NH3 sensing properties and mechanism of Ru-loaded WO3 nanosheets

In this paper, WO3 nanosheets were prepared by an acidification method and Ru catalyst was loaded on the surface of nanosheets through a conventional impregnation process. NH3 gas sensors based on the neat and Ru-loaded WO3 nanosheets were fabricated by the scree-printing technique and their sensing properties to NH3 were investigated. The morphologies and surface structures of neat and Ru-loaded WO3 nanosheets were analyzed. It is revealed that WO3 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 WO3 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 WO3 and in turn modulates the reaction route of NH3 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.