Nanostructured WO₃-based Materials Prepared By Gas-liquid Interfacial Method And Their Gas Sensing Performance Research

Tungsten trioxide?WO₃?has a wide range of applications in gas detection and photocatalysis fields,as an important metal oxide semiconductor nanomaterial.However,single structure of WO₃ can not satisfy the requirements of gas sensor and photocatalytic performance.In order to adjust and control the gas-sensing and catalytic properties,WO₃-based nanomaterials are prepared.In this paper,WO₃-based nanomaterials are synthesized using a facile microwave-assisted gas-liquid interfacial method.Meanwhile,the properties of WO₃-based nanomaterials and the effects of tungsten sources are studied through two routes of alkalinity and acidity,respectively.The results of the study are as following:When WO₃-based nanomaterials are prepared by alkaline route,the all nanoparticles of WO₃-based are uniform size.The working temperature of pure WO₃ gas sensor is high,which shows good gas sensitive performance for H₂S and triethylamine,and the response and recovery rates are quick.The working temperature of WO₃/rGO gas sensor is significantly reduced compared with that of pure WO₃ by compositing WO₃ with rGO.The grain size of WO₃/rGO nanomaterials is reduced by adding different inorganic salt ions(Na⁺,K⁺,Mg²⁺,Al³⁺),and WO₃/rGO gas sensor has different gas sensitive performances for different test gases.In order to further improve the gas sensitivity of WO₃ nanomaterials,it is used to dopt WO₃/rGO with noble metal Ag.Ag-doped Ag/WO₃/rGO gas sensor has significantly better gas response than WO₃/rGO.Under UV irradiation,the gas response of Ag/WO₃/rGO is obvious enhanced compared with the no UV irradiation.The best working temperature is reduced,and the response of 100 ppm H₂S is increased from 204.5 to 685.8.The response and recovery rates are significantly improved.The morphology of WO₃-based nanomaterials obtained by different tungsten sources is significantly different.When WO₃-based nanomaterials are prepared by acidic route,the morphology of the nanomaterials is multistage structure of ball type and flower shape due to the different from the viscosity of solvent.When the volume ratio of water and ethylene glycol is 1:4,the 3D flower structure WO₃ nanomaterials are prepared.At room temperature,the 3D flower structure WO₃ gas sensor shows good gas sensitivity for triethylamine,and the gas response is 180.7.The response and recovery rates are quick,and it has long-term stability.At 90oC,this gas sensor exhibites good response for 10 ppm oxidized gas of NO₂.The gas sensitivity of pure WO₃ gas sensor prepared by acidic conditions is better than that of alkaline conditions.When WO₃ and rGO are composited,WO₃/rGO gas sensor shows good selectivity and gas sensitivity for the new gas ammonia and aniline.In addition to the study of gas-sensitive properties,the photocatalytic performances of WO₃-based nanomaterials prepared under acidic conditions are studied.The results shows that WO₃-based nanomaterials show a certain photocatalytic performance,but obviously weaker than their adsorption capacity.When the photocatalytic ability and adsorption capacity are simultaneous,the methylene blue?MB?organic dye can be effectively degraded in 2h.