Preparation of room temperature NO ₂ gas sensors based on W- and V-modified mesoporous MCM-41 thin films employing surface photovoltage technique

W- and V-modified mesoporous MCM-41 thin films were investigated as an NO ₂ gas sensor operable at room temperature employing surface photovoltage (SPV) technique. The self-ordered and structure-controlled of W- and V-modified mesoporous silica MCM-41 were prepared by a molecule surfactant template method using spin coating. The resulting thin films were then applied as a SPV NO ₂ gas sensor based on a metal-insulator-semiconductor (MIS) structure. The W- and V-modified mesoporous silica were highly sensitive to a low concentration of NO ₂, as low as 350 ppb, at room temperature. The mechanism of NO ₂ detection is attributed to both the surface area, which is contributed to the change of dielectric constant, and the amount of the tungsten and vanadium incorporated, which is contributed to the change of semiconductor surface charge. The W-modified mesoporous MCM-41 was found to have better sensing properties than those of the Sn- and V-modified mesoporous MCM-41.