The Influence Of Morphology And Gas Sensing Properties Of α-Fe₂O₃ Nanostructures Through Zn Doped And Precursor Solvent

In recently,more and more toxic gases are emitted into the atmosphere by producing and burning fossil fuels,vehicular exhaust and biological metabolism,etc.Therefore,the harmful gas of effective monitoring is particularly important.Producing and developing the gas sensor is one of the important ways of solve environmental problems.In recent years,Fe2O3 is a key gas-sensing material in laboratories,and it is also the main research object in this paper.Among various metal oxide semiconductors,iron oxide(α-Fe2O3)with a wide bang gap(2.1 eV)and large exciton binding energy(60 meV)is considered as one of the most stable gas sensing materials.According to the current research status,the synthesis of iron oxide nanomaterials technology has become increasingly mature,such as one-dimensional nanowires,nanotubes;two-dimensional nano-layers;three-dimensional nanospheres,nanocubes and nanoflowers.However,the impact of the system on the morphology and gas-sensing properties of the reaction environment is still lacking.Therefore,we can further optimize its morphological changes by changing its reaction parameters,such as changing the reaction solvent,doping,recombination and surface modification.Three-dimensional layered α-Fe2O3 nanomaterials have several advantages such as high specific surface area,open structure feature,less agglomerated configuration and highly surface energy,which are effective to enhance the gas sensing performance.This paper is based on three-dimensional nanomaterials,controlling the water-ethanol solvent ratio and metal ion doping,The functional nanomaterials with different morphologies were prepared and their gas sensitivity characteristics were studied and analyzed.Mainly works and results are as following:1.3D leaf-like Alpha-iron oxide(α-Fe2O3)nanostructure and other nanomorphologies were fabricated by adding different ethanol content in ethanol-water mixed solvent under a simple solvothermal route.The structures and morphologies of nanostructures were characterized by X-ray diffraction(XRD),field emission electron scanning microscopy(FESEM)and transmission electron microscopy(TEM).Their morphologies and gas-sensing properties were mainly studied.The sensor synthesized in 80 vol%ethanol-water as the solvent exhibited lower operating temperature(260℃),higher response and shorter Response/recovery time(about 8 s and 9 s).The results indicated that 3D leaf-like iron oxide(α-Fe2O3)nanostructure was a potential candidate for fabricating effective acetone sensor.2.Quasi-cubic Zn-doped α-Fe2O3 nanostructures had been synthesized via a one-pot hydrothermal route follow by an annealing treatment.The structure and morphology of nanoparticles were characterized by various techniques.The as-prepared products combined the advantages of unique structure,well crystallinity and high facets energy.Zn2+ used as an induced agent to obtain Zn-doped α-Fe2O3 nanostructures which lead to shape and grain size were changed.The acetone gas-sensing properties of the Zn-doped α-Fe2O3 nanostructures as sensing materials were measured,which presented good selectivity and high response compared with pure α-Fe2O3 nanoparticles.Moreover,the fast response and recovery characteristics was exhibited of the Zn-doped sample at a low concentration.finally,the possible growth mechanism of α-Fe2O3 nanostructures was also discussed in detail.