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)-block-poly(propylene glycol)-block-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.