The Electrical Performance Improvements Of Semiconducting Gas Sensor Based On Noble Metal Modification

With the rapid development of technology,we human beings are enjoying all kinds of conveniences from the innovation of chemical industry and new materials.Meanwhile,various toxic and harmful gases become a great threaten to our safety and physical health.Therefore,monitoring those toxic and harmful gases(such as benzene,formaldehyde,carbon monoxide and methane)in the environment effectively can not only ensure the safety of industrial activity,but also help us to foresee these potential threats around our living surroundings.Since the gas sensing capability of semiconductor metal oxides was demonstrated,gas sensors based on these semiconductor metal oxides materials have attracted wide attention from scientific point of view.And a series of gas sensors have been developed.Gas sensors,whose sensing part is made up of semiconductor metal oxides,have turned into a hotspot in the gas sensing field owing to its advantages of simple synthesis process,small volume and sensitive detection ability,etc.Since of the pure oxide semiconductor materials often possess a good crystallinity and few of defects,its sensing performances are poor.Researchers usually adopt the strategies of synthesis materials with different morphologies,in-situ doping and surface modification with noble metals to promote the gas sensing properties of oxide semiconducting materials.From the view of the structure and size of nanomaterials,in order to design gas sensors with high performances,hierarchical 3D Zn O materials,which considered to be a promising structure in sensing field,were fabricated by a facile solvothermal method.And the synthesized materials are modified with noble metals,which makes the gas sensitive properties of the materials improved,obviously.The research findings in this paper are as follows:(1)The small size nanoparticles often exhibited low gas sensing properties due to the poor diffusion process caused by their dense accumulation between each other.In order to overcome this shortcoming,hierarchical 3D porous Zn O microspheres made from tens of porous nanosheets,which thickness is about dozens of nm,were synthesized through a hydrothermal method.Ultra-small Au nanoparticles(1-2 nm)were successfully decorated on the surface of 3D porous Zn O microspheres through a facile,surfactant-free and green precipitation manner to enhance its acetylene sensing performance.Gas sensing measurements revealed that the Au-Zn O microspheres showed a remarkable improvement and reached the maximum response of 311.3 to 100 ppm acetylene,which was about 25 times higher than that of the pure one.(2)Ag nanoparticles were grown on the hierarchical porous Zn O microspheres using a green and facile precipitation method.It could be observed clearly that massive Ag nanoparticles with sizes of 50-80 nm were loaded on the interspaces and grown on the surface of the porous nanosheets.And their gas sensing performances were measured.The measurement showed that the sensor based on Ag-Zn O microspheres displayed an ultra-high response to triethylamine(TEA).Its response to 100 ppm TEA is 6043.(3)A novel hierarchical Zn O rose-like structural material was obtained assisted by PVPk30 with low viscosity.We investigated the morphological evolution of the samples which were traced with hydrothermal time.A gas sensor based on the hierarchical Zn O material modified with Au nanoparticles was fabricated.The gas sensing measurements showed that the sensor displayed superior BTX(benzene,toluene and xylene)sensing properties.a)The operating temperature was reduced from 302 ? to 206 ?.b)The responses of the sensor to 20 ppm benzene,toluene and xylene were 16.25 46.43 and 76.47,which were about 4.33,4.47 and 6.51 times higher than the pure sensor.3)The sensor also exhibited fast response/recovery property(5 s/50 s).