光化学还原反应可控制备银基和铜基纳米材料及其应用

发布时间：2018-04-10 02:01

  本文选题：光化学还原反应　切入点：纳米材料　出处：《苏州大学》2015年硕士论文

【摘要】：铜族(Au、Ag、Cu)纳米材料由于其独特的表面等离子共振(surface plasmon resonances,SPRs)而表现出优异的物理化学性质,尤其是光学性质。表面等离子体共振是一系列增强光谱技术,如是表面增强拉曼、荧光增强等的重要增强机理。利用表面等离子体共振增强光谱技术,科学家们已经实现了痕量检测,甚至是单分子检测的目的。此外,表面等离子体共振在光催化降解、红外热疗、生物标记等领域也具有极大的应用价值。通过调控纳米材料的组成、形貌、尺寸和纳米材料的空间维度等,可实现对纳米材料性质的调控。已报道的研究工作主要集中在金、银纳米材料上,对Ag2O纳米材料、铜基纳米材料的研究相对较少。目前,用来制备纳米材料的方法有很多,包括水热法、脉冲-激光沉积法、溶胶-凝胶法、电化学沉积法、化学气相沉积法等,其中光化学反应法是很重要的一种。本论文旨在探索光化学还原合成法可控制备多山丘状Ag纳米颗粒超结构、Ag/Ag2O纳米片、CuxOy纳米片等纳米晶体,并探讨了各种纳米结构的生长机制。通过进一步的固相热分解法,制备了多孔Ag/Ag2O纳米片和多孔Cu O纳米片。主要开展的工作如下:1.光化学还原方法首次制备多山丘状Ag纳米颗粒的超结构:在光化学还原反应中,吸附在Zn O半导体表面的Ag+离子首先被光生电子还原为Ag0,后者进一步生长为Ag纳米颗粒。随后,在螺旋位错的诱导下,现场生成的Ag纳米颗粒通过BCF机制(Burton,Cabrera,and Frank)结晶生长为多山丘状超结构。研究结果显示,这是一个以纳米颗粒为结构单元、在螺旋位错诱导下发生的晶体生长过程(BCF model)。研究还发现,这些在Zn O表面生长的多山丘状Ag纳米颗粒超结构能够精细地调控Zn O的光致发光性能(Photoluminesence,PL)。2.光化学还原法制备Ag/Ag2O纳米片:通过调控UV辐射时间,成功地制备形貌、尺寸可控,直立生长于Zn O薄膜上的Ag/Ag2O纳米片。讨论Ag NO3浓度、UV辐射时间等因素从而探讨Ag/Ag2O纳米片的生长机理。研究发现,Ag/Ag2O纳米片的生长受两种机制控制:首先,光化学还原法现场制备的Ag纳米颗粒通过层层生长(layer-by-layer)机制进一步结晶生长为表面粗糙、边缘不规则且尺寸较小的纳米片;然后,后者在紫外光的照射下进一步转化为表面光滑、边缘整齐规则且尺寸较大的纳米片。通过固相热分解的方法,我们进一步得到了多孔Ag/Ag2O纳米片。与退火之前的Ag/Ag2O纳米片相比,多孔Ag/Ag2O纳米片具更好的SERS活性。3.光化学合成法制备CuxOy纳米片:研究发现,CuxOy纳米片的生长机制与Ag/Ag2O纳米片的生长机制相似,但是在相似的实验条件下,CuxOy纳米片的生长速度要显著快于Ag/Ag2O纳米片,更为深入的生长机制仍然在研究当中。最后,在350℃条件下,通过固相热分解法处理CuxOy纳米片,得到了多孔Cu O纳米片。这些多孔Cu O纳米片在催化、传感领域有着广泛的应用前景。
[Abstract]:Due to its unique surface plasmon resonance (plasmon) resonance surface plasmon resonance (SPRs), copper nanomaterials exhibit excellent physical and chemical properties, especially optical properties.Surface plasmon resonance (SPR) is a series of enhanced spectroscopic techniques, such as surface enhanced Raman and fluorescence enhancement.Using surface plasmon resonance enhanced spectroscopy, scientists have achieved trace detection, even monomolecular detection.In addition, surface plasmon resonance (SPR) has great application value in photocatalytic degradation, infrared hyperthermia and biomarker.The properties of nanomaterials can be controlled by adjusting the composition, morphology, size and space dimension of nanomaterials.The reported researches are mainly focused on gold and silver nanomaterials, but relatively few on Ag2O nanomaterials and copper based nanomaterials.At present, there are many methods used to prepare nanomaterials, including hydrothermal method, pulse-laser deposition method, sol-gel method, electrochemical deposition method, chemical vapor deposition method and so on. Photochemical reaction is one of the most important methods.The aim of this thesis is to explore the controllable preparation of multi-mound Ag / Ag _ 2O nanocrystals by photochemical reduction synthesis, and investigate the growth mechanism of various nanocrystals, such as CuxOy nanocrystals.Porous Ag/Ag2O nanoparticles and porous CuO nanoparticles were prepared by further solid phase thermal decomposition.The main work to be carried out is as follows: 1: 1.In the photochemical reduction reaction, Ag ions adsorbed on the surface of Zn O semiconductors were first reduced to Ag _ 0 by photoelectron, and the latter was further grown into Ag nanoparticles.Subsequently, induced by spiral dislocations, Ag nanoparticles formed in situ grew into multi-hill superstructures through the BCF mechanism of Burton Cabreraragne and Frank.The results show that this is a crystal growth process induced by helical dislocations with nanocrystalline particles as the structure unit.It is also found that these massif Ag nanoparticles can fine regulate the photoluminescence properties of ZnO.Ag/Ag2O nanocrystals were prepared by photochemical reduction method. By controlling UV radiation time, Ag/Ag2O nanowires were successfully prepared with controllable size and upright growth on Zno thin films.The factors such as Ag NO3 concentration and UV radiation time are discussed to study the growth mechanism of Ag/Ag2O nanoparticles.It was found that the growth of Ag- / Ag2O nanoparticles was controlled by two mechanisms: firstly, the Ag nanoparticles prepared by photochemical reduction method were further crystallized and grown into coarse surface, irregular edges and smaller size by layer by layer growth mechanism.Then, the latter is further transformed into a large size nanocrystalline film with smooth surface, regular edges and large size under the irradiation of ultraviolet light.The porous Ag/Ag2O nanocrystals were further obtained by solid phase thermal decomposition.Compared with the Ag/Ag2O nanoparticles before annealing, the porous Ag/Ag2O nanoparticles have better SERS activity. 3.Preparation of CuxOy nanoparticles by photochemical synthesis: it was found that the growth mechanism of CuxOy nanoparticles was similar to that of Ag/Ag2O nanoparticles, but the growth rate of CuxOy nanoparticles was significantly faster than that of Ag/Ag2O nanoparticles under similar experimental conditions.More in-depth growth mechanisms are still being studied.Finally, porous CuO nanoparticles were prepared by solid phase thermal decomposition at 350 鈩，

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