The Self-Assembly Behavior And The Performance Of Functional Material

With the development of nanoscience and nanotechnology, the functional materials with special property can be prepared to meet a certain need. Based on the needed performance, the functional composite can also be designed to form a special structure through arranging the atoms, which make the new product have superior property. Therefore, the attempts have been made to synthesize different samples as the raw material for the further study. Meanwhile, via a assemblly technique, the hybrids are shaped with particular morphology and optical, electronic, photoelectric and magnetic property.First of all, we have successfully synthesize different material including:0-D Quantum dots (QDs),1-D titanate nanowhiskers(nanorods), the quasi 2-D nanosheet and nanofilm. At the same time, the opening and modifying of muti-walled carbon nanotubes (MWCNTs) also have been investigated. The details are given as follows:(1) The ZnO QDs have been fabricated trough a sol-gel method, which is about 4nm in size and can be individually dispersed in the solution. (2) Different opening and modifying methods of MWCNTs are studied and compared in this paper, for example the fluxed HNO3 or O3 under ultrasoundic condition. The influence of temperature, concentration and holding time on the BET value of MWCNTs is studied in details. At the same time,1M HNO3 or 1M CF3COOH is elected as reactant medium and catalysis to prompt the reaction with O3 and MWCNT. Compared with the traditional ccHNO3, O3 can not only open the caps of MWCNT, but also cut the MWCNT from the sidewall at room temperature. The surface structure of MWCNTs treated by different processes is analyzed by FT-IR. The texture of MWNTs is tested by BET and confirmed by TEM. UV-Vis is employed to detect the solubility of modified MWCNT in ionic solution (IL), and the enhanced conductivity of IL has been tested. (3)Stating from H2Ti03 and K2CO3 with different mole ratio, potassium hexatitanate(K2Ti6O13) nanowhiskers and potassium teteratitanate (K2Ti4O9) nanorods are directly synthesized by one-pot solid state reaction. The novel phase transformation and structure changes behavior are investigated under a facile different hydrothermal condition with acidic or basic system in a series of steps. Specially, the photocatalytic activity of nano-structured TiO2 products are examined by the decomposition of the indigo carmine solution. The results indicate the as-synthesized nanopaticles of anatase TiO2 shows good photocatalytic property under the irradiation of visible light, compared with commercial photocatalyzer of P25. (4) A conventional process to prepare the nanosheet include the following steps, the solid-state reaction, then protonic procedure for several days with daily refreshed acid and the exfoliation by tetrabutylammonium hydroxide (TBAOH) for 10 days. Via the above process, the TiO2 nanosheets (TNS), MnO2 nanosheet (MNS) and TiTaO5 nanosheets can also be synthesized. However, on the basis of the above analysis, the traditional whole process to obtain the nanosheets has some drawbacks, such as complication, uncontrollability, time cost. An easier, lower cost and environment-friendly way was urgently required to produce the nanosheets. Therefore, a facile, innovative mechanical cleavage process with strong shear have been considered to exfoliate the layered structures. Through the novel mechanical cleavage technology, Ti5NbO14, TiNbO5 and TiTaO5 nansosheets solution with good quality and higher concentration have been formed. A series of methods with XRD, SEM, AFM, TEM, PL depict the super thin thickness of nanosheet and the optical property. At the same time, the negative properties of the nanosheets have been confirmed by Zeta potential, and the nanosheet solution also showes good Tyndall light scattering phenomena.Secondly, we have investigate the self-assembly behavior and the related performance of modified MWCNT.The Fe3O4@MWCNT composite have been fabricated by one-step procedure, which have good soft magnetic property and can immediately move to the added magnet.In order to obtain the stable MWCNT heterostucture, the functional MWCNT can be obtained by covalent reaction has become a trend. In this paper, we report the synthesis of ZnO QDs and the functionalized MWCNTs (f-MWCNTs) hybrid through Zn-S covalent bridge link to enhance the stability and reliability of heterojunction structure even under rough condition. The TEM, SEM, FT-IR, EDS UV-Vis, and PL results give us a lot of information such as, the morphology, optical, electric and photoelectric conversion property. It has been found the composite is an semiconductor material, which shows the negative temperature coefficient resistance, the PL quenching phenomena and the red-shifted UV-Vis absorption. At the same time, the dye-sensized solar cells (DSSCs) based on the composite of multi-walled carbon nanotubes (MWCNTs) anchoring with two different semiconductor, namely titannate dioxide and zinc oxide are studied. The photocurrent and photovoltage output can be easily detected. An increase of the open-circuit voltage (Voc) and the short-circuit photocurrent (Isc) can be explained by the increased surface area of the film, the enhancement of transformation ratio of electron with the help of MWCNT.Lastly, we have investigated the self-assembly behavior and the related performance of different nanosheets.(1) The individual or complexed nanosheet films are designed by LBL technique, and UV-vis absorption spectroscopy was used to monitor the consecutive buildup of the film, and the complexed film can be facile to absorb the visible light. It can be deduced that the as-prepared nanosheets have dispersed well and rather stable in the TBAOH system. In addition, the adsorption of the film with Li+ well confirmes that the film is better electrode material.(2)Lamellar aggregates with high efficient green and red emission of the TiTaO5 nanosheets dopped with rare earth ions of Tb3+ or Eu3+ have been fabricated by flocculation of colloidal solution with electrostatic self-assembly deposition(ESD) technique. The as-obtained composites are analyzed by a range of methods including XRD, TEM, EDS, UV-Vis, PL to discuss the structure, morphology, the energy transfer and the photoluminescent property. The results indicate that the re-stacking of the nanosheets could form a uniform layered structure, which was assembly formed by electrostatic interaction between the negatively charged nanosheets and positively charged RE ions. When the HCl is taken part of rare earth ions, the nanosheet solution also have been re-stacked to form the wool-like precipitation. By analysis the BET vale and the degradation of dye solution as photocatalyzer, the experiment detect they have the bigger specific surface area and exhibit the better photocatalysis property.(3)Via an electrophoretic deposition method (EPD) technology, When a piece of copper is considered as the counter electrode, the transparent and smooth film consisted of naosheets can be casted on the ITO. The as-prepared film can be widely applied in Li battery. In addition, when the ITO was used under the same condition, the beautiful "nanorose" was loaded onto the ITO. In a word, these works might open a new door for the design of the electrode, which could be modified with this new nanosized sheet.