An enhanced gas sensor based on SiO 2 @mesoporous MCM-41 core-shell nanocomposites for SO 2 visual detection.

A colorimetric sulfur dioxide (SO ₂ ) gas sensor based on a core-shell composite was developed. The composite was fabricated with a silicon dioxide core and a mesoporous MCM-41 shell (SiO ₂ @MCM-41), and further loaded with a mixture of zinc chloride (ZnCl ₂ ), sodium nitroprusside (SNP) and hexamine as an SO ₂ indicator. The sensing properties of SiO ₂ @MCM-41 toward SO ₂ were measured in solid powder, discs and a gas detection tube (GDT), respectively. Each of these sensing configurations showed a distinct color change from pale yellow to red, which indicates good potential for naked-eye detection of SO ₂ . The limit of detection (LOD) is 2 ppm for SiO ₂ @MCM-41 discs, which indicates high sensitivity to SO ₂ . The performance of GDT suggested a linear relationship between the SO ₂ concentration and the response length of the red portions in a range of 100-1000 ppm. This work shows promising potential of SiO ₂ @MCM-41 as an easy, effective and rapid response sensing material for the in situ detection of SO ₂ .