Controllable Preparation And Applications Properties Of Nano Molybdenum Disulfide

In recent years,two-dimensional materials represented by graphene have attracted extensive attention because of their unique morphology,structure and supeiror application performance.As a typical two-dimensional transition metal sulfide,MoS₂ exhibits great application prospects in many fields due to its low preparation cost,good stability and excellent chemical properties.However,the morphology of MoS₂nanoparticles is relatively single and difficult to control,and the base surface reaction activity is low,which limits its application.Therefore,it is important to prepare MoS₂ nanoparticles with controllable morphology,abundant surface active sites and high reaction activity.According to this view,this thesis synthesized nitrogen doped MoS₂ nanoflowers by coprecipitation combined with solvothermal method and explored the influences of different process conditions on the product.Furthermore,the application performance of Cr（Ⅵ）removal and glyphosate adsorption was studied.The main research contents and results are as follows:（1）Nitrogen doped MoS₂ nanoflowers were fabricated by coprecipitation combined with solvothermal method.In this process,（NH₄）₆Mo₇O₂₄·4H₂O,Na₂S·9H₂O and N,N-dimethylformamide were used as the molybdenum sources,sulfur sources and solvent.The effects of different conditions on the products were studied,and the optimal process conditions were obtaind as followed.The reaction time was 12 h,the reaction temperature was 200℃,and the addition amout of reductant hydrazine was 10 m L.Under the optimal conditions,nitrogen doped MoS₂nanoflowers with particle sizes of 40 nm,150 nm and 400 nm were prepared by changing the type of reductant.The products have flower-like structures with regular morphology,uniform particle size and high crystallinity.Nitrogen was doped into MoS₂ in the form of covalent bond,and the doping amount was about 2.6 at%.Nitrogen doped MoS₂nanoflowers possess widened interlayer spacings and abundant sulfur vacancy defects.The optimal N-MoS₂ NFs-40 nm was 1T-2H mixed phase with the most sulfur vacancy defects and the highest specific surface area(125.6 m²·g^-1).（2）The application performance of MoS₂ nanoflowers on the removal of Cr（Ⅵ）was explored.The effects of different parameters on Cr（Ⅵ）removal were studied.The results showed that the Cr（Ⅵ）removal rate increased with the decline of p H value and the temperature rising.Under the condition of 298 K and p H=2,the Cr（Ⅵ）removal rate of N-MoS₂ NFs-40 nm was highest,which can reach 100%in 15 minutes and the maximum adsorption capacity was 787.4 mg·g^-1.Furthermore,the Cr（Ⅵ）removal rate can still remain above 98%when a variety of competitive ions coexist.（3）The application performance of MoS₂ nanoflowers on the removal of glyphosate was explored.The effects of different conditions on glyphosate removal were studied and the results showed that the adsorption process of glyphosate conforms to the pseudo-second-order kinetic model and Langmuir model.The adsorption capacity of glyphosate increased with the adsorption temperature and time rising.Under the condition of 298 K and p H=2,the glyphosate removal rate of N-MoS₂ NFs-40 nm was highest,which can reach 95.6%in 10 min and the maximum adsorption capacity was 602.4 mg·g^-1.After three cycles of regeneration,the removal rate of glyphosate can still be maintained at more than 75%.