Preparation And Gas Sensing Properties Of Semiconductor Metal Oxide Nanomaterials

With the continuous progress of society and the continuous improvement of people's living standards,people are increasingly paying attention to the environmental security around them and their physical and mental health.Sensor is a major industry of modern technology as important devices for information acquisition.As an important branch of sensors,gas sensors have been widely used in the fields of atmospheric monitoring,disaster prevention and alarm,food safety and medical diagnostics.Gas-sensing materials are the core part of the gas sensor,and they are important factors affecting the performance of the gas sensor.Among them,the metal oxide semiconductor gas sensor has attracted people's attention due to its advantages of simple preparation,low cost,and stable performance.This dissertation starts with improving the gas-sensing properties of metal oxide semiconductors.It focuses on the problems of gas sensors in detecting gases.By adjusting the microstructure,noble metal modification and elemental doping,we can improve the sensitivity,selectivity,working temperature and stability of gas sensitive materials.The main research content is as follows:?1?In order to improve the sensitivity of the hydrogen sensor at low temperatures,a three-dimensional sea urchin-shaped W₁₈O₄₉with multi-level structure composed of one-dimensional nanorods was prepared by a simple and efficient hydrothermal method.This kind of structure has a very large specific surface area,which promotes the adsorption of gas,and at the same time increases the diffusion rate of the gas,which leads to a substantial increase in the sensitivity of the device.Then we modified the noble metal Pd nano-particles on the surface by a simple stirring method,further optimized the gas-sensitivity of hydrogen gas based on catalytic effect of Pd on hydrogen gas.?2?Cr-doped a-Fe2O3 nanoparticles were prepared by hydrothermal synthesis.Chromium ions were present in the sample as +3 and replaced the Fe3+ sites in the a-Fe2O3 lattice.4wt%Cr-doped a-Fe2O3 nanomaterial has the highest sensitivity,up to 213 sensitivity to 50ppm H2S at 100? operating temperature.Compared to a pure a-Fe2O3 gas sensor,the sensitivity of the 4 wt%Cr-doped a-Fe2O3 gas sensor is nearly twice,and the sensor's optimal operating temperature is also reduced.