Mesostructured pure and copper-catalyzed tungsten oxide for NO2 detection

Different tungsten oxide mesoporous nanostructures were used as resistive solid state sensor for NO2 gas detection. The electrical characterization revealed that WO3 was sensitive to NO2, even to low gas concentrations, although differences attributable to its structure were observed. The mesoporous material synthesized as a replica of three-dimensional cubic (KIT-6) silica structure showed better and faster response than two-dimensional hexagonal (SBA-15) structure. The introduction of copper as catalytic additive allowed improving both sensor response and response time. X-ray photoelectron spectroscopy (XPS) measurements showed that copper was mainly placed at the material surface as Cu(I).