Synthesis And Gas-sensing Properties Of One Dimensional MoO₃ Nanomaterials And Heterojunctions

The gas sensor can detect toxic,harmful,flammable and explosive gases,so they are widely used in household gas,industrial and mining enterprises of production safety and other fields.Due to the metal oxide semiconductor possess many advantage,for example low cost,high sensitivity,good stability and easy to carry,has gradually replaced solution.MoO₃ has a large specific surface area,electrons along the axis of transmission and a large number of active sites,so become a hot spot in recent years.However,there are some issue need to solved for single MoO₃,such as high working temperature and low selectivity.In this paper,the sensing properties of gas sensors based on MoO₃ were improved by the combined with other metal oxides and precious metals.The main work of this paper is as follows :?1?MoO₃ nanobelts were synthesized by the hydrothermal method.By the observe the SEM figure of MoO₃ of different hydrothermal conditions,we determine the optimum hydrothermal conditions for the preparation of MoO₃ nanobelts were170 ? and 45 h.The sensor element was prepared by using the obtained MoO₃ nanobelts.The WS-30 A gas sensing test system was used for gas sensing test and determined its optimum working temperature at 280 ?.?2?CoMoO₄/MoO₃ P-N nanocomposite and In₂O₃/MoO₃ N-N nanocomposites were synthesized by a simple wet chemical method.The microstructures of two different heterostructure composites were characterized and analyzed.The results of gas sensitivity test showed that the gas sensing properties of the two composites were improved compared with pure MoO₃,and the mechanism of the two composites was analyzed and discussed.?3?The introduction of precious metals to prepare Au @ MoO₃ nanocomposites.The material showed enhanced response to trimethylamine.Compared with the pure MoO₃,the sensitivity of the material was enhanced by 6 times.The enhanced gas sensing performance is explained by the energy band of the two material and the catalytic action of the noble metal.?4?rGO/MoO₃/Au ternary nanocomposites were fabricated by the hydrothermalmethod.The sensor prepared by this material was tested for gas-sensing performance to determine the optimum working temperature of the sensor at 160 ?.The sensitivity,selectivity and stability of the sensor at the optimum operating temperature were studied.The results showed that the sensitivity of the ternary composite material for 10 ppm trimethylamine up to 70.The sensor exhibits excellent anti-interference ability in the complex gas environment with various gases.?5?SnO₂ nanotubes were prepared by using MoO₃ as a matrix.The results show that the thickness of SnO₂ nanotube wall is about 30 nm.Due to the large specific surface area of SnO₂ nanotubes,so the contact area between the surface and the gas is increased.The results show that SnO₂ nanotubes have good gas sensing properties for NH3 at room temperature.