiconductors,including Ta₂O₅ and Ta₃N₅,have a rich electronic structure,good physical and chemical properties and photocatalytic performance.These natures lead to have a good application prospects in the field of photocatalysis.However,the Ta-based semiconductors?Ta₂O₅ and Ta₃N₅?have their own defects such as wide band gap,stability,poor light absorption ability,which results in that they can not be widely used.Therefore,this paper aims to improve the photocatalytic activities of Ta-based photocatalysts.It's assumption that Ta-based semiconductors?Ta₂O₅ and Ta₃N₅?can couple with other semicondutors,which the well-aligned straddling band structures.The interface and synergistic effects bewteen Ta-based materials and other semiconductors were investigated.And the photocatalytic activity and photostability were systematically evaluated.We also discuss the mechanism of charge transport and pollutant photodegradation.The main contents and results are investigated as follows in this paper:?1?Amorphous Ta₂O₅/g-C₃N₄ nanosheet?ATCN?hybrid was firstly constructed by a facile ultrasonic dispersion process.In this way,amorphous Ta₂O₅ nanoparticles anchored evenly onto the surface of g-C₃N₄ nanosheets,forming the intimate interfacial contacts.The as-prepared ATCN composites exhibited significantly enhanced photocatalytic activities for the degradation of RhB compared to pure g-C₃N₄ and amorphous Ta₂O₅ nanoparticles under visible light illumination?? >420nm?.The optimal ATCN-3 photocatalyst possessed the highest visible-light photocatalytic activity?99.14%?and the degradation rate constant was 2.0055 h-1,which was almost 6.2 and 14.9 times as high as those of individual g-C₃N₄ and amorphous Ta₂O₅,respectively.Particularly,ATCN sample had good stability even after four cycles.So this Ta-based composite had good reusability.Interestingly,amorphous Ta₂O₅/g-C₃N₄ nanosheet hybrid showed higher photocatalytic activity than crystalline Ta₂O₅/g-C₃N₄.The enhanced photocatalytic performance was assigned to the synergistic effects including high surface area,enhanced visible light harvesting,efficient interfacial charge transfer and reduced charge recombination.The plausible mechanism for improved photocatalytic properties was elucidated.?2?A novel Ta₃N₅/g-C₃N₄ metal/non-metal nitride hybrid was successfully synthesized by a facile impregnation method.The photocatalytic activity of Ta₃N₅/g-C₃N₄ hybrid nitrides was evaluated by the degradation of organic dye rhodamine B?RhB?under visible light irradiation,and the result indicated that all Ta₃N₅/g-C₃N₄ samples exhibited distinctly enhanced photocatalytic activities for the degradation of RhB than pure g-C₃N₄.The optimal Ta₃N₅/g-C₃N₄ composite sample,with Ta₃N₅ mass ratio of 2%,demonstrated the highest photocatalytic activity,and its degradation rate constant was 2.71 times as high as that of pure g-C₃N₄.The enhanced photocatalytic activity of this Ta₃N₅/g-C₃N₄ metal/metal-free nitride was predominantly attributed to the synergistic effect which increased visible-light absorption and facilitated the efficient separation of photoinduced electrons and holes.The Ta₃N₅/g-C₃N₄ hybrid nitride exhibited excellent photostability and reusability.The h+ and ·OH active spices are indispensible during the process of photodegrading RhB.?3?A simple hydrothermal method has been proposed to produce excellent photocatalytic Z-scheme Ta₃N₅ nanoparticle/anatase TiO₂ hollow sphere composite photocatalyst.The optical,morphological and photocatalytical properties were investigated in details.Interestingly,after coupling Ta₃N₅ nanoparticle with anatase TiO₂ hollow sphere,the composites exhibited the extended spectral response and obviously enhanced photocatalytic activity of decomposing levofloxacin.Particularly,3-Ta₃N₅/TiO₂ photocatalyst possessed not only the high stability and reusablity but excellent photocatalytic performance?94.12%?for LEV degradation as compared to TiO₂ hollow sphere?77.18%?,which could be attributed to the drastically improved separation efficiency of photoinduced carries,porous surfaces and the synthetic effect.According to the analysis of trapping and photocurrent experiment,the Z-scheme photodegradation mechanism were proposed.