Room-Temperature Fabrication of Pt Nanoparticle-Dispersed Porous Wo3 Gasochromic Switchable Films Using Oxalic Acid

Pt nanoparticle-dispersed tungsten trioxide (Pt-WO3) gasochromic switchable films are fabricated from a precursor solution containing oxalic acid at room temperature without any heat treatment. The color of the fabricated Pt-WO3 films changed between transparent and deep blue states after being exposed to 4% H2-N2 gas and air, respectively, owing to changes in their optical transmittance. The fabricated films exhibit a porous structure containing uniformly dispersed Pt nanoparticles. Furthermore, X-ray photoelectron spectroscopy confirmed the reduction of platinum ions to metallic platinum. Because the fabrication method does not require heat treatment, it is applicable to all flexible polymer sheets with low heat resistance, including acrylic, polyethylene, and polyvinyl chloride sheets. In addition, the novel coating solution prepared in this study allows gasochromic switchable films with good properties to be fabricated using only one type of coating film without layering separate switchable and catalyst films