| Information and energy is currently a major research area countries,because they relate to the socio-economic development and national security.In recent years,the most important subjects of intensively current research in chemistry,physics,biology,materials science,engineering and techenology have focused on designing and constructing novel functional nanomaterials,not only because of their intriguing variety of architectures but also owing to their potential applications as functional materials.Nanoclusters and nano semiconductor materials have been caused widespread concern and research worldwide,because of its unique nature of small-size effect,surface effect,and macroscopic quantum tunneling effect and other effects.Based on the above research needs of the significance and urgency.This paper from the chemical synthesis of nanomaterials,we study and explored the preparation,characterization,properties and applications of three types of functional nanomaterials.One is a transition metal clusters,developed a chemical synthesis of a nickel-metal clusters method,and successfully synthesized different sizes of nickel clusters and studied its optical properties of electromagnetic and assembly;Another feature of semiconductor optoelectronic nanocrystals,mainly to study the controlled synthesis and properties of Sb2S3,PbxSbySz system nanomaterials;the third category is nanocrystalline functional modification,mainly to study the fluorescence properties and exciton coupling of nanocrystalline surface complexes,and applied to the preparation of light-emitting devices and cellular imaging.The main structure and the results of this research are summarized as follows:In the introduction,we introduces the basic concepts of nanomaterials and special electrical,optical,mechanical,thermal,magnetic and other properties;describes the synthesis of nanomaterials and applications in biology,medicine,catalysis,national defense science and technology.In the second chapter,Thiolate-protected nickel clusters,Ni27（SC2H4Ph）i9,Ni29（SC2H4Ph）20 ,Ni39（SC2H4Ph）24 and Ni41（SC2H4Ph）25 were synthesized via a wet chemical reduction method.The structure,composition,morphology and clusters assembly structure of the nanoclusters were characterized by MALDI-TOF mass spectrometry,X-ray photoelectron spectroscopy（XPS）,X-ray powder diffraction（XRD）,UV-visible absorption spectrum（UV-Vis）,VECTOR 22 infrared spectroscopy（FTIR）,field-emission scanning electron microscope（SEM）,high-power transmission electron microscopy（TEM）respectively.The results showed that the average diameter of the Ni nanoclusters about 2.0 nm with good dispersion in non-polar solvents（e.g.cyclohexane）,and molecule-like transition feature are observed in Ni39（SC2H4Ph）24 and Ni41（SC2H4Ph）25 clusters.Ni nanoclusters had a face-centered cubic structure.Ni nanoclusters exhibit ferromagnetism（saturation magnetization 0.088 emu/g）and larger coercivity（coercivity 345 Oe）at room temperature by using a superconducting quantum interference device（SQUID-VSM）.In the third chapter,we tried a variety of methods and ways to synthesis Sb2S3 nanocrystal,and the exploratory research has been launched for the synthesis,controlled micro-structure and performance of Sb2S3 nanocrystal.In the study,the thermal decomposition method employs organometallic compounds containing metals and chalcogenides as the precursors,which decompose at low temperature in organic solvent.Using SbCl3,Sb（OAc）3,triphenyl antimony as the antimony source,and trying to use elemental S,thioacetamide,bis（trimethylsilyl）sulfide,dodecyl mercaptan as sulfur source,and ODE,Oleic acid,oleylamine,liquid paraffin,TOP as solvent.The different morphologies SbZS3 nanoparticles by varying the ratio of Sb and S,changing the solvent,reaction temperature,etc..The resulting products were then characterized by XRD,SEM,TEM,UV-visible spectroscopy,nanocrystals solar cell efficiency tests.In the fourth chapter,PbxSbySz semiconductor nanocrystals were synthesized by a solvothermal method under N2 protection,using oleylamine（OY）and oleic acid（OA）as a stabilizer,and lead oleate and antimony oleate as a precursor.The samples were characterized by XRD,UV-Vis,TEM respectively.The XRD indicates that PbxSbySz semiconductor nanocrystals were changed from the original PbS cubic structure to wurtzite hexagonal with an increase in the molar ratio of Sb.TEM results showed that nanocrystals dispersed better,the average sizes of the nanocrystals were in the range of 5-7nm.And the semiconductors band gaps were found between 1.7eV-2.1eV by UV-Vis,which are very close to the maximum absorption of solar energy.In the fifth chapter,using the ligand exchange approach,strong fluorescence originating from surface coordination complexes was successfully achieved from NCs of various components and structures:ranging from insulator,semiconductor to metal NCs,with either pure phase,doped or core/shell structures.For example 8-hydroxyquinoline modified ZnS nanocrystals surface complexes showed strong fluorescence（quantum yield:12.2-33.0%）,and TTA-coordinated Eu,Nd,Yb or Er doped NCs result in more than 50 times higher intensity of the lanthanide-based photoluminescence than that of the as synthesized NCs before TTA coordination.The photoluminescence can be reversibly tuned across the visible and infrared spectrum,and even allow multi-color emission from single NCs.A light emitting device was fabricated and a new in cell imaging method was performed to demonstrate the power of this technology for emerging applications.In the sixth chapter,8-hydroxyquinoline modified ZnS nanocrystals were made as a model to study the exciton coupling phenomena of nanocrystalline surface complexes.By controlling the concentration of surface complexes successfully regulated the exciton coupling effect,and realized the control of absorption and fluorescence spectrum.This strategy is expected to be used in the quantum dot photovoltaic cells and photocatalysis. |
