Room temperature acetone-sensing properties of branch-like VO2 (B)@ZnO hierarchical hetero-nanostructures

Hierarchical branch-like VO2 (B)@ZnO hetero-nanostructures with highly crystalline ZnO nanorods grown radially on the surface of the VO2 (B) cores have been prepared via a three-step process. Briefly, the VO2 (B) cores were synthesized by a hydrothermal method and the ZnO shells were formed by two steps: the formation of VO2 (B)@ZnO heteroseeds via a surface adsorption process and the heteroepitaxial growth of ZnO nanorods. The effect of the growth time of ZnO nanorods on the microstructure and acetone-sensing properties was investigated. The crystal structure and morphology of the obtained samples were characterized by X-ray diffractometer, scanning electron microscopy and transmission electron microscope. And the gas-sensing properties of the VO2 (B)@ZnO hetero-nanostructures sensors to acetone were evaluated at room temperature. The results showed that the sensor based on the hetero-nanostructures under an optimal growth time has a high gas response, short response (similar to 8 s) and recovery time (similar to 18 s), good repeatability and excellent selectivity to 100 ppm acetone at room temperature. The efficient gas-sensing capability of the hetero-nanostructure sensor is associated with the beneficial effect of the hierarchical hetero-nanostructures with novel VO2/ZnO heterojunction and high surface area value.