Gas Sensing Characteristics of WO3 (III)

Details: Category: Tungsten Information; Published on Thursday, 05 February 2015 18:04; Written by cq; Hits: 1375

(3) Gas sensing characteristics to organic gases ( acetone, ethanol etc.)

The morphology of the materials could be designed in the stage of hydrothermal reaction. Some scholars employed a novel hydrothermal process to synthesize plateshaped WO3 nanostructures. The addition of structure-directing agent p-nitrobenzoic acid results in the formation of WO3 nanoplates. The pH value in the reaction system may cause the nano-plate etched partially so that some nanoplates become incomplete with rough edge regions or a hole in the middle. The voltage levels up quickly in presence of ethanol or acetone and restores soon after removing the gases. It demonstrates that the as-prepared WO3 nanoplates have good sensitivity and reversibility to ethanol or acetone. However, the working temperatures are relatively high (340℃ and 370℃) . These temperature values bring lot of difficulties for the actual application of WO3-based gas sensors.

Besides, Another scholars have successfully synthesized large-scale Co-doped h-WO3 nanorods by a facile hydrothermal method with Na2WO4·2H2O and Co(NO3)2·6H2O. They found the nanorods grown vertically from the center towards two opposite directions and had a uniform thickness of about 10 μm. Sensing responses of samples towards a series of typical organic solvents and fuels had been investigate. It is well known that WO3 is less sensitive to hydrocarbons. Whereas, it is noticed that Co-doped WO3 nanostructure is highly sensitive to these flammable organic gases. This illustrates that dopant endows WO3 with better sensing performance towards hydrocarbon gases.

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