Enhanced NO2 gas sensing properties of WO3 nanorods encapsulated with ZnO

Abstract

The influence of the encapsulation of WO 3 nanorods with ZnO on the NO 2 gas sensing properties was examined. WO 3 -core/ZnO-shell nanorods were fabricated by a two-step process comprising the catalyst-free thermal evaporation of a mixture of WO 3 and graphite powders in an oxidizing atmosphere and atomic layer deposition of ZnO. Multiple networked WO 3 -core/ZnO-shell nanorod sensors showed the response of 281 % at 5 ppm NO 2 at 300°C. This response value was approximately 9 times larger than that of bare WO 3 nanorod sensors at 5 ppm NO 2 . The response values obtained from the WO 3 -core/ZnO-shell nanorods in this study were more than 5 times higher than those obtained previously from the SnO 2 -core/ZnO-shell nanofibers at the same NO 2 concentration range. The significant enhancement in the response of WO 3 nanorods to NO 2 gas by encapsulating them with ZnO can be accounted for based on the space-charge model.

Enhanced NOx Gas Sensing Properties of Ordered Mesoporous WO3/ZnO Prepared by Electroless Plating

“…Therefore, it is normal that the resistance of senor sharply dropped when the OM‐WO 3 /ZnO‐B sensor was exposed into reductive NH 3 gas. However, the resistance of senor declines when the sensor is placed in oxidizing NO x gas in this study, which is extremely different from the existing related reports …”

Controlled synthesis of monodisperse WO3·H2O square nanoplates and their gas sensing properties

“…WO 3 is believed to be a promising material applied as gas sensor. The investigations on its gas-sensing properties show that it has excellent sensitivity to toxic gas such as C 2 H 5 OH, NH 3 , NO 2 and H 2 S, especially low concentration [37][38][39]. However, the deep study of the influence of the exposure of certain facets on the sensing properties is still limited.…”

Hydrothermal synthesis porous silicon/tungsten oxide nanorods composites and their gas-sensing properties to NO2 at room temperature

“…These oxygen molecules may be directly adsorbed on the surface of WO 3 nanorods by trapping free electrons from the conducting band, then transform into O 2 − and O − (Eqs. (1)- (3)) [34]. It has been confirmed that the number of adsorbed oxygen species will affect the gassensing properties of the sensor [35].…”