Fabrication and NO(2) gas sensing performance of TeO(2)-core/CuO-shell heterostructure nanorod sensors

TeO(2)-nanostructured sensors are seldom reported compared to other metal oxide semiconductor materials such as ZnO, In(2)O(3), TiO(2), Ga(2)O(3), etc. TeO(2)/CuO core-shell nanorods were fabricated by thermal evaporation of Te powder followed by sputter deposition of CuO. Scanning electron microscopy and X-ray diffraction showed that each nanorod consisted of a single crystal TeO(2) core and a polycrystalline CuO shell with a thickness of approximately 7 nm. The TeO(2)/CuO core-shell one-dimensional (1D) nanostructures exhibited a bamboo leaf-like morphology. The core-shell nanorods were 100 to 300 nm in diameter and up to 30 μm in length. The multiple networked TeO(2)/CuO core-shell nanorod sensor showed responses of 142% to 425% to 0.5- to 10-ppm NO(2) at 150°C. These responses were stronger than or comparable to those of many other metal oxide nanostructures, suggesting that TeO(2) is also a promising sensor material. The responses of the core-shell nanorods were 1.2 to 2.1 times higher than those of pristine TeO(2) nanorods over the same NO(2) concentration range. The underlying mechanism for the enhanced NO(2) sensing properties of the core-shell nanorod sensor can be explained by the potential barrier-controlled carrier transport mechanism. PACS: 61.46. + w; 07.07.Df; 73.22.-f