Tungsten trioxide nanosheet can be used to prepare electrochromic film. Some experts have proposed a method for preparing a high photoelectricity tungsten oxide film, specifically:
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Step one: dissolve the tungstate in water to form a tungstate solution, and then add an excess amount of hydrochloric acid and solid heteropoly acid to the obtained tungstate solution, and stir until no precipitation occurs to form a precursor mixture. Wherein, the tungstate is sodium tungstate, potassium tungstate, lithium tungstate or ammonium tungstate; the heteropoly acid is one or more of phosphotungstic acid, phosphomolybdic acid, and silicotungstic acid; the amount of heteropoly acid is 5% to 35% of the molar amount of tungstate.
Step two: add ammonium oxalate as a structure directing agent to the obtained precursor mixture, and depositing the tungsten oxide crystal on the FTO substrate by hydrothermal method after the FTO substrate is used as a carrier. After that, the FTO substrate on which the tungsten trioxide was deposited was calcined, that is, a tungsten trioxide film was formed on the FTO substrate. Among them, the hydrothermal method for depositing WO3 crystals on the FTO substrate is carried out in an autoclave at a controlled temperature of 100-180°C for 10-24h. The obtained film has a monoclinic phase and a nanosheet shape.
