【作者】 刘辉；

【导师】 李家俊；

【作者基本信息】 天津大学 ， 材料学， 2012， 博士

【摘要】 获得结构均匀可控、合成简单、性能良好的纳米材料一直是材料研究的重要内容，探索合成纳米材料的新方法及新概念具有重要的理论意义。本论文将高能激光与常规的化学反应结合，创造出了新颖的反应条件，得到一系列不同形貌与结构的新型纳米结构，深入研究了纳米结构的合成机理，揭示了激光对化学反应的影响规律。采用激光烧蚀法合成了活泼金属纳米颗粒。研究了不同激光烧蚀工艺对纳米材料分散性与均匀性的影响，通过控制载气流量及纳米颗粒飞行距离得到了均匀分散的产物。采用激光制备的活泼金属纳米颗粒进行伽伐尼置换反应，得到了应用前景良好的多孔金纳米球。利用激光合成的Zn纳米颗粒作为起始原料，研究了在Zn/Cu_<sup>2+体系中伽伐尼置换反应的机制。发现界面氧化层对活泼金属的伽伐尼置换反应具有决定性的影响，在没有界面层的情况下得到了大量的铜纳米枝晶，在有界面层时得到了大量的粒径均匀的单分散的铜纳米颗粒。提出了纳米尺度溶剂热反应的概念。利用激光辐照溶液中的铜纳米颗粒，使之加热溶剂，诱导溶剂热反应，制备金属半导体异质结。研究了激光能量、激光作用时间、反应物对产物的影响。设计了CuCl水解工艺，获得均匀可控的Cu₂O空心纳米立方体。发现CuCl微粉在低pH值的水溶液中首先形成均匀的CuCl纳米立方体。该立方体作为牺牲模板在较高的pH值下通过水解形成Cu₂O空心立方体，本工作首次证明了水解是一种简单高效的制备空心纳米结构的新方法。此外，系统研究了CuCl在不同pH值水溶液中的反应机理，通过控制pH值分别合成尺寸均匀的铜纳米颗粒、氧化亚铜空心立方体及氧化亚铜实心立方体。研究了激光调控CuCl的水解反应。将CuCl的水解反应置于激光下，利用激光成功地改变了化学反应进程，在酸性条件下得到了氧化亚铜立方体。研究了激光波长、激光能量、激光作用时间对产物形貌的影响，为利用激光光化学法合成纳米材料做了有益的尝试。更多还原

【Abstract】 Fabrication of nanomaterials with uniform and controllable structure, simplesynthesis process, and good performance is an important topic in materials field, andthe explorations of new methods and new concepts are critical to the synthesis ofmaterials. In this thesis, high energy laser is combined with common chemicalreactions to generate extreme synthesis conditions, resultantly, a series of novelnanostructures are obtained. The formation mechanisms of novel nanostructures arecomprehensively investigated, and the principle of laser effect is discovered.Laser ablation method is adopted to synthesize active metal nanoparticles. Theparameters of laser ablation are varied to determine their influence on the dispersionand uniformity of nanoparticles. It is found that the gas flux and flying distance ofnanoparticles are the key factors on preparing uniform and disperse product.Furthermore, active metal nanoparticles prepared under different laser ablationconditions are used for the galvanic replacement reaction, resulting in porous hollowAu nanospheres which are considered promising for bio-application.The laser synthesized Zn nanoparticles are employed as a starting material for thegalvanic replacement reaction with Cu_<sup>2+ions, and surface oxide layer of Znnanoparticles shows a remarkable impact on the reaction and products. Coppernano-dendrites were obtained in absence of the oxide layer, a large number of uniformsize monodispersed copper nanoparticles were fabricated without the oxide layer.The concept of nanoscale solvothermal reaction is proposed. The laser irradiationis introduced to heat Cu nanoparticles, which act as the heat source to induce thesolvothermal reaction and then the formation of the metal-semiconductorheterojunctions. The laser energy, irradiation time, precursors are varied to makecontrol experiments.A hydrolyzation process is proposed to synthesize uniform and controllable Cu₂Ohollow nanocubes. The formation mechanism of Cu₂O hollow nanocubes is discussed.It is found that CuCl micropowder first decomposes and then precipitates to give riseto uniform CuCl nanocubes which act as sacrificial templates to produce Cu₂O hollownanocubes by hydrolyzation. This work demonstrates for the first time thathydrolyzation is an effective way to produce hollow nanocubes. The influence of the pH value on the reaction of CuCl in aqueous solution was studied systematically,copper nanoparticles and hollow cuprous oxide nanocubes were obtained at differentpH value.The hydrolyzation of CuCl is conducted under the laser ablation, and thechemical reaction is modified by the laser energy, and Cu₂O nanocubes are obtainedunder acidic conditions, which is obviously different from the case without laserenergy. The influence of laser wavelength, laser energy and laser irradiation time onthe morphology of products is investigated, which is a meaningful attempt on thematerials synthesis by laser chemistry.更多还原