One-step CVD growth of ZnO nanorod/SnO2 film heterojunction for NO2 gas sensor

A highly selective and response value NO2 gas sensor depended on ZnO/SnO2 heterojunction was fabricated in one step by chemical vapor deposition (CVD). The ZnO nanorod/SnO2 film heterojunction samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The gas-sensing performances are investigated under different NO2 concentrations, and the sensor has a high response value in the range of 0.05–1000 ppm with values of 370 % for 50 ppm. Meanwhile, the sensor has good selectivity and repeatability to NO2, and the response value of the sensor to NO2 is 5 times that of ethanol, which is the second-best response gas. These results show that it is a feasible scheme to prepare NO2 gas sensor based on ZnO/SnO2 heterojunction by CVD in one step. We believe that the strategy of synthesizing metal oxide with heterostructures based on this method provides a novel insight for the next generation of gas sensors.