On The Synthesis Of Nanoscale Gas Sensing Materials With Heterojunction And Their Enhanced Gas Sensing Properties

The environmental harmful gases such as NO2 and triethylamine always endanger our environment and human's health,and metal oxide semiconductor based sensors have the advantages of low cost,good stability and the ability of real-time detection.But single metal oxide gas sensing materials can't meet the requirement of harmful gas detection.Many reports have demonstrated that the designation of micro/nano structure and the formation of heterojunction could significantly improve the gas sensing properties of materials.In this paper,metal oxide gas sensing materials with micro/nano structure and heterojunction were synthesized through different method and applied for detection of harmful gas NO2 and triethylamine.The main contents are listed as follows:1.One dimensional ZnO-SnO2 hollow nanofibers were synthesized via a one-step electrospinning method and annealing treatment.The morphology and structure of the nanofibers have been characterized by various analysis methods,and the sensing properties to 0.5-5 ppm NO2 have also been examined.The results reveal that the SnZn20 sample(20atm%Zn composite)not only exhibits the high response of 46,but also exhibits rapid response,excellent selectivity and stability toward 1ppm NO2 at low operating temperature of 90 °C.So,herein synthesized composite is a promising sensing material for detection of NO2.The enhancing sensing mechanism is discussed in detail,which is attributed to the unique one-dimensional hollow nanostructures and the heterojunctions formed at interface between both metal oxides due to the rebuilding of Fermi level.2.The assembled NiO nanosheets hollow spheres have been synthesized by a facile precipitation method using SiO2 spheres as hard template,which have large specific surface area(224 ma/g)and unique morphology.The sensing properties for TEA gas were improved by Fe element doping and the combination with ?-Fe2O3.The test result reveals the improvement of sensing properties toward TEA for two approaches.The sensing mechanism of?-Fe2O3-NiO composite is discussed in detail,which is attributed to the high specific surface of hierarchical structures and the heterojunction formation at interface both metal oxides due to their difference of Fermi level,leading to the variation of resistance.