Gas Sensing Properties of p-Co(3)O(4)/n-TiO(2) Nanotube Heterostructures

In this paper, we fabricated p-Co(3)O(4)/n-TiO(2) heterostructures and investigated their gas sensing properties. The structural and morphological characterization were performed by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy analysis (XPS). The electrical properties of the heterostructure were studied within the temperature range from 293 K to 423 K. Changes in electrical properties and sensing behavior against reducing and oxidizing gases were attributed to the formation of p–n heterojunctions at the Co(3)O(4) and TiO(2) interface. In comparison with sensing performed with pristine TiO(2) nanotubes (NTs), a significant improvement in H(2) sensing at 200 °C was observed, while the sensing response against NO(2) decreased for the heterostructures. Additionally, a response against toluene gas, in contrast to pristine TiO(2) NTs, appeared in the Co(3)O(4)/TiO(2) heterostructure samples.