Enhanced NO_2 gas sensing properties of WO_3 nanorods encapsulated with ZnO

摘要

The influence of the encapsulation of WO_3 nano-rods with ZnO on the NO_2 gas sensing properties was ex-amined. WO_3-core/ZnO-shell nanorods were fabricated by a two-step process comprising the catalyst-free thermal evap-oration 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 ℃. 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 ob-tained previously from the SnO_2-core/ZnO-shell nanofibers at the same NO_2 concentration range. The significant en-hancement 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.