Study On Preparation Of One-Dimensional WO₃ Nanowires And Optimizing Its Gas Sensing Performance

The existence of harmful gases in the air will pose a threat to people’s production,life,and even the safety of all living organisms.Therefore,we need to monitor the air quality real-time and effectively.Driven by intelligent manufacturing in the era of industry 4.0,sensors are regarded as the foundation of the"Internet of Everything",it is challenging to develop gas sensing devices with high gas sensing performance,low power consumption.For this reason,various gas sensors have been reported by the researches,for example,gas sensors based on metal oxide semiconductor（MOS）materials have the characteristics of high sensitivity,easy preparation,low cost,and miniaturization,which have attracted extensive attention of researchers.However,the sensors based MOS generally require high operating temperature,or the poor selectivity,which bring high power consumption and certain safety hazards,need to be solved urgently.Therefore,improving the gas sensing performance by functionalizing the materials is very necessary.As a typical n-type semiconductor material,tungsten trioxide（WO₃）has great application potential in the gas sensing research area.This paper mainly focuses on the preparation of one-dimensional WO₃nanowire materials and the functionalization of its surface to obtain better gas sensing properties.The gas-sensing mechanism is explained through the investigation of SEM、TEM、XRD、Raman、XPS.The research contents and results obtained in this paper are as follows:1.The WO₃/WS₂heterojunction is realized through One-dimensional WO₃nanowire vulcanization treatment.One-dimensional WO₃nanowires were prepared by electrospinning,then WO₃was vulcanized,additionally the effects of vulcanization parameters on its morphology,surface chemical state and gas-sensing properties were investigated.The results show that the vulcanization effect of vulcanization at 400°C for 1.5 h in a negative pressure environment is the best upon the molar amount of thiourea is 15 times for WO₃.However,the gas-sensing element prepared based on this has not been significantly optimized.2.The preparation of Ru-modified WO₃nanowires,and the investigation of ethanol sensing.The modification of Ru on the surface of nanowires is realized by ultraviolet irradiating to reduce noble metal ions,and the gas-sensing properties of the material to ethanol are improved.The results show that the sensing device based on 4at%Ru modification can achieve the best ethanol sensing performance at a lower working temperature（200℃）,the response value for 100 ppm ethanol is improved by47 times,up to 120,and the detection limit reached 221 ppb.Comprehensive characterization results of TEM,XPS,we explain the improvement of ethanol sensing and performance3.Ru modulates Pt/WO₃nanowires and realize the preparation of near-room temperature high-performance hydrogen sensing materials.Utilizing the catalytic characteristics of Pt for hydrogen,reducing noble metal ions by ultraviolet irradiation,which was modified on the surface of WO₃nanowire material to improve the hydrogen sensing properties of the material.The results show the feasibility of Pt modification,unfortunately,the resistance of sensors is unstable when exposed to hydrogen atmosphere.Combining the previous work and the synergistic effect between multi-metals,we found that the catalytic activity of Pt was regulated by Ru,and realized the high-efficiency hydrogen-sensitive materials at near room temperature（70°C）（The response value of the best sensing material for 1 ppm hydrogen was improved by 742 times,up to 1010,and the detection limit was as low as 0.252 ppb）.Based on the results of XPS,semi-in situ Raman characterization and HER,we demonstrate the functionalization of the surface of double noble metal modification in the material and the sensing mechanism of materials for hydrogen.