Hydrothermal synthesis of two dimensional WO_3 nanostructures for NO_2 detection in the ppb-level

摘要

This work summarizes the preparation of two dimensional WO_3 nanostructures by hydrothermal method and their NO_2 sensing characterization in the ppb level (90-310 ppb). WO_3 ultra-thin nanoplates with 100 nm of lateral size and about 10 nm of thickness were synthesized and characterized. Hydrothermal treatment (180°C, 48 hours) was carried out on tungstic acid which obtained by direct precipitation of sodium tungstate dihydrate in hydrochloric acid. The morphology of the obtained WO_3 was observed by SEM and TEM and their crystal structures were determined by X-ray diffraction (XRD). Thick films (～5μm and 20μm) of the synthesized WO_3 were prepared by screen-printing, the NO_2 sensing characterizations of the sensors in the ppb level (90-310 ppb) were performed under different operating conditions (temperature from 200°Cto 280°Cand relative humidity from 0% to 100%). The sensitivity of the sensors, response and recovery times are reported and discussed.