NH3 sensing properties and mechanism of Ru-loaded WO3 nanosheets

In this paper, WO 3 nanosheets were prepared by an acidification method and Ru catalyst was loaded on the surface of nanosheets through a conventional impregnation process. NH 3 gas sensors based on the neat and Ru-loaded WO 3 nanosheets were fabricated by the scree-printing technique and their sensing properties to NH 3 were investigated. The morphologies and surface structures of neat and Ru-loaded WO 3 nanosheets were analyzed. It is revealed that WO 3 nanosheets have an irregular flake shape and Ru catalyst is found on the surface of nanosheets with an oxided state. It is also found that the sensor response of WO 3 is greatly improved by the loading of Ru. Based on the power-law response of oxygen and TPR results, the sensitization mechanism of Ru is explained. It is proposed that the introduction of Ru promotes the catalytic activity of WO 3 and in turn modulates the reaction route of NH 3 with oxygen adsorbates on the surface, which inhibit the generation of nitrogen oxides and consequently reduces the competitive adsorption with oxygen during the sensor responses.