Study On Tungsten Oxide / Tellurium Oxide Heterogeneous Nanostructure Gas Sensor

At present,people pay more and more attention to the environmental safety in human life.So the treatment and protection of the atmosphere have been more and more vital.The toxic NO,NO₂ originated from the industrial waste gas and tail gas have led to acid rain,and meanwhile induced the respiratory disease,that is,the nitrogen oxide gas could contaminate the environment and further damage the human health.Therefore,there is a crying need to realize the high sensitive,reliable,rapid detection of nitrogen oxide gas.Tungsten oxide material is an ultra promising gas sensing material.To further improve the sensitive properties of gas sensor based on tungsten oxide,the heterogeneous composition is an effective way.This paper accomplishes a high sensitive,fast response and recovery gas sensor exposed to NO₂,through constructing the hetero-structure of tugnsten oxide and tellurium oxide.The structure of tungsten oxide nanorods modified by tellurium oxide nanoparticles was prepared by two steps.Firstly,tungsten oxide nanorods were synthesized by solvothermal method,followed by the tungsten oxide nanorods modified with tellurium oxide nanoparticles,which was formed by hydrolysis reaction of four tellurium chloride.The nano structure samples were characterized by SEM,XRD and TEM,and the gas sensitive characteristics were further evaluated.The results showed that the working temperature of the gas sensor after the modification of tellurium oxide was reduced from 200^oC to 150^oC.At the same time,the sensitivity of NO₂ gas increased significantly.At the temperature of 150^oC,tungsten oxide/tellurium oxide nanorod surface heterogeneous gas sensor exhibits the characteristics of N type semiconductor with good dynamic response characteristics and good selectivity for NO₂ gas,the sensitivity of 0.1-1ppm NO₂ gas is about 4 times of pure tungsten oxide nanorods.In this paper,the gas-sensitive mechanism of oxidized tungsten oxide/tellurium surface heterogeneity is described,and the influence of the oxidation of tungsten oxide/tellurium n-p heterogeneity on electron transport and its influence on the conductive channel is emphatically analyzed.Based on the material systems of tellurium oxide and tungsten oxide,the structure of heterogeneous nanowires of the vertical quasi-directional oxidation tellurium/oxidized tungsten oxide shell is proposed.The microstructures of SEM and XRD show that the nuclear shell arrays have uniform morphology,and the heterogenous ordered arrays can be widely applied in the field of gas sensing and other related fields.