Research On The Controllable Synthesis And Photocatalytic Performance Of Tantalum Oxide-based Nanomaterials

In view of the global energy crisis and environmental pollution and other worrying issues,semiconductor nanomaterials photocatalysis as an efficient use of solar energy advanced technology is emerging.Among them,photocatalytic degradation of organic pollutants,as a rapidly developing science and technology,has attracted more and more attention because of its advantages of high speed and high efficiency in handling pollutants.Various nanometer semiconductor photocatalysts have been explored.The study found that,first of all,many semiconductor nanomaterials with photocatalytic properties,although highly active,have wide band gaps and need to absorb higher energy ultraviolet light to function.However,in nature,ultraviolet light only accounts for 5%,which leads to the extremely low utilization rate of these semiconductor materials for sunlight,and the application of photocatalysis is greatly limited.Secondly,the photogenic carrier recombination rate of nanometer semiconductor materials is very high,which leads to the decrease of quantum efficiency of semiconductor materials.Therefore,how to broaden the spectral response of the semiconductor catalyst and reduce the photogenic electron hole pair recombination so as to effectively utilize the semiconductor nanometer photocatalyst has become a difficult problem for many scientists.In this paper,Ta₂O₅ NPs with super high specific surface area was synthesized by a simple and clean method.The photocatalytic effects of Ta₂O₅ with different morphologies were studied.How to improve the catalytic efficiency of Ta₂O₅was investigated.In the first part,we prepared Ta₂O₅ NPs to improve the photocatalytic efficiency by increasing the specific surface area of Ta₂O₅.Generally,the activity of the catalyst depends mainly on the active sites on its surface,while the active sites are evenly dispersed on the surface of the catalyst.Therefore,the larger the surface area of the catalyst and the more active sites,the stronger its catalytic activity.In this paper,Ta₂O₅powder was prepared by one-step solvent-thermal method.The product was mixed with urea and calcined to prepare nano Ta₂O₅ with porous structure.Using methylene blue as the model pollutant and mercury lamp as the light source,the degradation effect of catalyst under ultraviolet irradiation was studied.The degradation efficiency of organic dyes was evaluated by uv-vis spectrophotometer.The crystal structure of the catalyst was studied by X-ray diffraction?XRD?,and the morphology and size of the catalyst were observed by field emission scanning electron microscope(?FE-SEM?.The photocatalytic activity of nanomaterials in reducing methylene blue?MB?under ultraviolet light was investigated.The effects of catalyst preparation conditions and sintering temperature on the degradation rate of MB were discussed.In the second part,we construct a new nanocomposite material.Carbon nanotubes?CNTs?have attracted extensive attention due to their excellent structure and physical and chemical properties.It has super high porosity and large specific surface area.It can be used as photosensitizer in the case of long light wavelength to provide photocarrier for semiconductor,thus widening the bandgap width of nanometer materials.In addition,carbon nanotubes have a large specific surface area and a certain adsorption,which is more favorable for photoelectron and hole transport.Tantalum pentoxide and carbon nanotubes were combined to obtain a composite material with better performance than the monomer material.With tantalum pentachloride as the precursor and Cs⁺as the structure-oriented agent,the uniform load of tantalum oxide on the surface of carbon nanotubes is realized,which provides a fast channel for electron-hole transport on the surface of composite materials,reduces the recombination rate of electron-hole pairs,and improves the photocatalytic efficiency of nano semiconductor.