Synthesis Of Tungsten Bronze Series Photocatalytic Materials With Infrared Shielding Function

Most of the heat in the solar spectrum comes from the near-infrared region?780 nm-2500 nm?,and the illumination is mainly in the visible region?400 nm-780 nm?.Infrared shielding material is a new material that can shield infrared light while maintaining high visible light transmittance.It has extensive applications in energy conservation and environmental protection,especially in the insulation of automotive and architectural glass windows.Tungsten oxides and tungsten bronzes with variable valences are widely used in near-infrared shielding and heat insulation films because of their high transmittance in visible light and shielding performance in the entire near-infrared band.Photocatalysis is the main way to purify environmental pollutants.Using ultraviolet or visible light to irradiate semiconducting nanomaterials can degrade organic contaminants in air or water solutions and achieve the goal of purifying the environment.The combination of photocatalytic properties and infrared shielding properties produces multifunctional nanomaterials that are used on the surface of various glass films.This film has the function of photocatalytic environmental purification and also has the infrared shielding performance.It has obvious advantages in the application of smart windows,and it is expected to achieve energy saving and consumption reduction,environmental purification,and efficient use of solar energy.In this study,a simple,environmentally friendly solvothermal synthesis methodwasusedtopreparetungstenoxideW₁₈O₄₉and alkaline-earth-metal-doped tungsten bronze using lower-cost raw materials.The effects of different raw materials,surfactants,solvothermal reaction time and reaction temperature on the structure and properties of tungsten oxide materials were studied.Through the control of the particle size of the material morphology,the new function of the nanomaterial is effectively provided,and a highly transparent film modulation technology is established.The microstructures of the as-synthesized materials were characterized by XRD,SEM,XPS and BET.Characterization of Near Infrared Shielding Properties of the Films Prepared by UV-Vis DRS,And its degradation of methyl orange and thermal insulation properties were tested,and the degradation of methyl orange was investigated.The specific work is as follows:The first part:W₁₈O₄₉ nanocrystals were prepared by solvothermal method using tungsten carbide as tungsten source,absolute ethanol as solvent,and four surfactants.The influence of solvent type and surfactant on the crystallinity and morphology of the material was studied.The results show that the crystallinity of W₁₈O₄₉ nanocrystals is the best when ethanol is used as a solvent,and the synthetic sample has the best near-infrared shielding performance,and the transmittance in the infrared region is 33.33%.Although the surfactant does not participate in the reaction,the addition of the surfactant will have a greater impact on the morphology of the sample.After the addition of the surfactant CTAB,the W₁₈O₄₉ nanocrystal has a quadrangular sheet-like nanostructure with a specific surface area of 89.15 m²g^-1.After 120 min irradiation at?>400 nm,the degradation rate of methyl orange degradation by W₁₈O₄₉ reached 28%;the visible light transmittance of the film can reach 80%,and the transmittance in the near infrared region is only 30%.It is a kind of transparent heat insulation film with good performance.The second part:The hydrothermal synthesis method was used to prepare M_xWO₃?M=K⁺,Na⁺,Cs⁺?tungsten bronze nanomaterials using sodium tungstate and alkali metal salt as raw materials.The effects of hydrothermal reaction time,temperature and precursor concentration on the phase and properties of tungsten bronze were investigated in the experiment.The study found that when the atomic ratio of raw materials Na/W,K/W,and Cs/W were 6,6,and 8,respectively.And the reaction temperature 200?,heating 24 h,The specific surface areas of the synthesized samples Na_0.33WO₃?K_0.33WO₃,and Cs_0.32WO₃ were 88.26 m²/g?24.24 m²/g,and 85.82 m²/g,respectively.The difference in transmittance(T_vis-T_NIR)between the visible and near-infrared regions was 35.47%,44.97%,and 51.6%,respectively.The prepared nanocrystalline Cs_0.32WO₃ is a porous particle with the smallest particle size,a pore diameter of 11.36 nm,and a maximum?T.Thermal Insulation Properties of Three Tungsten Bronze Materials Cs_0.32WO₃>K_0.33WO₃>Na_0.33WO₃.The heat insulation performance of Cs_0.32WO₃ is the best,and the temperature increase in the light of 600 s is only 27.3%of the blank glass.The tungsten bronze series nanomaterials prepared in this study can achieve near-infrared light shielding,can be applied to new smart windows,realize visible light transmission through the sun light spectrum and simultaneous infrared light shielding,and at the same time the use of its effective absorption of infrared light can achieve environmental purification,achieve multi-functional environmental response characteristics of nanomaterials,and achieve innovation and material value-added.