ZnO/Au纳米复合物的制备及光学性质的研究

采用ZnO纳米晶表面还原Au+的方法合成了ZnO/Au纳米复合物,研究了其光学性质。     

水热法合成ZnO纳米棒图案及其场增强效应

利用水热合成方法在图案化的Au岛上合成了ZnO纳米棒图案,采用的溶液体系为六次甲基四胺和硝酸锌溶液,ZnO纳米棒的基底是ITO导电玻璃上的有序Au岛. 由于ZnO的异相成核速度在Au和ITO基底上具有不同的成核速度,因此ZnO优先生长在成核速度快的Au岛上,同时由于受到了溶液中前驱物种扩散的限制,纳米棒继续生长也被受到了约束. 通过调控六次甲基四胺和硝酸锌的浓度,可以调整不同的图案. 此外,利用X射线衍射、光致发光谱和场发射特性性能对水热合成的ZnO纳米棒图案进行了研究. ZnO纳米棒表现出良好的场增强性     

表面等离子体增强氧化锌纳米带发光特性的研究

利用简单的化学气相沉积方法在低温下高产量地合成了ZnO纳米带, 并利用磁控溅射对样品进行表面修饰, 制备了Au-ZnO复合纳米带. 通过扫描电镜、透射电镜及微区拉曼等手段系统地研究了表面修饰对ZnO 纳米材料发光性能的影响.结果表明, 在ZnO纳米带上溅射Au纳米颗粒, 可有效增强其近带边发光并使可见发光强度发生淬灭, 从而增强ZnO纳米带的发光性能. ZnO纳米带发光增强因子η最大可达到85倍. 基于Au纳米颗粒的散射、吸收、Purcell增强因子, 以及Ostwald熟化理论, 又进一步探讨了Au-ZnO复合材料的发光机制. 采用表面等离子体耦合的方法可以有效地提高光电半导体器件的发光效率. 关键词： 表面等离体子 光致发光 氧化锌     

直立Zn_2GeO_4/ZnO纳米棒阵列的制备及其发光性质研究

利用化学气相沉积法(CVD)在表面溅射Au和沉积ZnO籽晶的硅衬底上分别生长高度有序、垂直密布的直立Zn2GeO4/ZnO纳米棒阵列,利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)和光致发光(PL)谱测试手段对所制备样品进行表征和发光特性的研究。所制备的Zn2GeO4/ZnO纳米棒的直径为350~400 nm,高度为10~11μm;室温PL谱观察到3个来源于Zn2GeO4的典型发光峰。最后,对CVD法制备的Zn2GeO4/ZnO纳米棒生长机理进行了分析。该种直立性良好的一维纳米棒材料可以广泛地应用到纳米光电子器件中。     

接触电极对压电纳米发电机性能影响的研究

利用低温水溶液法在柔性PET衬底上生长一维氧化锌(ZnO)纳米结构,并采用XRD、SEM等表征手段分别对生长ZnO纳米结构的晶体结构和表面形貌进行表征与分析。在此基础上,研制出一种基于柔性PET衬底的直流压电纳米发电机。为了提高纳米发电机的发电性能,利用镀Au的ZnO纳米棒阵列作为上电极,制备出具有高性能的新型ZnO纳米发电机,成功地实现了稳定的直流输出信号。该纳米发电机的最高输出电流为330nA,足以驱动一些微纳米器件。     

热处理对ZnO/Au薄膜结构和压电特性的影响

通过射频磁控溅射在氧化硅片表面沉积ZnO/Au薄膜,并通过不同的热处理方式对薄膜进行退火。为了研究退火对ZnO/Au薄膜结构和压电特性的影响,采用X射线衍射分析（XRD）、光学显微镜、场发射扫面电镜（FESEM）和压电力分析仪对薄膜退火前后的材料特性进行了分析。研究发现,热处理能够改善ZnO/Au薄膜的结晶质量。特别是在氮气保护氛围下慢速退火后,薄膜结晶质量有明显改善。但是,热处理导致了薄膜的压电系数d33和d31降低。分析认为,热处理过程中Au原子在ZnO中的易迁移特性破坏了ZnO/Au薄膜的压电性能。     

ZnS修饰对ZnO纳米棒：P3HT复合薄膜I-V性质的影响

本文通过化学浴沉积法获得了直径约为50 nm, 长度约为250 nm的ZnO纳米棒阵列, 引入纳米ZnS对ZnO纳米棒进行表面修饰, 分别制备得到了具有ITO (indium tin oxides)/ZnO/Poly-(3-hexylthiophene) (P3HT)/Au和ITO/ZnO@ZnS/P3HT/Au结构的多层器件. 通过I-V曲线对比讨论了两种结构器件的开启电压, 串联电阻, 反向漏电流及整流比等参数, 认为包含ZnS修饰层器件的开启电压、串联电阻、反向漏电流明显降低, 整流比显著增强, 展现出更优异的电子传输性能. 光致发光光谱分析结果证实由于ZnS使ZnO纳米 棒的表面缺陷产生的非辐射复合被明显抑制, 弱化了电场激发下的载流子陷获, 改善了器件的导电特性. 关键词： ZnO纳米棒阵列 表面修饰 电流-电压特性     

Au/Au同质结的高压水热合成及其光学性能研究

本文通过水热法合成了Au和Au/Au同质结纳米粒子,并用透射电子显微镜(TEM)和紫外可见吸收(UV-vis)光谱对所合成的单分散Au纳米粒子和Au/Au同质结纳米粒子进行了表征。我们的研究发现,十六烷基三甲基溴化铵(CTAB)在Au/Au同质结纳米粒子的合成中起着非常重要的作用,改变CTAB的加入量,Au纳米粒子由单分散Au纳米粒子变成Au/Au同质结纳米粒子。     

热处理对ZnO/Au薄膜结构和压电特性的影响（英文）

通过射频磁控溅射在氧化硅片表面沉积ZnO/Au薄膜,并通过不同的热处理方式对薄膜进行退火。为了研究退火对ZnO/Au薄膜结构和压电特性的影响,采用X射线衍射分析(XRD)、光学显微镜、场发射扫面电镜(FESEM)和压电力分析仪对薄膜退火前后的材料特性进行了分析。研究发现,热处理能够改善ZnO/Au薄膜的结晶质量。特别是在氮气保护氛围下慢速退火后,薄膜结晶质量有明显改善。但是,热处理导致了薄膜的压电系数d33和d31降低。分析认为,热处理过程中Au原子在ZnO中的易迁移特性破坏了ZnO/Au薄膜的压电性能。     

背入射Au/ZnO/Al结构肖特基紫外探测器

设计制作了一种Au/ZnO/Al结构的紫外探测器,光的入射方式采用背入射式。ZnO薄膜是用磁控溅射在蓝宝石衬底上制备的。I-V测试表明:Au与ZnO形成了肖特基接触。得到探测器的光响应峰值在352nm,截止边为382nm,可见抑制比达一个量级。由于该探测器是一种垂直结构器件,对于进一步实现ZnO紫外探测器阵列及单光子探测有很好的研究价值。     

Nanocomposite ZnO/Au formation by pulsed laser irradiation

The ZnO/Au nanocomposite formation involves synthesis of Au and ZnO colloidal solutions by 532 nm pulse laser ablation of metal targets in deionized water followed by laser irradiation of the mixed colloidal solution. The transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM) images show evolution of spherical particles into ZnO/Au nanonetworks with irradiation time. The formation mechanism of the nanonetwork can be explained on the basis of near resonance absorption of 532 nm irradiation by gold nanoparticles which can cause selective melting and fusion of gold nanoparticles to form network. The ZnO/Au nanocomposites show blue shift in the ZnO exciton absorption and red shift in the Au plasmon resonance absorption due to interfacial charge transfer.     

ZnO/Ag纳米复合物的制备及光学性质

采用ZnO纳米晶表面还原Ag+的方法合成了ZnO/Ag纳米复合物,并研究了其光学性质.透射电镜和XRD谱表征了ZnO/Ag纳米复合物的晶体形貌和结构,吸收光谱和荧光光谱证明ZnO和Ag之间存在电子传递.在325 nm激光激发下观察到了ZnO/Ag纳米复合物的表面增强共振拉曼散射.     

Enhanced acetone sensing characteristics by decorating Au nanoparticles on ZnO flower-like structures

A well-organized hierarchical structure of ZnO was developed by chemical bath deposition and used as templates for making gold-coated ZnO (Au/ZnO) hybrid nanostructures. The coverage of Au nanoparticles (Au NPs) on ZnO was controlled by changing the amount of the Au precursor. The Au/ZnO hybrids were applied as gas sensing materials to detect acetone. The improved sensor response, selectivity and short response, and recovery time to acetone vapor due to Au NPs on ZnO nanostructures has been observed and explained by considering the formation of Au/ZnO heterostructures, which are favorable for the diffusion of gas molecules. In addition, the dependence of Au amount on gas sensor properties was systematically investigated. ZnO decorated by 6 wt% Au NPs displayed a 9.05-fold enhancement in gas response to 100 ppm of acetone at 280 °C compared to pristine ZnO.     

Synthesis and characterisation: Zinc oxide–sulfide nanocomposites

A novel synthesis method is presented for the preparation of nanosized-semiconductor zinc oxide–sulphide (ZnO/ZnS) core–shell nanocomposites, both formed sequentially from a single-source solid precursor. ZnO nanocrystals were synthesized by a simple co-precipitation method and ZnO/ZnS core–shell nanocomposites were successfully fabricated by sulfidation of ZnO nanocrystals via a facile chemical synthesis at room temperature. The as-obtained samples were characterized by X-ray diffraction and transmission electron microscopy. The results showed that the pure ZnO nanocrystals were hexagonal wurtzite crystal structures and the ZnS nanoparticles were sphalerite structure with the size of about 10 nm grown on the surface of the ZnO nanocrystals. Optical properties measured reveal that ZnO/ZnS core–shell nanocomposites have integrated the photoluminescent effect of ZnO and ZnS. Based on the results of the experiments, a possible formation mechanism of ZnO/ZnS core–shell nanocomposites was also suggested. This treatment is suggested to improve various properties of optoelectronically valuable ZnO/ZnS nanocomposites. These nanosized semiconductor nanocomposites can form a new class of luminescent materials for various applications.     

Synthesis and characterization of ZnO-Ag core-shell nanocomposites with uniform thin silver layers

This paper presents an investigation on the synthesis and characterization of ZnO-Ag core-shell nanocomposites. ZnO nanorods were employed as core material for Ag seeds, and subsequent nucleation and growth of reduced Ag by formaldehyde formed the ZnO-Ag core-shell nanocomposites. The ZnO-Ag nanocomposites were annealed at different temperature to improve the crystallinity and binding strength of Ag nanoparticles. The morphology, microstructure and optical properties of the ZnO-Ag core-shell nanocomposites were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, ultraviolet-visible (UV-vis) absorption and photoluminescence measurement. It was demonstrated that very small face-center-cubic Ag nanoparticles were coated on the surface of ZnO nanorods. The ultraviolet absorption and surface plasmon absorption band of ZnO-Ag core-shell nanocomposites exhibited some redshifts relative to pure ZnO nanorods and monometallic Ag nanoparticles. The coating of Ag nanocrystals onto the ZnO nanorods completely quenched the photoluminescence. These observations reflected the strong interfacial interaction between ZnO nanorods and Ag nanoparticles. The effect of Ag coating thickness on the morphology and optical properties of ZnO-Ag core-shell nanocomposites was also investigated. Moreover, the growth mechanism of ZnO-Ag core-shell nanocomposites was also proposed and discussed in detail.     

First-principles studies on the Au surfactant on polar ZnO surfaces

The surfactant effect of Au in ZnO nanostructures growth is studied using first-principles slab calculations based on density functional theory. The atomic structure and electronic properties of one monolayer of Au atoms on polar ZnO surfaces are examined. It is found that (1) one monolayer (ML) of Au capping layer on the ZnO polar surfaces may modify the growing properties of ZnO nanostructures by enhancing the binding energy by 0.41 eV/atom for Zn adsorption on the polar surfaces; (2) the Au adlayer on the polar ZnO surfaces seems more active for the adsorption of Zn atoms, which may be at the very heart of the effect that Au acts as catalyst for the growth of the ZnO nanostructures; and (3) total energy calculations show that the gold on-top geometry is energetically favorable than the gold diffused geometry, which may be useful to understand the phenomenon that Au particles are only found at the end of ZnO nanostructures during the growth process.     

Visible-light photocatalysis of ZnO deposited on nanoporous Au

ZnO deposited on nanoporous Au showed photocatalytic decomposition toward methyl orange under visible light, unlike ZnO sputtered on flat Au without a nanoporous structure. First-principles calculations suggested that the surface lattice disorder in nanoporous Au induced a band gap narrowing and a large built-in electric field in the adjacent ZnO, resulting in the visible-light photocatalytic response.     

紫外发光增强的石墨烯-氧化锌纳米复合物

采用溶剂热法在相同条件下分别制备了纯ZnO和石墨烯-氧化锌纳米复合物,通过SEM、TEM、拉曼和红外光谱等手段,对纳米复合物样品进行了形貌和结构表征。实验结果显示ZnO纳米颗粒成功地分散在少层石墨烯上。通过对比纯ZnO与复合物的形貌和光致发光谱,发现在没有石墨烯时,ZnO能够择优取向生长成六方棱柱,紫外发光峰弱且宽;在有石墨烯时,ZnO聚集成表面不规则的球形颗粒,紫外发光峰强且窄。上述结果表明ZnO形貌的变化和石墨烯的等离子体效应共同影响了ZnO的紫外发光,但石墨烯的表面等离子体效应起主导作用。     

Surfactant Effects of Au on Polar ZnO Surfaces

The electronic properties of one monolayer of Au atoms on polar ZnO surfaces are examined by first-principles slab calculations. It is found that an Au ad-layer on top of the surface is energetically more favourable than other gold diffused cases, and Au capping layer on the ZnO polar surfaces may modify the growing properties of ZnO nanostructures by enhancing the binding energy.