Synthesis, Gas-sensing And Adsorption Of MoS₂, MoO₃ And Co₃O₄ Nanosheets

Two-dimensional nano structures have large specific surface area and good dispersivity,which is good for applications in the area of gas sensing,photocatalytic degradation and adsorption.Among these 2wo-dimensional nano structure materials,MoS₂ has attracted much attentiont after graphene.It is a p-type semiconductor with Eg = 1.97 eV;MoO₃ is an important n-type semiconductor with steady chemical property,which is environmentally friendly with Eg = 2.9 eV;Co₃O₄ is a spinel structure p-type semiconductor,with Eg = 1.5 eV.It might be valuable topics to synthesize these nanosheets structure materials,to study the performance and mechanism,such as the gas sensing properties,photocatalytic degradation and adsorption properties for their applications.This dissertation mainly includes 3 parts:Firstly,MoS₂ spheres composed of nanosheet were synthsized using hydrothermal method.The effects of reactants ratio,reaction time,surfactant and reaction temperature on the morphology of the obtained samples were studied.MoS₂ nanosheet spheres have good gas sensing properties to dimethylamine?DMA?at the working temperature of 160?.The response to 1000 ppm DMA reaches 7.The photocatalytic degradation property of MoS₂ nanosheet spheres is not obvious,but adsorption property is exellent: the adsorption efficiency to 10 mg/L RhB is 96% within 500 min,while that of the commercial MoS₂ is only 44.3%;the adsorption efficiency to 10 mg/L MO is 96.6% within 700 min,while that of commercial MoS₂ is only 31.5%.These gas sensing property and excellent adsorption performance might be attributed mainly to the nanosheet sphere structures,which are not only benefit the charge transfer but also beneficial for the rapid diffusion.Secondly,MoO₃ nanosheets were prepared by sintering MoS₂ nanosheet spheres.The obtained MoO₃ nanosheets have good response to DMA and TMEDA at working temperature of 340?.The response to 1000 ppm DMA and TMEDA reaches 400 and 996,respectively.Same as MoS₂,photocatalytic degradation of Mo O₃ nanosheets is not obvious,but adsorption performance is very good: adsorption efficiency to 10 mg/L methylene blue is 96.1% within 90 min,adsorption efficiency to 10 mg/L methyl orange is 97.4% within 120 min.Thirdly,Co₃O₄ nanosheets were synthesized using hydrothermal method.During the synthesis procedure,influence of the static time and sintering temperature on sample morphology are studied.Results show that sample morphology is the best as being static two days and calcinated at 350?.Good selectivity,short response and recovery time is also observed in this sample.For samples calcinated at 350?,400? and 500?,responses to 100 ppm TMEDA are 12,10 and 4,respectively.In addition,to 10 mg/L CR,the adsorption efficiency of sample calcinated at 350? is 85% within 5 min,and 100% within 1 h.