碳纳米管@SiO_2@Ag纳米复合材料的制备及其表面增强拉曼效应

本文以SiO2为中间层,在多壁碳纳米管(MWCNTs)表面负载Ag纳米粒子,制备出CNTs@SiO2@Ag纳米复合材料,并采用TEM、XRD、UV-Vis、XPS等对纳米复合材料的结构、形貌和成分进行了表征,同时对该纳米复合材料的表面增强拉曼散射(Surface-enhanced Raman scattering,SERS)效应进行了研究。结果显示,Ag纳米颗粒有效提高了CNTs的SERS活性,纳米复合材料的拉曼峰强度是单纯CNTs拉曼峰强的近5倍。进一步研究了吸附罗丹明6G生物染料分子的SERS光谱,结果表明R6G分子的拉曼信号的质量与强度得到显著提高。因此,所制备的CNTs@SiO2@Ag纳米复合材料有望作为SERS的活性基底,应用于生物无损检测领域。     

Ag/Si-NPA基底上共吸附R6G和CV的表面增强拉曼散射

以硅纳米孔柱阵列(Si-NPA)为基底, 采用浸渍沉积技术制备了具有较高表面增强拉曼散射(SERS)活性的Ag/Si-NPA衬底, 并采用扫描电子显微镜和透射电子显微镜对其表面形貌和结构进行了表征. 在此基础上, 选择罗丹明6G(R6G)和结晶紫(CV)2种生物染料分子并采用不同的混合吸附程序对其共吸附状态下的SERS光谱进行了探测. 结果表明, 当2种分子的溶液浓度均为10^-7 mol/L时, 无论采用何种浸渍吸附程序, 其SERS谱中CV的特征拉曼峰都被R6G完全掩盖. 对溶液采用错级配置(R6G和CV的浓度分别为10^-9和10^-7 mol/L)后, 所测SERS谱上获得了分别对应于R6G和CV的分离良好、相对强度匹配、分辨率高的2个SERS特征峰组, 从而有利于简化现实混合探测过程中对SERS特征峰的指认和判断.     

帽状铜纳米粒子的制备及表面增强拉曼散射活性研究

采用真空热蒸发法在SiO₂纳米粒子自组装单层膜上沉积铜薄膜制备了帽状铜纳米粒子。用扫描电镜、原子力显微镜和紫外-可见-近红外分光光度计对帽状复合纳米粒子的表面形貌和光学性质进行了表征。以亚甲基蓝和吡啶-(2-偶氮-4)间苯二酚为探针分子,研究了该复合纳米粒子的表面增强拉曼散射(SERS)活性。通过比较吸附在不同基底上的吡啶-(2-偶氮-4)间苯二酚的谱峰强度,探讨了SERS效应与表面等离子体共振(SPR)的关系。     

有序Au/Ag纳米碗阵列的简易制备及其表面增强拉曼散射性能

通过湿法化学合成基于SiO₂胶体晶体的大面积有序Au/Ag纳米碗(Au/AgNB)阵列。首先,在玻璃基板上组装3D SiO₂胶体晶体作为模板。然后,以Au纳米颗粒(AuNP)为种子,通过原位生长法在SiO₂模板上沉积一层Au纳米壳(AuNS)。再通过HCHO还原Ag⁺成Ag⁰,进一步在AuNS表面沉积Ag纳米壳,形成Ag/Au双纳米壳(Ag/AuNS)阵列。最后通过丙烯酸酯改性双向取向聚丙烯(BOPP)膜方便地获得了单层有序反转Ag/AuNB阵列。这种有序Au/AgNB阵列具有更佳的表面增强拉曼散射(SERS)活性,其SERS分析增强因子(AEF)可达2.23×10⁷。     

黄曲霉素B2分子吸附在银团簇的表面增强拉曼散射机理

采用密度泛函理论（DFT）B3LYP方法,6-311G（d,p）（C,H,O）/LANL2DZ（Ag）基组,计算了黄曲霉素B₂（AFB₂）分子吸附在Ag₂团簇的表面增强拉曼散射（SERS）光谱和预共振拉曼光谱,并与实验结果比较. 结果显示：AFB₂分子在基态Ag₂团簇表面吸附时,增强因子最大达到10²,对应吡喃（pyrane）环C=O伸缩振动,主要是由AFB₂分子周围化学环境改变而引起的基态静极化率改变导致的化学增强. 不同激发波长下的AFB₂分子预共振拉曼光谱的增强强度不同：电荷转移态激发波长为1144 和544 nm时拉曼信号增强了10²倍,而选择电荷转移预共振波长432和410 nm作为入射光时,其拉曼信号增强了10⁴倍,增强机理为银团簇和黄曲霉素分子之间的电荷转移共振增强. 因此通过改变入射光波长,选择电荷转移共振激发波长,更有利于强致癌物AFB₂分子的痕量检测.     

Ag/ZIF-90自组装薄膜的制备及SERS活性研究

合成了金属有机框架化合物沸石咪唑框架-90(ZIF-90)溶胶和ZIF-90晶体薄膜,分别以这2种材料为基底,制备出了Ag@ZIF-90复合材料和Ag/ZIF-90自组装薄膜.通过傅里叶变换红外(FT-IR),X射线衍射(XRD),扫描电子显微镜(SEM)对产物进行表征,分析了它们的形貌和结构特征.以罗丹明6G(R 6G)作为检测分子,对所制备材料的表面增强拉曼散射(SERS)性能进行测试.结果表明制备出的Ag/ZIF-90自组装薄膜具有好的SERS性能,而ZIF-90本身的拉曼峰并不会对Ag/ZIF-90自组装薄膜的SERS检测效果产生影响.这种材料可以作为一种较好的表面增强拉曼(SERS)活性基底,在农药残留检测方面具有很好的应用前景.     

有序Au/Ag纳米碗阵列的简易制备及其表面增强拉曼散射性能

通过湿法化学合成基于SiO₂胶体晶体的大面积有序Au/Ag纳米碗(Au/AgNB)阵列。首先,在玻璃基板上以3D SiO₂胶体晶体作为模板。然后,在Au纳米颗粒(AuNP)种子的帮助下,通过原位生长方法在模板上沉积一层Au纳米壳(AuNS)。再通过HCHO还原Ag⁺使AuNS表面进一步沉积Ag纳米壳,形成Ag/Au双纳米壳(Ag/AuNS)阵列。通过丙烯酸酯改性双向取向聚丙烯(BOPP)方便地获得了单层有序反转Ag/AuNB阵列。这种有序Au/AgNB阵列具有更佳的表面增强拉曼散射(SERS)活性,其SERS分析增强因子(AEF)可达2.23×10⁷。     

磁性Ag@Fe3O4@C负载纳米金的制备及其SERS性能

利用一步溶剂热法制备了具有核壳结构的Ag@Fe₃O₄磁性纳米颗粒,然后以葡萄糖作为碳源对Ag@Fe₃O₄进行包覆,再利用酰胺化反应成功的将聚乙烯亚胺（PEI）修饰到Ag@Fe₃O₄@C表面,最后以N-Au共价键的方式将Au纳米粒子组装到Ag@Fe₃O₄@C表面。以4-巯基苯甲酸（4MBA）为拉曼活性探针分子来考察该复合纳米材料的表面增强拉曼（SERS）性能。通过控制Au纳米粒子的加入量,来调节Ag@Fe₃O₄@C-Au复合纳米材料的SERS活性。通过实验测试及利用时域有限差分法（FDTD）得出不同纳米金用量包覆的Ag@Fe₃O₄@C磁性纳米颗粒对4MBA的SERS效果依次为Ag@Fe₃O₄@C-Au-40 > Ag@Fe₃O₄@C-Au-10 > Ag@Fe₃O₄@C-Au-60 > Ag@Fe₃O₄@C,其中Ag@Fe₃O₄@C-Au-40的饱和磁化强度为411 A·g^-1,其对4MBA的检测限为1×10^-9 mol·L^-1。这种功能性复合材料既具有良好的SERS活性,又可通过外加磁场的方式实现对待测分子的分离、富集。     

TiN纳米管的制备及其作为SERS基底的应用

采用阳极氧化法在钛片表面制备TiO₂纳米管阵列,并经氨气氮化得到TiN纳米管阵列,通过XRD、SEM、XPS、UV-Vis对基底的组成、形貌和光学性能进行了表征,并以罗丹明6G（R6G）为探针分子,对TiN基底的SERS活性进行检测。结果显示,TiO₂纳米管经800℃以上高温可转化为TiN纳米管,纳米管直径在100~200 nm,排列规整有序。氮化后的样品在500~600 nm处出现TiN的等离子体共振吸收峰,该基底显示出较高的SERS活性,对R6G分子的检测极限可达~10^-7 mol·L^-1,增强因子达~10⁵。     

圆形片状纳米复合材料Ag/ZnO-ZrO2微波辅助合成与多模式光催化罗丹明B

采用微波辅助结合沉淀法制备了以ZnO为主体的纳米复合材料Ag/ZnO-ZrO₂。通过X射线粉末衍射(XRD)、紫外-可见漫反射吸收光谱(UV-Vis/DRS)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和N2吸附-脱附等表征手段研究了微波辐射对Ag/ZnO-ZrO₂晶型结构、形貌及表面物理化学性质的影响。结果表明, 在200 W微波辐射作用下, 该样品晶型结构未发生明显变化, 但Ag的衍射峰明显增强, 同时, 其晶粒尺寸、光吸收性质和表面物理化学性质等方面则发生改变, 尤其是样品Ag/ZnO-ZrO₂的形貌呈现了圆形片状结构。分别在紫外和微波辅助条件下对纳米复合材料的光催化性能进行了一系列考察, 同时为了进一步评价所合成样品在太阳光作用下的实用价值, 又考察了Ag/ZnO-ZrO₂在模拟日光条件下的光催化性能。结果显示, 紫外光作用下, 纳米复合材料Ag/ZnO-ZrO₂的光催化活性高于市售P25以及未经微波处理的样品, 且在微波辅助光催化条件下, 其活性有较大程度提高。200 W微波功率下所合成样品Ag/ZnO-ZrO₂在模拟日光作用下显现出较高活性。另外, 根据紫外光条件下对光催化活性物种的捕获实验提出了Ag/ZnO-ZrO₂可能的光催化机理。     

可循环SERS基底ZnO/Ag纳米材料合成和表征

利用简易、绿色、一锅煮的水热法合成了花状氧化锌/银复合纳米材料。然后利用各种光谱和显微技术对复合物进行了表征,并讨论了其表面增强拉曼(SERS)性能和光催化性能。结果表明氢氧化钠的量对于这种复合纳米材料的形貌和性能具有重要的调节作用。和其他形貌的氧化锌/银复合纳米材料相比较,花状氧化锌/银复合纳米材料具有最佳的光催化性能。同时进一步以花状氧化锌/银复合纳米材料作为SERS基底研究其表面增强拉曼性能,结果表明这种复合材料同时具有很好的表面增强拉曼性能。光催化和表面增强拉曼结果表明这种花状氧化锌/银复合纳米材料有望在有机物检测中作为一种具有很好的可循环性的新表面增强拉曼基底材料。     

可循环SERS基底ZnO/Ag纳米材料合成和表征

利用简易、绿色、一锅煮的水热法合成了花状氧化锌/银复合纳米材料。然后利用各种光谱和显微技术对复合物进行了表征,并讨论了其表面增强拉曼（SERS）性能和光催化性能。结果表明氢氧化钠的量对于这种复合纳米材料的形貌和性能具有重要的调节作用。和其他形貌的氧化锌/银复合纳米材料相比较,花状氧化锌/银复合纳米材料具有最佳的光催化性能。同时进一步以花状氧化锌/银复合纳米材料作为SERS基底研究其表面增强拉曼性能,结果表明这种复合材料同时具有很好的表面增强拉曼性能。光催化和表面增强拉曼结果表明这种花状氧化锌/银复合纳米材料有望在有机物检测中作为一种具有很好的可循环性的新表面增强拉曼基底材料。     

Synthesis of Cu2O/Ag Composite with Visible Light Photocatalytic Degradation Activity for in situ SERS Analysis

A multifunctional Cu₂O/Ag micro-nanocomposite, which has the characteristics of high catalytic activities under the visible light and high surface-enhanced Raman scattering (SERS) activity, was fabricated via a facile method and employed for the in situ SERS monitoring of the photocatalytic degradation reaction of crystal violet. Through the variation of the AgNO₃ concentration, Ag content on the Cu₂O template can be controllably tuned, which has great influence on the SERS effect. The results indicate that Ag nanoparticles form on the Cu₂O nanoframes to obtain the Cu₂O/Ag nanocomposite, which can act as an excellent bifunctional platform for in situ monitoring of photocatalytic degradation of organic pollutions by SERS.     

二步电沉积法制备Au/氧化石墨烯复合薄膜作为SERS基底

采用二步电沉积方法在Ti片表面制备了Au-氧化石墨烯（Au-GO）复合薄膜,通过XRD、SEM、XPS等对薄膜的组成、结构和形貌进行了表征,并以罗丹明6G（R6G）为探针分子,对Au-GO/Ti基底的SERS活性进行了表征。结果显示,Au纳米颗粒尺寸约为60 nm,均匀、致密分布于GO表面,该基底显示出较高的SERS活性,对R6G分子的检测极限可达~10^-10 mol·L^-1,增强因子高达约10⁶,且基底显示出良好的稳定性,在冰箱中存放90 d后,SERS活性仅降低30%左右。     

二步电沉积法制备Au/氧化石墨烯复合薄膜作为SERS基底

采用二步电沉积方法在Ti片表面制备了Au-氧化石墨烯（Au-GO）复合薄膜,通过XRD、SEM、XPS等对薄膜的组成、结构和形貌进行了表征,并以罗丹明6G（R6G）为探针分子,对Au-GO/Ti基底的SERS活性进行了表征。结果显示,Au纳米颗粒尺寸约为60 nm,均匀、致密分布于GO表面,该基底显示出较高的SERS活性,对R6G分子的检测极限可达~10^-10 mol·L^-1,增强因子高达约10⁶,且基底显示出良好的稳定性,在冰箱中存放90 d后,SERS活性仅降低30%左右。     

Silver overlayer-modified surface-enhanced Raman scattering-active gold substrates for potential applications in trace detection of biochemical species

Because Ag and Au nanoparticles (NPs) possess well-defined localized surface plasmon resonance (LSPR) they are popularly employed in the studies of surface-enhanced Raman scattering (SERS). As shown in the literature and in our previous studies, the advantage of SERS-active Ag NPs is their higher SERS enhancement over Au NPs. On the other hand, the disadvantage of SERS-active Ag NPs compared to Au NPs is their serious decay of SERS enhancement in ambient laboratory air. In this work, we develop a new strategy for preparing highly SERS-active Ag NPs deposited on a roughened Au substrate. This strategy is derived from the modification of electrochemical underpotential deposition (UPD) of metals. The coverage of Ag NPs on the roughened Au substrate can be as high as 0.95. Experimental results indicate that the SERS of Rhodamine 6G (R6G) observed on this developed substrate exhibits a higher intensity by ca. 50-fold of magnitude, as compared with that of R6G observed on the substrate without the deposition of Ag NPs. The limit of detection (LOD) for R6G measured on this substrate is markedly reduced to 2 × 10⁻¹⁵ M. Moreover, aging of SERS effect observed on this developed substrate is significantly depressed, as compared with that observed on a generally prepared SERS-active Ag substrate. These aging tests were performed in an atmosphere of 50% relative humidity (RH) and 20% (v/v) O₂ at 30 °C for 60 day. Also, the developed SERS-active substrate enables it practically applicable in the trace detection of monosodium urate (MSU)-containing solution in gouty arthritis without a further purification process.     

ZnGa2O4 Nanorod Arrays Decorated with Ag Nanoparticles as Surface‐Enhanced Raman‐Scattering Substrates for Melamine Detection

The availability of sensitive, reproducible, and stable substrates is critically important for surface‐enhanced Raman spectroscopy (SERS)‐based applications, but it presently remains a challenge. In this work, well‐aligned zinc gallate (ZnGa₂O₄) nanorod arrays grown on a Si substrate by chemical vapor deposition were used as templates to fabricate SERS substrates by deposition of Ag nanoparticles onto the ZnGa₂O₄ nanorod surfaces. The coverage of the Ag nanoparticles on the ZnGa₂O₄ nanorod surfaces was easily controlled by varying the amount of AgNO₃. SERS measurements showed that the number density of Ag nanoparticles on the ZnGa₂O₄ nanorod surfaces had a great effect on SERS activity. The SERS signals collected by point‐to‐point and SERS mapping images showed that as‐prepared SERS substrates exhibited good spatial uniformity and reproducibility. Detection of melamine molecules at low concentrations (1.0×10^?7 M ) was used as an example to show the possible application of such a substrate. In addition, the effect of benzoic acid on the detection of melamine was also investigated. It was found that the SERS signal intensity of melamine decreased greatly as the concentration of benzoic acid was increased.     

Silver Nanostructures on Graphene Oxide as the Substrate for Surface-Enhanced Raman Scattering (SERS)

Nanosized surface-enhanced Raman scattering (SERS) substrates fabricated by the controlled growth of metal nanostructures on water-dispersed two-dimensional nanomaterials can open a new avenue for SERS analysis of liquid samples in biological fields. In this work, regular and uniform Ag nanostructures were grown on the surface of graphene oxide (GO) through a microwave-assisted hydrothermal method. Polyamidoamine (PAMAM) dendrimers were assembled on the surface of GO to form GO/PAMAM templates for growing Ag nanostructures, which are primarily comprised of Ag dimers and trimers. The prepared Ag/GO nanocomposites are highly dispersed and stable in aqueous solution and may be used as substrates for enhanced Raman detection of rhodamine 6?G (R6G) in aqueous solution. This special substrate provides high-performance SERS and suppresses R6G fluorescence in aqueous solution and is promising as a nanosized material for the enhanced Raman detection of liquid samples in biological diagnostics.     

Improved surface-enhanced Raman scattering on electrochemically roughened silver substrates prepared in bielectrolyte solutions

In this work, the effect of supplemental LiClO₄ electrolytes in KCl solutions used in roughening silver substrates by electrochemical triangular-wave oxidation-reduction cycles (ORC) on surface-enhanced Raman scattering (SERS) was first investigated. To prepare SERS-active substrates by ORC procedures, electrolytes of KCl were generally employed. In contrast, LiClO₄ ones were unsuitable for producing SERS-active substrates. Encouragingly, SERS of Rhodamine 6G (R6G) adsorbed on the roughened Ag substrate prepared in an aqueous solution containing KCl and LiClO₄ electrolytes exhibits a higher intensity by one order of magnitude, as compared with that of R6G adsorbed on a roughened Ag substrate prepared in a solution only containing KCl. Further investigations indicate that the oxidation state of Cl on the roughened Ag substrate demonstrates decided effects on this improved SERS.