Preparation Of V₂O₅-based Hollow Microspheres And Research On Its Gas-sensing Properties

As a typical n-type semiconductor of metal oxide material,V2O5 has attracted immense research interest due to its unique layered structure and oxygen vacancy in gas sensing detection field.The synthesis of different nanostructures and modification are particularly attractive.V2O5 was studied as gas sensing material in this thesis,including the synthesis,structure characterization and the gas sensing performances of hierarchical V2O5 hollow microspheres and its modified nanocomposites materials of Zno/V2O5 and NiO/V2O5.The main results are as follows:1)The monodisperse hierarchical V2O5 hollow microspheres were synthesized by a template-free solvothermal method followed by calcination at 400 ℃ for the first time using VO(acac)2 as raw material.The diameter of the hollow microspheres were around 200-250 nm with the thickness of 40～50 nm,in which the building blocks were the cube-like morphologies with the length of 80 nm,the width of 30 nm.The sensitivity of such hollow microspheres to 100 ppm and 1000 ppm ethanol was 2.1 and 4.36,showing better selectivity to ethanol in 330 ℃.2)The uniform hierarchical ZnO/V2O2 hollow microspheres with good dispersity were synthesized through a template-free solventhermal method using VO(acac)2 and Zn(acac)2 as raw materials combined with 500 C calcination.The diameter of the hollow microspheres was around 500 nm while the shell thickness was 40-50 nm,the building blocks of the surface were nano-particles with diameters of 30-50 nm.The sensitivity of 10 mol%ZnO/V2O5 microspheres with respect to 100 ppm methanol was 4.21 at 290 C.When the working temperature was lowered to 135℃,ZnO、V2O5 sensors with 5 mol%and 10 mol%ZnO ratio showed higher sensitivity to 1-propyl alcohol and methanol respectively,meanwhile these sensors showed good stability after repeated trails.3)The monodisperse NiO/V2O5 double-shell microspheres were synthesized through a simple template-free solventhermal method using VO(acac)2 and Ni(acac)2 as raw materials combined with 500℃ calcination.The diameter of the microspheres was around 500-600 nm,while the building blocks were nano-particles and nanosheets.The selectivity of the sensor to ethanol can be improved by adding NiO into the V2O5 micropheres,which can also lower the working temperature by 120℃.The sensitivity of NiO/V2O5 double-shell microspheres to 100 ppm ethanol at 210℃ was 4.42,it could detect ethanol vapor as low as concentration of 0.1 ppm.