ИСТИНА

Gas sensors based on wide-gap semiconductor metal oxides can detect hazardous impurities in air: NOx, CO, volatile organic compounds (VOC). Adsorption and redox interaction of gas molecules on the materials surfaces controls the sensing behavior. It depends on surface active sites, metal-oxygen bonding and chemical composition of the oxides. Although these correlations are unobvious, finding them is prosperous for the design of novel sensor materials with improved selectivity. In this work, we comparatively studied sensing materials Bi2WO6 and WO3. Electronic properties and metal-oxygen bond energy were calculated by density functional approach. Nanosized Bi2WO6, WO3 and composite Bi2WO6+WO3 materials were synthesized. Bi2WO6 had improved sensitivity to reducing gases (CO, VOC); on the contrary, WO3 was highly sensitive to the oxidizing gas NO2. Effect of W-O bond energy and charge distribution on the sensitivity and selectivity of Bi2WO6 and WO3 were rationalized.