Preparation Of MoO₃-based Two-dimensional Nanomaterials And Study Of Their Diisopropylamine Gas Sensing Propertie

Diisopropylamine（DIPA）is a kind of organic solvent with amine flavour,which has been widely used in pesticide,rubber and pharmaceutical industries.However,the US Occupational Safety and Health Administration has identified DIPA as a hazardous contaminant.Therefore,it is important to develop a portable DIPA sensor with high sensitivity,low detection limit,and stability for the safety of human production and life.MoO₃ is an n-type semiconductor with a wide band and unique layer structure,which has been extensively studied in the field of gas sensing,but the detection of DIPA has been less well reported and suffers from certain deficiencies.In this paper,MoO₃ porous nanosheets,CuMoO4/MoO₃ nanoplates and CoMoO4/MoO₃ nanosheets were synthesized and investigated for the detection of DIPA.This paper covers three main parts of the research:（1）The MoO₃ porous nanosheets were synthesized by a solvothermal method using molybdenum powder as the molybdenum source and ethanol as the solvent.After assembling the different calcined temperature products into sensors,it was found that the products after calcined at 500℃ presented better performance for DIPA at 217℃:The response value for 10 ppm DIPA is 30.4,and the minimum detection limit is 10 ppb.The mechanism of MoO₃ sensitivity to DIPA was also explored by XPS,GC-MS and comparative tests.（2）A solvothermal method was used to synthesize CuMoO4/MoO₃ nanoplate composites with different composite molar ratios using molybdenum acetylacetonate oxide as the molybdenum source,copper nitrate trihydrate as the copper source and acetic acid and water as the solvent.The molar ratio of 7:3 for the CuMoO4/MoO₃ sensor was 83.1 at 170℃ for 10 ppm DIPA.Not only has it achieved a reduction in the operating temperature of the sensor,but it has also succeeded in increasing the response value for DIPA.The reason for the improved performance of the composite was explored by UV-Vis diffuse reflection and XPS.（3）Using molybdenum powder as the molybdenum source,cobalt acetate tetrahydrate as the cobalt source and ethanol as the solvent,CoMoO4/MoO₃ nanosheet composites with different composite molar ratios were synthesized by the solvothermal method.When the molar ratio was 5%,the composite was produced with a response value of 87.6 for 10 ppm DIPA at 170℃,the response time was only 5.3 s,and the minimum detection limit was reduced to 5 ppb.In addition,UV-vis diffuse reflectance and XPS were used to investigate the causes of p-n heterojunction formation and performance enhancement.