Enhancement of NO2 gas sensing properties of Zn2SnO4 nanorods by ZnO capping

초록

Zn2SnO4-based gas sensors show very poor performance at room temperature despite being able to detect a range of gases efficiently at high temperatures of 600-1,000 oC, which limits their practical use. This study examined the effect of capping Zn2SnO4 nanorods with ZnO on the NO2 gas sensing properties. Zn2SnO4-core/ZnO-shell nanorods were fabricated by a two step process comprising the thermal evaporation of a mixture of ZnO, SnO2, and graphite powders and atomic layer deposition of ZnO. Multiple networked Zn2SnO4-core/ZnO-shell nanorod sensors showed the response of 37.79% at an NO2 concentration of 100 ppm at 50 oC. This response value is 76 times larger than that of bare Zn2SnO4 nanorod sensors at an NO2 concentration of 100 ppm. The substantial improvement in the response of Zn2SnO4 nanorods to NO2 gas by capping by ZnO can be accounted for based on the space charge model.