Synthesis And Gas Sensing Properties Of In2_O3 Nanotubes

Indium oxide（3.55³.75 eV）, a direct wide band gap n-type semiconductor has attracted considerable attention due to its significant optical and electrical properties. These properties make In₂O₃ highly promising in many fields, such as solar cells, field-effect transistors, photodetectors, gas sensors and photocatalysts. In this paper, co-electrospun method was used to synthesize In₂O₃ nanotubes materials and their sensing properties were arried out indetail. The main contents are as follows:（1） Fabrication of porous SnO2/In₂O₃ nanotubes by co-electrospun with enhanced gas sensing propertyPorous In₂O₃ nanofibers（about 50¹00 nm in diameter, several micrometers in length） were prepared through the co-electrospun method using indium nitrate as inorganic source and polyvinylpyrrolidone as thickener agent. By adjusting the amount of indium nitrate and PVP, SnO2/In₂O₃ nanotubes were obtained. All the samples were composed of SnO2/In₂O₃ nanoparticles（5 to 10 nm）, which lead to high specific surface area（56 m2/g） and these SnO2/In₂O₃ hetero-nanotubes exhibit the high response（400 at 500 ppm）, low detection limit（down to 250 ppb）, fast response（60 s）/recovery（97 s）, and well retentivity（94.68 % for 30 day） and selectivity toward formaldehyde.（2） Synthesis of Zn doped In₂O₃ nanotubes by co-electrospun for formaldehyde sensingZn doped In₂O₃ nanotubes about 100 nm in diameter are synthesized via co-electrospun method using zinc chloride and indium nitrate as inorganic sources. SEM, TEM, and XRD were adopted to reveal the nanotubes and porous structure of these zinc oxide/indium oxide nanocomposites. These porous Zn doped In₂O₃ were configured as excellent performance on formaldehyde sensing, showing high sensitivity（S=505 at 500 ppm）, low detection limit（S=5.54 at 0.25 ppm）, excellent recycle ability（87.63 % for 30 day） and selectivity toward formaldehyde. And the reponce behavior can be adjusted by vaying the amount of Zn doping.（3） The use of co-electrospinning method to prepare Ag/In₂O₃ nanotubes for formaldehyde responceSilver/indium oxide nanotubes were synthesized by co-electrospinning method, characterized by SEM, TEM, XRD, proving the successful synthesis of the Ag/In₂O₃ nanotubes. All of the Ag doped sensors showed better sensing performance in sensitivity（S=1016 at 500 ppm）, selectivity, optimum operating temperature（400 °C）, fast response/recovery（50 ppm, 174/12 s） and well recycle ability（94.12 % for 30 day） in formaldehyde concentration range of 0.25⁵00 ppm. The high sensor performance demonstrate that the Ag/In₂O₃ sensors are very promising devices for formaldehyde detection in the future.