Preparation And Physical Properties Of Two Dimensional Layered Materials Quantum Dots

Successful exfoliation of single atomic layer graphene nanosheet has inspired people to pay more attention to other van der Waals two-dimensional layered structure materials,including boron nitride(BN),transition metal dichalcogenides(TMDs)and black phosphorus(BP).The common feature of these 2D materials is that they have strong in-plane covalent bonds within each sheet but interact with each other via weak out-of-plane,van der Waals bonds.As another structure form of nanomaterials,quantum dots(QDs)will exhibit unique electronic and optical properties due to the quantum confinement and edge effects.To date,the main strategies to prepare 2D layered material QDs are "top-down" methods,including liquid phase ultrasonic,ion-intercalation etc.However,these strategies are usually limited by the harsh conditions,time consumption,complicated post-treatment process.In this paper,turbulence-assisted shear disintergration has been innovatively put forward to prepare BN QDs,WS2 QDs,MoS2 QDs and BP QDs,and this method has the advantages of simple,fast and efficient;meanwhile,we have also successfully synthesized carbon dots via hydrothermal method with celery as carbon source.Further,this paper has carried out preliminary biological diagnosis study and metal ion detection of 2D layered material QDs.My specific research content and research results are as follows:1.High-quality BN and WS2 QDs have been successfully prepared through turbulence-assisted shear disintergration.Bulk BN and WS2 are cracked in organic solvent by using high speed rotating blade,and QDs have been characterized by TEM,AFM,Raman,XPS,UV/Vis.As clearly shown in figure,QDs have good dispersion,uniformly particle distribution,highly ordered lattice fringes,indicating QDs are well-crystallized.Under the same experimental conditions,we have succeeded in preparation of carbon dots,MoS2 QDs,BP QDs,which has once been used to confirm the universality of this fantastic method.In addition,the vortex theory of fluid dynamics has been applied to interpret the result in this paper.2.Hela cells have been used to evaluate the inherent cytotoxicity of BN QDs and carbon dots through MTT,demonstrating QDs show excellent biocompatibility and low toxicity fluorescent phenomenon can be found via laser confocal fluorescence microscopy.Laser irradiation experiment of WS2 QDs solution shows that the WS2 QDs solution temperature was increased from 24.2 ℃ to 51.4 ℃ within 7.5 min,proving strong photo-thermal performance of WS2 QDs.3.High-quality carbon dots have been successfully synthesized via hydrothermal method with celery as carbon source.Celery and deionized water are put into the reaction kettle to obtain carbon dots at a certain time and temperature by filtering and centrifugating.TEM shows that carbon particles are distributed evenly;FI-IR shows that the surface of carbon dots contains rich oxygen containing functional groups,showing good solubility in water;PL shows that carbon dots has excellent fluorescence performance;PH and NaCl ion concentration shows that carbon dots have stable optical properties.For metal ion detection of carbon dots,different metal ions are applied to this paper on the same conditions.The carbon dots in our paper have the most sensitivity for the iron ion.