Nanoporous WO₃ Gasochromic Films for Gas Sensing

Nanoporous tungsten oxide (WO₃) films have been widely applied in gasochromic and electrochromic windows due to their high hydrogen diffusion ability. However, a high annealing temperature is required to remove the organic template, which may also collapse the structure of the functional materials. As a photocatalyst, the electron holes in the valence band of WO₃ generated after UV irradiation exhibit a high oxidation activity and can degrade organic materials. Here, nanoporous WO₃ films with pore sizes ranging from 10 to 16 nm were prepared through sol–gel methods with poly­(ethylene glycol)-<i>block</i>-poly­(propylene glycol)-<i>block</i>-poly­(ethylene glycol) (P123) as an organic template and WO₃ as a photocatalytic assistant after UV radiation treatment in a low-temperature environment. After UV degradation treatment, P123 was suitably removed, and the orthorhombic structure of the WO₃ film was notably preserved. WO₃ could promote the ultraviolet (UV) degradation process of templates. The prepared WO₃ nanoporous film exhibited a good thermal stability, fast coloring/bleaching and an excellent cycling performance after annealing at 200 °C. Thermal insulation experiments verified that gasochromic windows with nanoporous films achieve a high energy-saving potential.