Polymer Analogue Ultrathin Nanowires Assembled Into Honeycomb Ordered Porous Film And Its Application

The optically variable films due to their reversible coloration change under stimulations have attractive application prospect in smart windows,monitors,sensors and optoelectronic devices.However,the low optical modulation range is still one of the main problems in the optically variable films.Hence,building an ordered porous film is an effective way to increase transmittance of the optical film.However,there are few reports on the preparation of ordered porous films with a sort of inorganic material.In this paper,a simple,convenient and template-free method is used to fabricate the honeycomb ordered porous film.According to the polymer-like behavior of ultrathin nanowires and electrochromic property of tungsten oxide,ultrathin tungsten oxide nanowires(W18O49 UTNWs)are selected as the object,ultrathin tungsten oxide nanowires are prepared into honeycomb ordered porous film by breath figure method.The W18O49 UTNWs honeycomb ordered porous electrochromic film is induced into the electrochemical energy storage device based on the process of charging and discharging voltage changes,which is expected to realize the visualization of device charging and discharging process.The main results are as follows1.Preparation of ultrathin tungsten oxide nanowires:The ultrathin tungsten oxide nanowires were successfully prepared by solvothermal method in benzyl alcohol with tungsten chloride as raw material and oleylamine as the stabilizer.The diameter of obtained tungsten oxide nanowires are around 2 nm with different length.2.Preparation of W18O49 UTNWs honeycomb porous film:By using the breath figure method,the film with thickness of 100-300 nm were successfully prepared on different conductive substrates.In addition,the different sizes of the pore in the honeycomb porous film can be obtained via controlling the concentration of nanowire and ambient humidity3.Electrochromic performance of honeycomb ordered porous film:The tungsten oxide honeycomb porous film on ITO-coated PET film have high transmittance as 97%in the bleached state and low transmittance as 24%in the colored state,respectively.At the same time,the range of optical modulation can reach 73%(k= 632.8 nm).Compared with drop coating method,the film with the method of breathing pattern possess more excellent optical and electrochemical properties.4.Application of honeycomb porous film in electrochemical energy storage device:The tungsten oxide honeycomb porous film can be used as an anode material of pseudocapacitor.It is observed that the capacitor becomes blue gradually in the charging process and blue of the capacitor gradually fades in the discharging process,respectively.Of course,the color is the deepest when the capacitor is full of electricity.On the contrary,the color is the lightest when the capacitor is totally discharged.