Controlled Preparation Of Tungsten Oxide Micro-/Nano Structure And Its Photocatalytic Properties

Nowadays,environmental pollution is becoming more and more serious.Researchers have conducted extensive and in-depth research to find an effective method to solve this problem.The discovery of semiconductor photocatalytic materials provides scientists with new ideas.Ti O₂ is well known as a common material in this research field,but due to its wide band gap,low visible light utilization rate,liable electron-hole recombination,and difficulty in recycling,its large-scale application is restricted.However,WO₃ photocatalytic material has gradually become a new research focus in this field because of its similar energy band structure as Ti O₂,narrower band gap width,and higher visible light utilization rate.In order to investigate the influence of the morphology characteristics of tungsten oxide micro-/nanostructures on its photocatalytic performance,the controllable preparation of tungsten oxide micro-/nanostructures was realized by hydrothermal method,template method,coprecipitation method,photo-induced reduction method and alcoholysis method.Through photocatalytic degradation of rhodamine B?Rh B?solution,the tungsten oxide micro-/nanostructures with outstanding performance was selected and the corresponding composite materials were further prepared to improve the photocatalytic performance of single structure tungsten oxide.Field emission scanning electron microscopy?FESEM?,energy dispersive spectrometer?EDS?and X-ray diffraction?XRD?technology were used to analyze the morphology,element composition and crystal structure of the tungsten oxide micro-/nanostructures,and the photocatalytic performance of the micro-/nanostructures was tested through the degradation of Rh B solution.In this paper,tungsten oxide with different morphologies such as flower-like microspheres?Nf?,spindle-like nanorods?Nr?,flower-like nanosheets?Ns?,bulk-like nanosheets?Nb?were prepared by simple hydrothermal method with different raw materials as tungsten sources.It can be seen from the photocatalytic test results that the degradation rates of Rh B solution of tungsten oxides with different morphologies solution are quite different,which proves that the photocatalytic performance of tungsten oxide is closely related to its morphological characteristics.By comparing the degradation kinetics curve of Rh B solution,it can be seen that the photocatalytic performance of flower-like tungsten oxide microspheres is superior to other tungsten oxide catalysts.The order of degradation efficiency of the prepared samples Ns,Nr,Nb and Nf is as follows:Nf>Nr>Ns>Nb.At the same time,by comparing the photocatalytic performance of a series of flower-like tungsten oxide samples with different morphologies made by changing the amount of tungstic acid added,it was found that when the amount of tungstic acid was 1.125 g,the morphology and photocatalytic performance of flower-like tungsten oxide microspheres were the best.Silver-loaded flower-like tungsten oxide microspheres were further prepared by the photo-induced reduction method.The photocatalytic performance of the flower like tungsten oxide materials was further improved.The photocatalytic time was shortened to about 50 minutes,and the amount of silver nitrate was 0.04 g.In order to study and improve the photocatalytic properties of single-morphology tungsten oxide materials,polystyrene/tungsten oxide microplates were prepared by the combination of template method and hydrothermal method.Porous tungsten oxide microplates were successfully prepared by heat treatment to remove PS spheres.Under the same photocatalytic experimental conditions,compared with one single-morphology tungsten oxide microplates,the prepared porous tungsten oxide microplates exhibit an improved photocatalytic degradation rate.When the particle size of PS spheres is about 375 nm,the porous tungsten oxide microplates show the best photocatalytic degradation rate.Without the addition of H₂O₂,the photocatalytic time of porous tungsten oxide microplates was shortened by nearly40 minutes compared to single-morphology tungsten oxide microplates.According to the relevant research,it was found that tungsten oxide micro-/nano powder samples are difficult to recover.Magnetic tungsten oxide nanocomposite hollow spheres have been successfully prepared by coprecipitation,template and alcoholysis method.The results of the photocatalytic and the magnetic field separation experiment show that the magnetic composite material solves the problem that the powder sample is not easy to recycle,and shows a good photocatalytic degradation rate.