Stady On Preparation And Optical Properties Of Nano-Tungsten Bronze A_xWO₃?A=K,Cs?

Energy is the foundation on which people depend for survival and plays an important role in our daily life.Energy consumption and environmental pollution have become very serious problems with the rapid development of industry.Finding sustainable clean energy has become a research hotspot.The energy of solar radiation is mainly concentrated in the wavelength range of 200-2500 nm,half of which is in the near-infrared range?wavelength range:700-2500 nm?.In recent years,it has been found that nano-alkali metal tungsten green?A_x WO₃,where A=K,Na,Rb,Cs,etc.,0<x<1?has high transmittance in the visible region strong absorption-based shielding performance in the NIR region.Nano-alkali metal tungsten green has a very prominent role in energy conservation and environmental protection.Its near-infrared shielding performance can be applied to the field of thermal insulation coating to maintain the comfortable temperature inside the building and the vehicle,reducing energy consumption.In addition,we use its shielding properties for near-infrared to combine it with UV and visible light photocatalytic materials to prepare a broad spectrum catalytic material with wider light response range and higher energy conversion efficiency.Therefore,the preparation of nano alkali metal tungsten bronze with excellent near-infrared shielding performance is very important for saving energy and reducing environmental pollution.The main research include this thesis are as follows:1.Nano caesium tungsten bronze was prepared by solvothermal method using tungsten hexachloride,caesium hydroxide and acetic acid as raw materials.The effects of different acetic acid addition,precursor stirring time and dispersant Polyvinylpyrrolidone addition on the structure,particle morphology and optical properties of nano caesium tungsten bronze materials were investigated.Through the optimization of experimental conditions,the optimal preparation conditions were obtained:the amount of acetic acid added was 10 ml,the stirring time was 5 min,the reaction temperature was 240?,and the reaction time was 20 h.Under these conditions,nano caesium tungsten bronze nanorods with a visible light transmittance of less than50 nm and a maximum visible light teansmittance of 71.3%and a near infrared transmittance of 14.9%were synthesized.2.Nano cuprous oxide was prepared by liquid phase method using sodium hydroxide,anhydrous copper sulfate and ascorbic acid as raw materials.When the concentration of sodium hydroxide is 0.5mol/L,cuprous oxide is aggregated by small particles with a diameter of 100nm to form nanospheres with a diameter of about700nm,and the uniformity is good.The caesium tungsten bronze was used to prepare nano caesium tungsten bronze/copper oxide composites,and the photocatalytic hydrogen production.performance of caesium tungsten bronze and caesium tungsten bronze/copper oxide was studied.It was found that both the bismuth tungsten bronze and the caesium tungsten bronze/copper oxide have no photocatalytic hydrogen production performance in the pure water and in the pure water with the addition of the promoter platinum.3.Nano potassium tungsten bronze with excellent near-infrared shielding properties was prepared by solvothermal method using tungsten hexachloride,potassium hydroxide and acetic acid as raw materials.The nano-potassium-tungsten bronze prepared by changing the amount of acetic acid added in the precursor solution and the potassium hydroxide/tungsten hexachloride molar ratio is hexagonal,and Except for the strong diffraction peaks of?002?,?200?and?004?,other X-ray diffraction peaks are not obvious.It is possible that the prepared nano-potassium tungsten bronze particles are too small,resulting in a broadening of the diffraction peak.It is also possible that the nano potassium tungsten bronze particles are not completely crystallized and the lattice structure is incomplete.When the amount of acetic acid added is 10 ml and the molar ratio of potassium hydroxide and tungsten hexachloride is 1:2,a sky-blue nano potassium tungsten bronze with near-infrared shielding properties prepared by agglomerating small particles with a grain size of 50 nm or less is prepared.When the sample structure does not change after being left for a while,the color turns white-green and does not have near-infrared shielding properties.After reduction treatment,the sample turned dark blue,and the grain size was distributed in the range of 100 nm,while having near-infrared shielding properties.