Synthesis And Performance Research Of Low-dimension Tungstate Nanomaterials

Over the past decades,the environmental deterioration has become a worldwide issue because of the rapid development of industrialization and soaring population.In order to remedy the environment,most researchers have developed advanced technologies with low-cost and high efficiency to degrade the pollutants.However,most photocatalysts have a wide band gap,low utilization of solar energy,and high recombination rates of photogenerated electrons and holes,which inhibit their photocatalytic efficiency.Therefore,it is urgent to address these problems by designing the photocatalysts with high efficiency for a sustainable future.In this work,a variety of tungstate nanomaterials with different one-dimensional morphologies were prepared by electrospinning technology combined with heat treatment process.Meanwhile,The Z-type,p-n type semiconductor heterojunction and metal Ag greatly enhance the photoelectric performance and improve the photocatalytic performance.The main research contents are as follows:1.Hierarchical Z-scheme WO₃/Bi₂WO₆ nanotubes have been rationally designed and fabricated via a combined electrospinning-calcination process.Moreover,the morphology of as-fabricated nanotubes could be tuned by the annealing temperature.WO₃/Bi₂WO₆ nanotubes with uniform diameter of 800 nm are wrapped by ultrathin nanosheets,whose thicknesses are around 20 nm.Hierarchical Z-Scheme system highly facilitates the separation and migration of photoinduced charge carriers,and enhances the broadened absorption range and high redox capacity owning to the synergistic effects of WO₃ and Bi₂WO₆.The results demonstrated that 550°C-WO₃/Bi₂WO₆nanotubes exhibit the remarkable photoelectrochemical activity and photocatalytic performance for degrading pollutant models benefiting from the unique structural features.2.Hierarchically porous WO₃/Cd WO₄ fiber-in-tube nanostructures with three accessible surfaces(surface of core fiber,inner and outer surfaces of the porous tube shell)have been prepared by a facile electrospinning method.The WO₃/Cd WO₄heterostructure assembled of interconnected nanoparticles displays improved photocatalytic activity compared to WO₃ or Cd WO₄ for the degradation of ciprofloxacin and tetracycline,an antibiotic probe,under simulated sunlight irradiation.The unique fiber-in-tube nanostructure promotes the separation and migration of photoinduced charge carriers,and provides abundant catalytically active sites for photocatalytic reactions.The Z-scheme photocatalytic mechanism over such unique WO₃/Cd WO₄ fiber-in-tube is investigated by both active species trapping experiments and electron paramagnetic resonance.The synthesis of a fiber-in-tube nanostructure has been demonstrated that shows effective application in the photocatalytic degradation of an antibiotic in water.3.Nanostructured heterojunctions with remarkable electron-hole separation efficiency and good optical properties are crucial for the ability of photocatalytic degradation.Herein,porous nanotubes Ag-Co WO₄/Cd WO₄ plasmonic photocatalyst with remarkable visible-light response capability have been fabricated through the combining of electrospinning and deposition.The ability of photocatalytic degradation levofloxacin with Cd WO₄ can be significantly improved by constructing p-n heterojunctions and addition of trace amount silver nanoparticles.The appreciable performance improvements are caused by the formation of p-n heterojunction,Ag nanoparticles as well as one-dimensional porous nanotubes.Especially,Ag modification can not only extend the range of visible light response but also greatly increase the separation and transfer rate of charge carriers because of surface plasmon resonance effect of metallic Ag.The radicals trapping experiments and electron paramagnetic resonance demonstrated that high generation rate of species due to surface plasmon resonance effect induced by the Ag nanoparticles can preserve the strong redox ability.Moreover,the transformation products in water and degradation pathways of levofloxacin were proposed by mass spectrometry.Ag modified porous Co WO₄/Cd WO₄ nanotubes enhance light absorption and charge separation,boosting the activation of samples to generate reactive radicals for fast levofloxacin mineralization.