| Metal oxide nanomaterials have been widely concerned by scientific researchers,due to its advantages,such as nano-size effect,high specific surface area,etc.Among them,In2O3 has become one of the most advantageous light and gas sensing materials due to its wide bandgap,low resistivity and high conductivity.However,In2O3 has the following problems that need to be urgently solved for NO2 detection.The adsorption and desorption process cannot achieve a rapid equilibrium between NO2 gas and sensitive materials at high temperature;the interference of ambient humidity reduces the NO2 gas sensitivity performance at room temperature.In the application of In2O3 photosensitive sensor,the low photosensitive response value and narrow detection range restrict its application.This dissertation focuses on the above issues and the specific work is as follows:(1)Three-dimensional hierarchical porous In2O3 nanomaterials were prepared by hydrothermal method and adjusting the mass ratio of NH4F to In(NO3)3(1:2,1:3,1:4).The results show that In2O3 microcubes can be obtained with high specific surface area and large porosity,providing the large number of active sites and effective transmission channel for NO2 rapid adsorption and diffusion when the mass ratio of NH4F to In(NO3)3 is 1:3.A rapid adsorption-desorption equilibrium of this material can be obtained for 50 ppm of NO2 at 150?within 8 s,and the original resistance state can be completely restored within 10 s.The response value is as high as 2329,and the detection concentration limit can be as low as 10 ppb.Moreover,due to the hydrophobicity of In2O3,its humidity sensitivity response value is only 5.0 when the RH is 80%at room temperature.Under this condition,the gas sensitivity response value of 50 ppm NO2 is still as high as 463(The response value of 50 ppm NO2 is 492 when RH is 20%),indicating that the resulting In2O3 microcubes have moisture resistance at room temperature.(2)Based on the hydrothermal method,three-dimensional hierarchical porous micro cubic In2O3 nanomaterials were prepared by adjusting the heat treatment temperature(600?,700?,800?).The results show that when the heat treatment temperature is 800?,it can be obtained outstanding light response to ultraviolet light with a wavelength of 365 nm.At 25?,the light response balance can be reached within 10 s to 100%p ultraviolet light,and the original resistance state can be restored within 21 s,and the response value can be as high as 10013.However,as the working temperature increases,the response value gradually decreases(the response value is 387 when the working temperature is 200?).Furthermore,at room temperature,In2O3 also has an expansive light response range from 365 nm to 515 mm,and the corresponding response range is 1289 to 10.4,which means that In2O3 is more suitable for UV sensors or detectors.(3)In2O3-ZnO photosensitive composite materials(IZO ?,IZO ?,IZO ?)also were prepared by the solvothermal method.The results show that IZO III has better photosensitivity to 365 nm ultraviolet light,the response value of 100%p ultraviolet light(365 nm)increases to 18372 at 25?,and the response/recovery time is 11/12 s,compared with In2O3 800?.Meanwhile,when the working temperature is 200?,the photosensitive response value is also increases to 854.The photosensitivity values of IZO III to blue light(425 nm)and green light(515 nm)are also raised to 4611 and 38,respectively.The reason of performance improvement of the device is mainly attributed to hybrid ZnO which not only provides more active sites for absorbing ultraviolet light but also promotes the electron transport capacity. |
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