Gasochromic effect of sol–gel WO 3–SiO 2 films with evaporated platinum catalyst

Abstract

In the present work, the catalyst Pt was evaporated onto the sol–gel WO 3, WO 3–SiO 2 films. These films were annealed at different temperatures and their structures were characterized by infrared, visible near infrared spectroscopy and X-ray diffraction. The coloring kinetics of the films was evaluated. The results revealed that the 0.75WO 3–0.25SiO 2 composite films had faster coloring rates than the WO 3 films. This improved behavior is attributed to the faster diffusion of atomic H resulting from the existence of more absorbed water, more pores, more phase boundaries, and more grain boundaries in the composite films.