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1.
潘国卫 《物理化学学报》2006,22(9):1147-1150
在低真空的CVD系统中直接热蒸发SiO粉末并以金为催化剂在硅衬底上制备出大量长达几十微米的硅纳米线(SiNWs), 通过X 射线衍射谱(XRD)、场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)、选区电子衍射仪(SAED)和Raman光谱等技术对硅纳米线进行形貌及结构分析. 实验结果表明, 在不同生长温度下制备得到的硅纳米线质量不同, 其中在700 ℃温区生长的硅线质量最好; 与晶体硅Raman的一级散射特征峰(TO)520.3 cm−1相比, 纳米硅线的Raman特征峰(TO)红移至514.8 cm−1.  相似文献   

2.
取向碳纳米管/硅纳米线复合阵列的制备   总被引:3,自引:0,他引:3       下载免费PDF全文
在阳极氧化铝模板(AAO)的取向微孔内, 利用化学气相沉积(CVD) 技术首先制备了两端开口高度取向的碳纳米管阵列, 再在碳纳米管中间的孔洞内沉积硅纳米线, 成功制备了碳纳米管/硅纳米线(CNTs/SiNWs)核鞘复合阵列结构. 用SEM, TEM, XRD等仪器分析了CNTs/SiNWs核鞘复合阵列和沉积在碳纳米管孔洞内的硅纳米线的生长特性和晶体结构, 利用I-V关系和Fowler-Nordheim方程研究了其场发射(FE)特性, 用荧光光谱分析仪分析了复合阵列的荧光(PL)特性. 证明了模板法制备的CNTs/SiNWs核鞘复合阵列结构可用来制作具有金属/半导体(M/S)特性的纳米PN结, 该复合阵列结构也使SiNWs包覆在CNTs惰性鞘内, 可防止SiNWs在空气中的进一步氧化. 制备出的CNTs/SiNWs核鞘复合阵列结构生长方向高度有序, 直径和长度易于控制, 极少产生其他制备方法中出现的纳米结构弯曲和相互缠绕现象.  相似文献   

3.
张晓丹  田华  贺军辉  曹阳 《化学学报》2013,71(3):433-438
以十二烷基硫酸钠(SDS)作为保护剂, 利用贵金属阳离子(Mn+)与HF处理后的硅纳米线(SiNWs)之间的氧化还原反应, 在SiNWs表面负载了贵金属纳米粒子. 通过调控SDS/Mn+物质的量比、反应物浓度、反应温度等实验参数, 制备出了金属纳米粒子粒径均一且负载密集的AuNPs/SiNWs, PtNPs/SiNWs复合材料. 将AuNPs/SiNWs复合材料应用在亚甲基蓝的还原反应, 实验结果显示, 60 min内AuNPs/SiNWs可以将55%的亚甲基蓝还原, 表明AuNPs/SiNWs具有良好的催化活性. 这种复合材料易于从反应溶液中分离出来, 可以实现纳米催化剂的循环使用.  相似文献   

4.
在1000 ℃用活性炭把二氧化锡粉末还原成单质锡, 锡作为催化剂, 硅片作为硅源同时作为收集衬底, 在硅片上制备出了非晶SiO2纳米灯笼. 灯笼的一端连在硅片上, 另一端为一个锡球, 中间是一些圆弧状的SiO2纳米线把两端相连. 纳米灯笼具有良好的对称性. 利用扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、选区电子衍射(SAED) 和HRTEM自带的能谱分析仪(EDS)对样品的表面形貌、微观结构和成分进行了分析研究. 结果表明, 灯笼中SiO2纳米线为非晶态, 结点是晶态锡, 结点表面覆盖一层非晶态的硅的氧化物. 结合实验条件对纳米灯笼的生长机理进行了讨论, 提出了纳米灯笼生长的一个模型.  相似文献   

5.
二维纳米材料具有独特的结构和优异的性能,在电子学及光电子学领域有广泛的应用前景,但关于硫化镉二维纳米材料的制备及性能研究还鲜有报道。本文首次采用范德华外延生长技术,在氟金云母片衬底上制备了硫化镉二维纳米片。通过扫描电子显微镜、透射电子显微镜、原子力显微镜、X射线粉末衍射仪和拉曼光谱仪等分析手段对产物的形貌、厚度、晶体结构、成分等进行了系统的研究。结果表明,纳米片具有六方纤锌矿晶体结构,尺寸约为几个微米,厚度约为几十纳米。范德华外延生长技术在硫化镉二维单晶纳米片制备上的成功应用,为其它二维非层状材料的制备提供了新的思路,并使其在高性能电子和光电子器件上的应用成为了可能。  相似文献   

6.
化学气相沉积法制备氧化锡自组装纳米结构   总被引:2,自引:0,他引:2  
采用化学气相沉积法在镀有5-10 nm厚金膜的SiO2衬底上, 通过控制生长条件, 实现了二氧化锡纳米结构的自组装生长, 成功制备出了莲花状和菊花状的二氧化锡自组装纳米结构. 利用扫描电子显微镜、X射线衍射等表征分析手段对样品的表面形貌、结构及成份进行表征和研究. 并在此基础上, 讨论了两种自组装纳米结构的生长机制.  相似文献   

7.
张晓丹  曹阳  贺军辉 《化学学报》2009,67(12):1277-1284
在溶液中以正己硫醇作稳定剂, 利用HAuCl4与HF处理后的硅纳米线(SiNWs)的氧化还原反应, 在SiNWs表面负载金纳米粒子(AuNPs). 通过调整HAuCl4的浓度, 得到了AuNPs粒径从3.2到7.0 nm的AuNPs/SiNWs复合结构, 并对这种复合结构进行了紫外-可见吸收光谱和荧光光谱研究. 紫外-可见吸收光谱研究表明, 负载不同粒径的AuNPs的SiNWs在530~580 nm间有明显的由AuNPs表面等离子体共振引起的吸收, 且随着AuNPs粒径的增加, 该吸收峰发生红移. 负载前后的荧光光谱表明, 在红光和绿光区负载AuNPs的SiNWs的荧光峰与HF处理后SiNWs的荧光峰峰形相当, 峰位变化不大; 但在蓝光区, 不同于HF处理前后SiNWs的发射峰(464 nm左右), 负载了AuNPs的SiNWs在423 nm的位置处出现了强荧光峰, 这个峰是AuNPs费米能级的电子与sp或d带的空穴辐射复合产生的.  相似文献   

8.
为了研究复合光催化剂在光催化中的制氢效率,采用水热法制备了Mo S2纳米片,然后通过水热法在Mo S2纳米片上负载了TiO_2纳米颗粒,形成了Mo S2/TiO_2异质结复合催化剂。采用冷场发射扫描电子显微镜(FE-SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、紫外-可见吸收光谱(UV-Vis)、拉曼光谱(Raman),X射线光电子能谱(XPS)对材料的结构和光学性能表征并进行分析。通过光催化制氢测试对光催化剂进行评价,实验结果表明,在波长为365 nm的紫外光照射下,最高光催化制氢速率为1004μmol·h-1·g-1,对应的催化剂的Mo S2含量为30%,其催化速率远大于单一的Mo S2和TiO_2,表明Mo S2/TiO_2复合催化剂在紫外光照下能显著提高光催化产氢性能。基于Mo S2/TiO_2复合光催化剂优越的光催化产氢性能,本文对复合光催化剂的产氢机理做了研究和分析。  相似文献   

9.
利用包括磁控溅射和热氧化的两步法在Si(111)衬底上制备了Sn掺杂ZnO纳米针.首先用磁控溅射法在Si(111)衬底上制备Sn:Zn薄膜,然后在650℃的Ar气氛中对薄膜进行热氧化,制备出Sn掺杂ZnO纳米针.样品的结构、成分和光学性质采用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)、能量散射X射线(EDX)谱和光致发光(PL)光谱等技术手段进行分析.结果表明,制备的样品为具有六方纤锌矿结构的单晶Sn掺杂ZnO纳米针,Sn掺杂量为2.5%(x,原子比),底部和头部直径分别为200-500 nm和40 nm,长度为1-3μm,结晶质量较高.室温光致发光光谱显示紫外发光峰比纯ZnO的发光峰稍有蓝移,这可归因于能谱分析中探测到的Sn的影响.基于本实验的实际条件,简单探讨了Sn掺杂ZnO纳米针的生长机制.  相似文献   

10.
使用稀土元素Tb作催化剂, 通过氨化溅射在Si(111)衬底上的Ga2O3/Tb薄膜, 成功制备出GaN纳米棒. X射线衍射测试显示, GaN纳米棒具有六方结构. 利用扫描电子显微镜和高分辨透射电子显微镜观察分析得出, 纳米棒为单晶GaN, 纳米棒的直径为50-150 nm, 长度约10 μm. 光致发光谱在368.6 nm处有一强的紫外发光峰, 说明纳米棒具有良好的发光特性. 讨论了GaN纳米棒的生长机制.  相似文献   

11.
原位反应合成Mo-Si化合物系复合材料   总被引:4,自引:0,他引:4  
采用反应烧结法原位合成了Mo Si系化合物复合材料,利用X射线衍射仪、扫描电镜和电子探针等考察了材料的显微结构和相组成.结果表明,随原料粉中Mo含量的增加, Mo Si系反应生成物依次向MoSi2→Mo5Si3→Mo3Si变化;各相分布较为均匀,组织致密,晶粒细小.  相似文献   

12.
《Chemical physics letters》2003,367(5-6):528-532
Array-orderly single crystal silicon nano-wires (SiNWs) using self-organized nano-holes of anodically oxidized aluminum were fabricated. By field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM), the well-orderly single crystal SiNWs arrays were observed. The interval of the SiNWs is excellent symmetrical and consentaneous. The diameter and the length are around 35 nm and 4 μm, respectively. Furthermore, the energy dispersive X-ray spectroscopy analysis (EDX) indicated that the SiNWs consist of silicon core and silicon oxide sheath mainly. The Raman scattering was also carried out to analyze the structure of the oriented SiNWs. Finally, the growth mechanism of the SiNWs was discussed.  相似文献   

13.
纳米材料,包括尺寸为纳米量级的超细微粒?线?薄膜?量子阱和超晶格等引起了人们广泛的重视 [1,2] ?其中 , 半导体纳米微粒和由其构成的纳米固体结构开辟了材料科学研究的新领域?硫化镉 (CdS) 作为一种重要的Ⅱ - Ⅵ族无机半导体材料 , 具有独特的光电性质 , 在光电化学电池和多相光催化反应中都有广泛应用?近年来 , 已有大量关于合成 CdS 纳米结构的文献报导 [3~12] , 所采用的方法如反胶束法?单分子膜法?自组装法以及电化学沉积法等 , 其中非水电解与模板技术相结合的制备方法引起了人们高度的重视并且被广泛的采用?自从 Baranski 等在上…  相似文献   

14.
Silicon nanowires (SiNWs) have been fabricated by chemical vapor deposition at ambient pressure using SiCl(4) as a silicon source and mesophase carbon microbead powder as a substrate without any templates and/or metal catalysts. The SiNWs have a crystalline core with a very thin amorphous SiO(x) sheath. The obtained SiNWs are homogeneous with average diameters below 50 nm and lengths up to micrometers. Temperature and time effects on the growth of SiNWs were systematically studied. Higher reaction temperatures and longer reaction times resulted in larger diameters and higher yields of SiNWs. SiNWs with a better crystallinity can be obtained at higher temperatures and longer reaction times. The obtained SiNWs were characterized by field-emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and transmission electron microscopy.  相似文献   

15.
The location‐controlled epitaxial growth of vertically aligned Si nanowire (v‐SiNW) arrays over large surface area was investigated with Au nanodisks (AuNDs) patterned by KrF stepper lithography. There are two steps for synthesizing v‐SiNWs from an AuND pattern: annealing and growth. The annealing process induces the formation of a single Au nanoparticle (AuNP) from an AuND pattern, which consists of several cracked AuNPs. Here, the oxide layer between the AuNDs and Si substrate is necessary for impeding the diffusion of Si atoms into the AuNPs. However, the oxide layer must be removed for properly aligned epitaxial SiNW growth. These SiNW arrays in large area can contribute highly to improve a nanowire‐based engineering by controlling the location of SiNWs with consistent pitch.  相似文献   

16.
A systematic study of the etching behavior, in terms of three-dimensional profiles, of one-dimensional (1-D) silicon nanowires (SiNWs) in NH(4)F-buffered hydrofluoric acid (BHF) solutions of varying concentrations and pH values and the surface speciations of the resulting etched SiNW surfaces, as characterized by attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, is reported. It was found that SiNWs are stable only in relatively narrow pH ranges of the BHF solutions. The results are rationalized in terms of a "double passivation" model. When SiNWs are etched in BHF solutions with pH values of 1-3, the surfaces are passivated with hydrogen (inner layer) giving rise to surface moieties such as Si-H(x) species (x = 1-3); at high HF concentrations, the H-terminated Si surfaces are covered with a hydrogen bonding network of HF and related molecules (oligomers, etc.), providing an outer-layer passivation. When SiNWs are etched in BHF solutions with pH values of 11-14 (by adding a strong base such as NaOH), the surfaces are oxygen-terminated with surface moieties such as Si-(O(-))(x)() species (x = 1-3); at high NH(4)F concentrations, the negatively charged Si surfaces are stabilized by NH(4)(+) ions via ionic bonding, again providing outer-layer passivation. In BHF solutions with pH values of 3-11, the surface speciation, consisting of Si-(OH)(x)(O(-))(y) (x + y = 1-3) species, is unstable and etched away rapidly. The surface speciations of SiNWs etched in various BHF solutions were explored via ATR-FTIR spectroscopy. It was found that, while etching SiNWs with HF-rich BHF solutions with pH < 4 gave rise to Si-H(x)() surface species, no surface Si-H(x) species were observed with SiNWs etched in BHF solutions with pH >/= 4 (HF/NH(4)F /= 4 on the other. These two factors, among others, contribute to the rapid hydrolysis of the surface Si-H(x)() species (and the etching of the SiNWs), particularly in BHF solutions with low HF/NH(4)F ratios and high pH values (pH >/= 4).  相似文献   

17.
Taper- and rodlike Si nanowires (SiNWs) are synthesized successfully on Si and Si(0.8)Ge(0.2) substrates. The growth mechanisms of taper- and rodlike SiNWs are proposed to be oxide-assisted growth (OAG) and vapor-liquid-solid (VLS) growth, respectively. For taperlike SiNWs annealed at 1200 degrees C for 3 h, the emission peaks are found at 772, 478, and 413 nm. On the other hand, for rodlike SiNWs annealed at 1200 degrees C for 4 h, emission peaks are found at 783, 516, and 413 nm. From the field-emission measurements, the taperlike Si nanowires exhibit superior field-emission behavior with a turn-on field of 6.3-7.3 V/mum. The field enhancement, beta, has been estimated to be 700 and 1000 at low and high fields, respectively. The excellent field-emission characteristics are attributed to the perfect crystalline structure and the taperlike geometry of the Si nanowires.  相似文献   

18.
The effect of 1,3-dioxolane (DOL) based electrolyte solutions (DOL/LiTFSI and DOL/LiTFSI-LiNO(3)) on the electrochemical performance and surface chemistry of silicon nanowire (SiNW) anodes was systematically investigated. SiNWs exhibited an exceptional electrochemical performance in DOL solutions in contrast to standard alkyl carbonate solutions (EC-DMC/LiPF(6)). Reduced irreversible capacity losses, enhanced and stable reversible capacities over prolonged cycling, and lower impedance were identified with DOL solutions. After 1000 charge-discharge cycles (at 60 °C and a 6 C rate), SiNWs in DOL/LiTFSI-LiNO(3) solution exhibited a reversible capacity of 1275 mAh/g, whereas only 575 and 20 mAh/g were identified in DOL/LiTFSI and EC-DMC solutions, respectively. Transmission electron microscopy (TEM) studies demonstrated the complete and uniform lithiation of SiNWs in DOL-based electrolyte solutions and incomplete, nonuniform lithiation in EC-DMC solutions. In addition, the formation of compact and uniform surface films on SiNWs cycled in DOL-based electrolyte solutions was identified by scanning electron microscopic (SEM) imaging, while the surface films formed in EC-DMC based solutions were thick and nonuniform. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy were employed to analyze the surface chemistry of SiNWs cycled in EC-DMC and DOL based electrolyte solutions. The distinctive surface chemistry of SiNWs cycled in DOL based electrolyte solutions was found to be responsible for their enhanced electrochemical performances.  相似文献   

19.
A hybrid preparative method was developed to prepare organosulfur-functionalized Au nanoparticles (NPs) on silicon nanowires (SiNWs) by reacting HAuCl(4) with SiNW in the presence of thiol. A number of organosulfur molecules-dodecanethiol, hexanethiol, 1,6-hexanedithiol, and tiopronin-were used to functionalize the Au surface. Size-selected NPs ranging from 1.6 to 7.5 nm were obtained by varying the S/Au ratio and the concentration of HAuCl(4). This method was further extended to the preparation Pd and Pd-Au bimetallic NPs on SiNWs. The morphology of the metal nanostructures was examined by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The local structure and bonding of the SiNW-supported metal nanostructures were studied using X-ray absorption fine structures (XAFS) [including both X-ray near-edge structures (XANES) and extended X-ray absorption fine structures (EXAFS)] at the Au L(3)-, Pd K-, S K-, and Si K-edges. It was also found that the annealing of the thiol-capped Au NPs up to 500 degrees C transforms the surface of the thiol-capped NPs to gold sulfide, as identified using Au L(3)- and S K-edge XANES. We also illustrate that this preparative approach can be used to form size-controllable Au NPs on carbon nanotubes.  相似文献   

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