Synthesis And Gas Sensing Properties Of ZnO Nanorod Arrays

Oriented growth of semiconductor metal oxide nanomaterials has received extensive attention from researchers due to its simple synthesis method,growth tunability and high reproducibility of nanostructure morphology.At present,common semiconductor metal oxides with oriented growth are ZnO,Sn O₂,Ti O₂ and Cu O.Among them,ZnO nanomaterials have a variety of highly ordered nanostructures,such as nanorods(NRs),nanowires(NWs)and nanotubes(NTs).These nanostructured ZnO have many characteristics,including large specific surface area,high electron mobility,and a large number of surface-active centers.Therefore,orientation-grown ZnO nanomaterials become an excellent candidate material in the field of gas sensor manufacturing.In this work,a hydrothermal method is used to prepare a ZnO nanorod array film on the ZnO nanoparticle seed layer,and it is used for the gas-sensitive detection of NO_x at low temperature and some meaningful research results have been obtained.The main research results are as follows:(1)A ZnO nanoparticle seed layer was prepared on an ITO substrate by static spin coating.Finally,ZnO nanorod array thin films were prepared by hydrothermal method.Then the structure and morphology of the prepared sample were characterized,and study the gas sensitivity of the material to NO_x.Experimental test results show that at a working temperature of 120°C,when the NO_x concentration is 3 ppm,the response is 25.(2)In order to change the morphology of the ZnO nanorod arrays film,the ZnO nanorod array thin films obtained by adding PEI and KCl in the growth solution of precursor.Subsequently,the structure and morphology of the ZnO nanorod bundle arrays film were characterized and used for the gas-sensitive detection of NO_x at low temperature.The test results show that at a working temperature of 120°C,when the concentration of NO_x is 0.1 ppm its response,response time and recovery time are 4.5,105 s and 334 s,respectively.(3)In order to improve the gas sensitivity of the ZnO nanorod arrays film to NO_x,aluminum nitrate was added to the growth solution to synthesize an Al-doped ZnO nanorod arrays film.The gas-sensitive of the 6wt%Al-doped ZnO nanorod arrays film to NO_x under low temperature conditions was tested.At 120°C,when the target gas concentration is 3ppm,the gas-sensitive response obtained is 68.This result shows that Al-doped ZnO can significantly improve the gas sensitivity of ZnO nanorod arrays film to NO_x at low temperature.