The Preparation Of Tungsten Oxide Nanomaterials And Their Electrochromic Performance Research

With the development of the society of industry and economy,current urgently needs to solve the problem of environment pollution and energy utilization.Development of energy conservation and environmental protection materials is one of effective methods.electrochromic materials as a kind of energy-saving material has a vast potential for future development.Electrochromic smart glass can be used in constructions,automobiles,airplanes and other vehicles,and can also be used to glare-proof mirror and display device,even for aircraft and military materials.Tungsten oxide electrochromic materials has excellent performance,low cost and research is the most widespread.This paper investigates some simple methods of tungsten oxide thin film growth on FTO surface with three different kinds of tungsten sources and solvents,surfactant and different hydrothermal time.Hydrother mal is a method of low cost and easy operation.Electrochromic devices which composed of nanostructure thin films that have specific surface area and structure stability will show the better electrochromic property.In the experiment,tungsten oxide nanosheets,nano-nets porous structure,nanoplates porous structure,nanorods arrays had been prepared.Different solvents and surfactants were studied about the influence of tungsten oxide morphology.The Composition,morphology and structure of the materials were characterized by XRD,SEM and TEM.And electrochromic properties of devices were tested.The experiment results show that nanoplates porous structure,nano-nets porous structure and nanorods arrays have good electrochromic properties.(1)Tungstate as a source of tungsten,tungsten oxide film grow on FTO conductive glass surface use a simple hydrothermal method.Nanosheet structure and nano-bulk structure were obtained.Nanosheet structure with thickness of about 5-10 nm.The erformance of tungsten oxide electrochromic device was tested by two electrodes.Colored at-2 V and bleached at 1.7 V respectively.The colored state and bleached state of the device had uniform color and good reversibility.The transmittance curves of nanosheet electrochromic device have been tested at 400-800 nm wavelength range.It has a 40% transmittance at 750 nm.We can calculate the colored and bleached time of the electrochromic device.Transmittance change over time can use potential step method.The time required that transmittance change reached 90% at 750 nm wavelength.By computation,the bleached time is about 12 s and the colored tine is about 28 s.(2)WCl6 as a source of tungsten,In ethanol,tetrahydrofuran and its two kinds of mixed solution respectively.Hydration tungsten oxide thin films were growth on FTO glass surface with seeding layers make use of solvothermal method.Tungsten oxide thin films were got after annealing.And assemble into electrochromic devices.Nano-net porous structure and nanosheet porous structure were produced respectively,and its size is approximately 200-300 nm.In addition nano-bulks and nanowires were obtained.1M Li Cl O4 propylene carbonate solution as electrolyte.The performance of electrochromic devices were tested.Reticular porous structure and nanosheet porous structure can increase the specific surface area,and in favor of Ion intercalation/extraction.They have better general properties.Transmittance of nano-network structure device reached 65%,and transmittance of nanosheet device reached 55%.According to data,the response time of nano-network structure device coloration and bleaching is 15 s and 12 s,and the response time of nanosheet structure device coloration and bleaching is 22 s and 14 s.(3)WO3·0.33H2 O thin films were growth employ hydrothermal method directly on FTO glass surface used ammonium tungstate.On different hydrothermal time and concentration of hydrochloric acid has been discussed.Electrochromic properties of devices were tested.Tungsten oxide has nanocube-rodlike array strycture.They were vertical growth on FTO glass surface.The diameter of nanorod was about 10 nm.The greatest transmission of device at 700 nm wavelength range,and modulation amplitude is 40%.The response time of nanorods structure device bleaching and coloration is 10 s and 18 s.