树枝状Ag基底的制备及其SERS活性研究

研究了一种表面增强拉曼散射(SERS)活性Ag基底的制备新方法。通过电化学方法和液相生长方法相结合在金属Al表面制备SERS活性Ag膜。用扫描电子显微镜(SEM)表征Ag膜的表面形貌,以结晶紫(C25 H30N3Cl·H2O)为拉曼探针分子,研究了基底的SERS增强效果。研究表明:结晶紫分子吸附在Ag膜表面的SERS强度随电沉积时间的增加呈现先增强后减弱的趋势;进一步的Ag增强剂和引发剂的混合溶液对电沉积Ag膜的浸泡处理可以调节基底Ag膜的结构形态,增强电沉积基底Ag膜的SERS活性。     

癸烷硫醇修饰的金/银SERS衬底用于PCB-77检测的研究

通过模板法制备了强SERS活性的“球加片”Au/Ag纳米结构阵列,并利用这种纳米衬底对PCB-77分子的SERS光谱进行了研究。结果表明,尽管该纳米结构能够检测到PCB-77分子的SERS特征峰,但信噪比低。利用癸烷硫醇中的巯基与贵金属之间相互作用,实现了癸烷硫醇分子对纳米结构表面的功能化修饰,研究发现此时PCB-77分子的SERS光谱质量得到了明显改善。并且,这种“球加片”衬底的癸烷硫醇分子最优修饰时间为36小时,利用经36小时修饰后的纳米衬底,极大地提高了PCB-77的SERS光谱特征峰的强度。     

自组装法制备团簇Ag纳米结构衬底及其SERS

采用自组装方法,在3-Aminopropyltrimethoxysilane(APS)分子修饰后的玻璃衬底表面,获得了二维Ag纳米结构衬底。在波长为532nm激光激发下,研究了沉积在衬底表面的Rhodamine 6G(Rh6G)分子的拉曼光谱特性。结果表明,制备的二维Ag纳米结构衬底具有强的拉曼增强特性,增强因子可以达到107倍。这说明,在外光场作用下,制备的Ag纳米结构衬底表面能够形成的强局部电磁场分布,可以有效提升探针分子的光谱辐射效率,从而获得高增强拉曼散射。     

自组装法制备团簇Ag纳米结构衬底及其SERS

采用自组装方法,在3-Aminopropyltrimethoxy silane(APS)分子修饰后的玻璃衬底表面,获得了二维Ag纳 米结构衬底。在波长为532nm激光激发下,研究了沉积在衬底表面的 Rhodamine 6G(Rh6G)分子的拉曼光谱特性。结 果表明,制备的二维Ag纳米结构衬底具有强的拉曼增强特性,增强因子可以达到 10⁷ 倍。这说明,在外光场作用下,制备的Ag纳米结构衬底表面能够形成的强局部电磁场分布, 可以有效提升探针分子的光谱辐射效率,从而获得高增强拉曼散射。     

碳纳米管和金属纳米粒子复合结构的拉曼光谱特性

提出了一种基于碳纳米管和金属纳米粒子的表面增强拉曼基底,并进行了实验研究。采用化学方法制备了单壁和多壁碳纳米管薄膜;利用离子溅射方法在碳纳米管薄膜上形成Au纳米粒子,构成基于碳纳米管和金属纳米粒子复合结构的表面增强拉曼散射基底。对此样品进行了扫描电子显微镜(SEM),反射谱、拉曼谱等表征测试。研究表明,该基底由于碳纳米管极大的比表面积,可吸附更多的金属纳米粒子,增强拉曼散射信号强度。     

Ag纳米粒子修饰多模光纤的拉曼增强特性实验

为了分析研究光纤表面增强拉曼散射(SERS)探针 的拉曼增强特性,采用简单廉价的化学方法制备Ag纳米颗粒修饰 光纤SERS探针,采用罗丹明6G(R6G,Rhodamine 6G)作为探针分子进行了不同浓度R6G溶 液(10－7~10－9M)的拉曼测试实 验和浓度为10－6M的R6G溶液的Time-course SERS Mapping实验,研究了该光纤 SER S探针的拉曼增强特性,制备的光纤SERS 探针样品检测R6G的极限浓度低至10－9M;在Time-course SE RS Mapping实验中,分 析验证了探针分子溶液蒸发过程对光纤 SERS探针的拉曼增强特性的影响。研究表明,由于制备的光纤SERS探针对荧光噪声没有抑 制作用,导致所测得探针分子 的拉曼光谱受探针分子溶液状态、测试方式的极大影响。当溶液充足时(浸泡状态),所测 光谱信号荧光噪声与有效拉曼光 谱信号都比较大;在溶液干燥过程中,所测光谱信号荧光噪声与有效拉曼光谱信号都减少, 但荧光噪声减小幅度远大于拉曼光谱信号。     

激光诱导银纳米颗粒薄膜和微结构

利用可见激光诱导化学沉积方法在玻璃基底上制备纳米银薄膜和微结构。玻璃样品池中装满柠檬酸钠和硝酸银的混合透明溶液,当一束可见连续激光正入射样品池一段时间后,在辐照区域的玻璃内壁上便可以形成一层光亮的银膜。银膜沉积的速度受到激光功率密度、激光波长、辐照时间以及混合溶液的浓度等条件的影响。利用X射线衍射、原子力显微镜和拉曼光谱仪等手段对制备的薄膜的成分、表面形貌和拉曼活性等性质进行了表征和分析。利用此方法制备的银膜具有良好的表面增强拉曼散射活性。同时,利用双光束干涉的方法在玻璃基底上诱导出不同周期的银纳米颗粒光栅。     

贵金属纳米颗粒/石墨烯复合基底SERS研究进展

由于贵金属纳米颗粒/石墨烯复合基底可为喇曼光谱分析技术提供灵敏度高、稳定性好、生物相容性好的基底而备受关注。首先从电磁原理和化学原理两个角度出发,系统地探讨了贵金属纳米颗粒/石墨烯复合基底表面增强喇曼散射(SERS)的机理,进而概述了石墨烯及贵金属纳米颗粒的制备方法及其性能特征,并详细介绍了化学气相沉积法制备石墨烯和物理法制备贵金属纳米颗粒的过程。在此基础上,对不同贵金属纳米颗粒/石墨烯复合基底SERS的国内外研究进展进行了综合的阐述和分析,主要介绍了贵金属Ag,Au和Pt的纳米颗粒复合体系,最后对贵金属纳米颗粒/石墨烯复合基底SERS技术在各个领域的应用及其发展前景进行了展望。     

一种新的具有双面活性的SERS基底

用二次氧化的方法制得了孔径均一、排列规则的阳极氧化铝模板（AAO,anodic aluminumoxide）。利用磁控溅射的方法,银纳米颗粒被溅射在模板的表面以及孔洞里面,在模板的一面形成一层粗糙的银表面,当把模板放入一定浓度的NaOH溶液中,反面的Al2O3模板被部分地溶解后露出针尖状的银纳米线阵列。用结晶紫作为探针分子,在粗糙银表面（正面）和针尖状的银纳米线阵列面（反面）得到了不同的表面增强拉曼散射（SERS,surface enhanced Raman scattering）光谱,从而证明了两面具有不同的SERS机制。分析表明：正面粗糙的银表面是吸附增强,而反面在存在吸附增强的同时起主要作用的是针尖状的银纳米线阵列构成的天线模型所产生的非吸附的增强。针尖末端的曲率半径极小,会产生极强的局域电磁场,处于这个场中的分子的信号就被大大增强了。     

Self-Bank 银纳米粒子导电膜的制备

研究了一种制备金属纳米粒子导电膜的新方法 self-bank 方式.该金属导电层利用 self-bank 效应自发产生边界.基板上先沉积一层均匀的 PMMA 作为绝缘层.银纳米颗粒分散在适当的溶剂中形成纳米粒子悬浊液,该溶剂可以同时溶解PMMA.当纳米颗粒悬浊液滴在基板上的PMMA层上时,溶剂溶解掉该区域的 PMMA 并在该区域的边缘构成导电层的边界,同时改善了金属膜的成膜均匀性和导电性.最后 PMMA 通过退火去除后,以此形成 self-bank 的金属导电层.     

Cucurbiturils-Mediated Noble Metal Nanoparticles for Applications in Sensing,SERS, Theranostics,and Catalysis

Noble metal nanoparticles (NMNPs), which spring up like mushrooms, are gaining momentum owing to their unique physicochemical characteristics. Cucurbiturils, a class of synthetic macrocycles with intriguing and peculiar host–guest properties, have stimulated tremendous research interest in recent years. The marriage of NMNPs with cucurbiturils is expected to integrate and enhance the excellent characteristics of both components, e.g., precisely controlled particle size, stability, assembly, surface functionality, biocompatibility, tunable optical properties, and high catalytic activities. This review systematically outlines the recent progress on the fabricating strategies and important applications of cucurbiturils-mediated NMNPs in sensing, surface-enhanced Raman scattering, theranostics, and catalysis. A brief outlook on the future development of cucurbiturils-mediated NMNPs is also presented.     

Highly Conductive Ordered Mesoporous Carbon Based Electrodes Decorated by 3D Graphene and 1D Silver Nanowire for Flexible Supercapacitor

Ordered mesoporous carbon (OMC) is considered one of the most promising materials for electric double layer capacitors (EDLC) given its low‐cost, high specific surface area, and easily accessed ordered pore channels. However, pristine OMC electrode suffers from poor electrical conductivity and mechanical flexibility, whose specific capacitance and cycling stability is unsatisfactory in flexible devices. In this work, OMC is coated on the surface of highly conductive three‐dimensional graphene foam, serving as both charge collector and flexible substrate. Upon further decoration with silver nanowires (Ag NWs), the novel architecture of Ag NWs/3D‐graphene foam/OMC (Ag‐GF‐OMC) exhibits exceptional electrical conductivity (up to 762 S cm^?1) and mechanical robustness. The Ag‐GF‐OMC electrodes in flexible supercapacitors reach a specific capacitance as high as 213 F g^?1, a value five‐fold higher than that of the pristine OMC electrode. Moreover, these flexible electrodes also exhibit excellent long‐term stability with >90% capacitance retention over 10 000 cycles, as well as high energy and power density (4.5 Wh kg^?1 and 5040 W kg^?1, respectively). This study provides a new procedure to enhance the device performance of OMC based supercapacitors, which is a promising candidate for the application of flexible energy storage devices.     

A Generic Synthetic Approach to Large‐Scale Pristine‐Graphene/Metal‐Nanoparticles Hybrids

The homogeneous attachment of metal‐nanoparticles (metal‐NPs) on pristine‐graphene surface to construct pristine‐graphene/metal‐NPs hybrids is highly expected for application in many fields such as transparent electrodes and conductive composites. However, it remains a great challenge since the pristine‐graphene is highly hydrophobic. Here, an environmentally friendly generic synthetic approach to large‐scale pristine‐graphene/metal‐NPs hybrids is presented, by a combinatorial process of exfoliating expanded graphite in N‐methyl pyrrolidone via sonication and centrifugation to achieve the pristine‐graphene, and attaching pre‐synthesized metal‐NPs on the pristine‐graphene in ethanol via van der Waals interactions between the metal‐NPs and the pristine‐graphene. Nanoparticles of different metals (such as Ag, Au, and Pd) with various morphologies (such as sphere, cube, plate, multi‐angle, and spherical‐particle assembling) can be homogeneously attached on the defect‐free pristine‐graphene with controlled packing densities. Both the pristine‐graphene and the metal‐NPs preserve their original intrinsic structures. The as‐synthesized pristine‐graphene/Ag‐NPs hybrids show very high surface‐enhanced Raman scattering activity due to the combined effects of large surface area of the pristine‐graphene to adsorb more target molecules and the electromagnetic enhancement of the Ag‐NPs. This large‐scale synthesis of the pristine‐graphene/metal‐NPs hybrids with tunable shape and packing density of metal‐NPs opens up opportunities for fundamental research and potential applications ranging from devices to transparent electrodes and conductive composites.     

Arrays of Cone‐Shaped ZnO Nanorods Decorated with Ag Nanoparticles as 3D Surface‐Enhanced Raman Scattering Substrates for Rapid Detection of Trace Polychlorinated Biphenyls

A new, highly sensitive and uniform three‐dimensional (3D) hybrid surface‐enhanced Raman scattering (SERS) substrate has been achieved via simultaneously assembling small Ag nanoparticles (Ag‐NPs) and large Ag spheres onto the side surface and the top ends of large‐scale vertically aligned cone‐shaped ZnO nanorods (ZnO‐NRs), respectively. This 3D hybrid substrate manifests high SERS sensitivity to rhodamine and a detection limit as low as 10^?11 M to polychlorinated biphenyl (PCB) 77—a kind of persistent organic pollutants as global environmental hazard. Three kinds of inter‐Ag‐NP gaps in 3D geometry create a huge number of SERS “hot spots” that mainly contribute to the high SERS sensitivity. Moreover, the supporting chemical enhancement effect of ZnO‐NRs and the better enrichment effect ascribed to the large surface area of the substrate also help to achieve a lower detection limit. The arrays of cone‐shaped ZnO‐NRs decorated with Ag‐NPs on their side surface and large Ag spheres on the top ends have potentials in SERS‐based rapid detection of trace PCBs.     

Nanoscale Graphene Doped with Highly Dispersed Silver Nanoparticles: Quick Synthesis,Facile Fabrication of 3D Membrane‐Modified Electrode,and Super Performance for Electrochemical Sensing

The performance of graphene‐based hybrid materials greatly depends on the dispersibility of nanoscale building blocks on graphene sheets. Here, a quick green synthesis of nanoscale graphene (NG) nanosheets decorated with highly dispersed silver nanoparticles (AgNPs) is demonstrated, and then the electrospinning technique to fabricate a novel nanofibrous membrane electrode material is utilized. With this technique, the structure, mechanical stability, biochemical functionality, and other properties of the fabricated membrane electrode material can be easily controlled. It is found that the orientations of NG and the dispersity of AgNPs on the surface of NG have significant effects on the properties of the fabricated electrode. A highly sensitive H₂O₂ biosensor is thus created based on the as‐prepared polymeric NG/AgNP 3D nanofibrous membrane‐modified electrode (MME). As a result, the fabricated biosensor has a linear detection range from 0.005 to 47 × 10^?3m (R = 0.9991) with a supralow detection limit of 0.56 × 10^?6m (S/N = 3). It is expected that this kind of nanofibrous MME has wider applications for the electrochemical detection and design of 3D functional nanomaterials in the future.     

Silver/Reduced Graphene Oxide Hydrogel as Novel Bactericidal Filter for Point‐of‐Use Water Disinfection

Nanomaterials open an alternative way for water disinfection. However, limitations such as aggregation, toxicity, and complex post‐treatment block their practical application. In this study, an antibacterial silver/reduced graphene oxide (Ag/rGO) hydrogel consisting of controlled porous rGO network and well‐dispersed Ag nanoparticle is synthesized by a facile hydrothermal reaction. Scanning electron microscopy, transmission electron microscope, X‐ray diffraction, mercury porosimetry, and Fourier transform IR spectroscopy are employed to characterize the Ag/rGO hydrogel. The 3D structure of the rGO network serves as an excellent support for Ag nanoparticles. Disinfection experiments show that the Ag/rGO hydrogel exhibits good efficacy against Escherichia coli when used as a bactericidal filter driven by gravity. The mechanistic study indicates that bacteria cells are inactivated due to cell membrane damage induced by silver nanoparticles and rGO nanosheets when they flow through Ag/rGO hydrogel. Moreover, due to the retaining of Ag by rGO, the leaching level of silver from Ag/rGO hydrogel is considerably lower than the drinking water standard. This study sheds new light on designing antibacterial materials for point‐of‐use water disinfection application.     

Graphene as an Electron Shuttle for Silver Deoxidation: Removing a Key Barrier to Plasmonics and Metamaterials for SERS in the Visible

The role of graphene in enabling deoxidation of silver nanostructures, thereby contributing to enhance plasmonic properties and to improve the temporal stability of graphene/silver hybrids for both general plasmonic and meta‐materials applications, as well as for surface enhanced Raman scattering (SERS) substrates, is demonstrated. The chemical mechanism occurring at the graphene–silver oxide interface is based on the reduction of silver oxide triggered by graphene that acts as a shuttle of electrons and as a kind of catalyst in the deoxidation. A mechanism is formulated, combining elements of electron transfer, role of defects in graphene, and electrochemical potentials of graphene, silver, and oxygen. Therefore, the formulated model represents a step forward from the simple view of graphene as barrier to oxygen diffusion proposed so far in literature. Single layer graphene grown by chemical vapor deposition is transferred onto silver thin films, a periodic silver fishnet structure fabricated by nanoimprint lithography, and onto silver nanoparticle ensembles supporting a localized surface plasmon resonance in the visible range. Through the study of these nanostructured graphene/Ag hybrids, the effectiveness of graphene in preventing and reducing oxidation of silver plasmonic structures, keeping silver in a metallic state over months at air exposure, is demonstrated. The enhanced and stable plasmonic properties of the silver‐fishnet/graphene hybrids are evaluated through their SERS response for detecting benzyl mercaptane.