Enhanced NO2 sensing properties of Zn2SnO4-core/ZnO-shell nanorod sensors

Zn2SnO4-core/ZnO-shell nanorods were synthesized using a two-step process: synthesis of Zn2SnO4 nanorods the thermal evaporation of a mixture of ZnO, SnO2, and graphite powders, followed by atomic layer deposition (ALD) of ZnO. The nanorods were 50–250 nm in diameter and a few to a few tens of micrometers in length. The cores and shells of the nanorods were face-centered cubic-structured single crystal Zn2SnO4 and wurtzite-structured single crystal ZnO, respectively. The multiple networked Zn2SnO4-core/ZnO-shell nanorod sensors showed a response of 173–498% to NO2 concentrations of 1–5 ppm at 300 °C. These response values are 2–5 times higher than those of the Zn2SnO4 nanorod sensor over the same NO2 concentration range. The NO2 sensing mechanism of the Zn2SnO4core/ZnO-shell nanorods is discussed.