A novel Pt loading method for WO3 gasochromic film and the morphology control of the film by two-step solvothermal synthesis

Abstract

Controlling the morphology and structure of nanofilms is an important way to improve their properties. Herein, we report a two-step solvothermal method for preparing nanostructured WO3 film composed of single crystal WO3 nanowires, by which much more flexible morphology control than the traditional one-step method is realized. The film prepared by this method combines the morphological characteristics of two one-step films by changing the solution composition during each step. To obtain gasochromic film, a novel method named “charging-immersing” method is used to load catalyst Pt on the WO3 film. In this novel method, WO3 film is first charged and then immersed in the K2PtCl4 solution, reducing Pt nanoparticles from solution. The variation of transmittance, coloring rate (in 4% H2/Ar) and bleaching rate (in the air) of the film synthesized by two-step method at the wavelength of 1000 nm are 76.2%, 4.57%/s and 1.29%/s, respectively. While the properties of two one step films are 69.2% and 40.9%, 2.73%/s and 1.72%/s, 0.063%/s and 1.42%/s, respectively. The combination of morphology leads to the combination of performance advantages because new morphology (thin WO3 nanowires and relatively large Pt nanoparticles) is more conducive to the dissociation of H2 and diffusion of H and O atoms during gasochromism. This study offers a novel strategy for morphology control of nanostructured WO3 film prepared by solvothermal method and loading catalyst Pt on it.