Application of Monodisperse Thermo-Responsive Composite Microgels with Core-Shell Structure Based on Au@Ag Bimetallic Nanorod as Core in Surface Enhanced Raman Spectroscopy Substrate

The monodisperse Au@Ag bimetallic nanorod is encapsulated by crosslinked poly( N-isopropylacrylamide)( PNIPAM) to produce thermo-responsive composite microgel with well-defined core-shell structure( Au@ Ag NR@ PNIPAM microgel)by seed-precipitation polymerization method using butenoic acid modified Au @ Ag NRs as seeds. When the temperature of the aqueous medium increases from 20℃ to 50℃,the localized surface plasmon resonance( LSPR) band of the entrapped Au @ Ag NR is pronouncedly red-shifted because of the decreased spatial distances between them as a result of shrinkage of the microgels,leading to their plasmonic coupling. The temperature tunable plasmonic coupling is demonstrated by temperature dependence of the surface enhanced Raman spectroscopy( SERS) signal of 1-naphthol in aqueous solution. Different from static plasmonic coupling modes from nanostructured assembly or array system of noble metals,the proposed plasmonic coupling can be dynamically controlled by environmental temperature. Therefore, the thermo responsive hybrid microgels have potential applications in mobile LSPR or SERS microsensors for living tissues or cells.

Synthesis of novel MnO_x@TiO_2 core-shell nanorod catalyst for low-temperature NH_3-selective catalytic reduction of NOx with enhanced SO_2 tolerance

In this study,a MnOx@TiO2 core‐shell catalyst prepared by a two‐step method was used for the low‐temperature selective catalytic reduction of NOx with NH3.The catalyst exhibits high activity,high stability,and excellent N2 selectivity.Furthermore,it displays better SO2 and H2O tolerance than its MnOx,TiO2,and MnOx/TiO2 counterparts.The prepared catalyst was characterized systematically by transmission electron microscopy,high‐resolution transmission electron microscopy,X‐ray diffraction,Raman,BET,X‐ray photoelectron spectroscopy,NH3 temperature‐programmed desorption and H2 temperature‐programmed reduction analyses.The optimized MnOx@TiO2 catalyst exhibits an obvious core‐shell structure,where the TiO2 shell is evenly distributed over the MnOx nanorod core.The catalyst also presents abundant mesopores,Lewis‐acid sites,and high redox capability,all of which enhance its catalytic performance.According to the XPS results,the decrease in the number of Mn4+active centers after SO2 poisoning is significantly lower in MnOx@TiO2 than in MnOx/TiO2.The core‐shell structure is hence able to protect the catalytic active sites from H2O and SO2 poisoning.

Growth of Carbon Encapsulated Long Nickel Nanorods on Bulk Nickel Substrate

Carbon nanotube encapsulated nickel nanorods were catalytic grown via pyrolysis of oil on a bulk nickel wire substrate. X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy and Raman spectroscopy were employed to characterize the as-prepared sample. The results show that, carbon nanotubes possess several microns in length, the filled metallic nickel nanorods with a uniform diameter of 35 nm were tightly encapsulated by the carbon capsules. The detailed formation mechanism for the carbon nanotubes encapsulated nickel nanorods were discussed briefly.

Gold Nanorods: Near-Infrared Plasmonic Photothermal Conversion and Surface Coating

In this paper, AuNRs colloids with SPRL located at ~810 nm and ~1100 nm were synthesized using an improved seed method. Based on the NIR lasers available, photothermal conversion of AuNRs were systematically studied compared with that of water. Under low power irradiation, the highest temperature is obtained when the SPRL wavelength of AuNRs is equal to the laser wavelength, and temperature of colloid increases from ~20°C to ~65°C. With increasing laser power (such as 6 W), the AuNRs colloid boils within a few minutes, and nanorods undergo a shape deformation from rod to spherical particle and even fusion, and the SPRL disappears. For further investigation, the obtained AuNRs were coated with SiO2 shell to form a core-shell nanostructure (Au@SiO2). The surface coating can be used not only in keeping the stability of AuNRs for further treatment, but also in increasing plasmonic property and biocompatibility. This work will be useful for designing plasmonic photothermal properties and further applications in nanomedicine.

A 3D hierarchical electrocatalyst:Core–shell Cu@Cu(OH)_(2)nanorods/MOF octahedra supported on N-doped carbon for oxygen evolution reaction

Cu-based materials are seldom reported as oxygen evolution reaction(OER)electrocatalysts due to their inherent electron orbital configuration,which makes them difficult to adsorb oxygen-intermediates during OER.Reasonably engineering the hierarchical architectures and the electronic structures can improve the performance of Cu-based OER catalysts,such as constructing multilevel morphology,inducing the porous materials,improving the Cu valence,building heterostructures,doping heteroatoms,etc.In this work,copper-1,3,5-benzenetricarboxylate(HKUST-1)octahedra in-situ grow on the Cu nanorod(NR)-supported N-doped carbon microplates,meanwhile an active layer of Cu(OH)_(2)forms on the surface of the original conductive Cu NRs.The octahedral HKUST-1,serving as a spacer between the microplates,greatly improves the porosity and increases the available active sites,facilitating the mass transport and electron transfer,thus resulting in greatly enhanced OER performance.

Cu^(2+)-Assisted Synthesis of Au@AgI Core/Shell Nanorods via In Situ Oxidation of Iodide:A Strategy for Colorimetric Iodide Sensing

Colorimetric nanoprobes are frequently employed to construct sensitive sensors via various strategies.In this work,a novel strategy for simple and ultrasensitive sensing of iodide(I_(−))was constructed based on Cu^(2+)-assisted generation of Au@AgI core/shell nanorods(NRs),by etching silver-coated gold nanorods(Ag@Au NRs).Ag@Au NRs were first prepared and characterized with UV-visible spectroscopy,transmission electron microscopy,high-angle annular dark-field scanning transmission electron microscopy,and energy-dispersive X-ray spectroscopy before and after iodide treatment.The mechanism of detection was based on the generation of AgI shells via etching Ag shells by I_(2),which was produced from the oxidation of I_(−)with Cu^(2+),resulting in the peak shift of localized surface plasmon resonance(LSPR)while the color changed from green,blue to light-violet.The red-shift of the longitudinal LSPR peak had a linear relationship with I_(−)concentration in the range of 0-50μmol/L with a correlation coefficient of 0.982.Furthermore,the proposed method was used for the quantitative detection of I_(−)in real samples and outstanding recoveries in the range of 91-106%with relative standard deviations lower than 2.5%were observed.

载Au@Ag核壳复合双金属纳米棒的复合滤纸用作SERS基底

通过静电相互作用将单分散性良好的Au@Ag核壳复合双金属纳米棒(Au@AgNRs)负载于滤纸,制得载Au@AgNRs的复合滤纸。用扫描电子显微镜观察了使用不同Au@AgNRs溶液制备的复合滤纸Au@AgNRs中的分布情况,并统计了单位面积滤纸中Au@AgNRs的粒子数。将制得的载不同数量Au@AgNRs复合滤纸用作表面增强拉曼光谱(SERS)基底,通过擦拭载玻片检测了其表面吸附的微量二硫化四甲基秋兰姆,发现使用150nmol·L^(-1)Au@AgNRs溶液制备的复合滤纸具有较好的增强效果和检测重复性,十次重复检测结果的相对标准偏差为3.1%,检测线性范围为10^(-14)~10^(-7)mol·L^(-1)。载Au@AgNRs复合滤纸可作为SERS基底用于蔬菜水果表面农残的检测。

Synthesis of gold/rare-earth-vanadate core/shell nanorods for integrating plasmon resonance and fluorescence

The nanoscale core/shell heterostructure is a particularly efficient motif to combine the promising properties of plasmonic materials and rare-earth compounds; however, there remain significant challenges in the synthetic control due to the large interfacial energy between these two intrinsically unmatched materials. Herein, we report a synthetic route to grow rare-earth-vanadate shells on gold nanorod （AuNR） cores. After modifying the AuNR surface with oleate through a surfactant exchange, well-packaged rare-earth oxide （e.g., Gd2O3：Eu） shells are grown on AuNRs as a result of the multiple roles of oleate. Furthermore, the composition of the shell has been altered from oxide to vanadate （GdVO4：Eu） using an anion exchange method. Owing to the carefully designed strategy, the AuNR cores maintain the morphology during the synthesis process; thus, the final Au/GdVO4： Eu core/shell NRs exhibit strong absorption bands and high photothermal efficiency. In addition, the Au/GdVO4：Eu NRs exhibit bright Eu^3＋ fluorescence with quantum yield as high as -17%; bright Sm^3＋ and Dy^3＋ fluorescence can also be obtained by changing the lanthanide doping in the oxide formation. Owing to the attractive integration of the plasmonic and fluorescence properties, such core/shell heterostructures will find particular applications in a wide array of areas, from biomedicine to energy.

Sonochemical synthesis and photoluminescence properties of rare-earth phosphate core/shell nanorods

Rare earth phosphate core/shell nanostructures were synthesized via facile ultrasound irradiation method.XRD and TEM were em-ployed to characterize the structure and morphology properties.The photoluminescence(PL) properties of TbPO4/CePO4 and CePO4/TbPO4 core/shell nanorods were studied to explore the energy transfers from Ce3+ to Tb3+.In the Ce0.9Tb0.1PO4/LaPO4 core/shell nanorods,the PL intensity of Ce0.9Tb0.1PO4 nanorods was enhanced when the LaPO4 shells were coated.

Optical properties of＇ Au-core Pt-shell nanorods studied using FDTD simulations

Au-core/Pt-shell nanorods （Au@Pt NRs） have been prepared by a Au nanorod-mediated growth method, and they exhibit high electromagnetic field enhancements under coupling conditions. Boosted by a long-range effect of the high electromagnetic field generated by the Au core, the electromagnetic field enhancement can be controlled by changing the morphology of the nanostruc- tures. In this study, we report the results on the simulations of the electromagnetic field enhancement using a finite difference time domain （FDTD） method, taking the real shapes of the Au@Pt NRs into account. Due to the ＂hot spot＂ effect, the electromagnetic field can be localized between the Pt nanodots. The electromagnetic field enhancement is found to be rather independent of the Pt con- tent, whereas the local roughness and small sharp features might significantly modify the near-field. As the electromagnetic field enhancement can be tuned by the distribution of Pt nanodots over the Au-core, Au@Pt NRs can find potential applications in related areas.

无定型二氧化硅包裹的Au纳米棒(Au_(nanorod)@mSiO_2)的合成条件优化

目的合成Au纳米棒,并以Au纳米棒为核心,合成复合纳米结构(Au_(nanorod)@mSiO_2)并优化合成条件。方法首先采用种子生长法制备Au纳米棒,合成的长径比为4.8;将正硅酸乙酯在碱性条件下进行水解,在常温下,调节pH值在9~10之间,低速搅拌的条件下,借助于自组装技术,在Au纳米棒表面可形成不同厚度二氧化硅层。利用透射电镜(TEM)、X射线衍射(XRD)和紫外吸收光谱表征复合纳米粒子。结果所合成的纳米粒子经TEM表征,展示了层次分明的核壳结构,Au作为核心,二氧化硅层作为壳层。XRD表明复合结构中存在Au的衍射峰与二氧化硅的衍射峰。通过紫外吸收光谱表明,随着二氧化硅层厚度的增加,吸收峰发生红移现象。结论在优化条件下可合成不同二氧化硅层厚度的复合纳米粒子Au_(nanorod)@mSiO_2。

Advanced microemulsion synthesis and characterization of wollastonite （CaSiO3）fpolystyrene one-dimensional nanorods with core-shell structures

In this work, one-dimensional core-shell nanorods （CSNRs; 185-250nm wide and 1-1.5μm long） consisting of triethoxyvinylsilane-modified wollastonite （CaSiO3） nanorods （MWNRs） as a core and polystyrene as a shell with uniform size were successfully synthesized using an advanced microemulsion technique. The effect of varying the surfactant cetyltrimethylammonium bromide （producing CSNRSCTAB） or sodium dodecyl sulphate （producing CSNRSSDS） upon the size and morphology of the CSNRs was investigated by field-emission scanning electron microscopy （FE-SEM）. X-ray diffractometry and Fourier transform infrared spectrophotometer revealed the existence of a strong interaction between the MWNRs and polystyrene, which implies that the polymer chains were successfully grafted onto the surface of the MWNRs. The CSNRs were blended with polypropylene by melt processing, and the effect of the CSNRs upon the morphological properties of the polypropylene matrix was investigated by FE-SEM and atomic force microscopy. It was observed that the polystyrene chains that grafted onto the CaSiO3 nanorods interfered with the aggregation of CaSiO3 nanorods in the polypropylene matrix and thus improved the compatibility of the CaSiO3 nanorods with the polypropylene matrix. Furthermore, the compatibility of CaSiO3 nanorods with polypropylene of CSNRsDs/polypropylene was superior to that of CSNRCTAB/polypropylene.

核-壳结构ZnO@CuO光阳极的制备及其光电性能研究

ZnO是钙钛矿太阳电池(PSCs)电子传输层(ETL)的优良材料,但ZnO与钙钛矿吸收层界面有很大的热不稳定性,从而导致该界面严重的电荷复合。文章采用水热法在FTO导电玻璃上制备出具有良好取向性的ZnO纳米棒阵列(NAs)。通过调控电化学沉积时间,在ZnO NAs上沉积一层CuO纳米颗粒,获得ZnO@CuO纳米复合材料薄膜。利用场发射扫描电镜(FESEM)、X射线衍射(XRD)对复合薄膜的形貌和物相进行了观察和分析。通过紫外-可见光漫反射(UV-Vis DRS)和瞬态荧光光谱(PL)对其光学性能进行了测定。结果表明,制备的ZnO NAs阵列均匀且垂直度较好,直径约为120 nm;通过电化学沉积CuO纳米颗粒(尺寸为34~44 nm)后,复合薄膜的可见光吸收能力增强,载流子分离效率提高;在电化学沉积时间为40 s时,所得到的ZnO@CuO NAs的光电流密度最高,约为ZnO NAs的3.37倍,表现出良好的光电转换性能。

Vacuum-tuned-atmosphere induced assembly of Au@Ag core/shell nanocubes into multi-dimensional superstructures and the ultrasensitive IAPP proteins SERS detection

Utilizing vacuum-tuned-atmosphere induced dip coating method,we achieve the cross-dimensional macroscopic diverse self-assemblies by using one building block with one chemical functionality.Coordinated modulating the vacuum degree,colloid concentration and evaporation atmosphere,Au@Ag core/shell nanocubes (NCs) can controllably assemble into diverse multi-dimensional superstructures.Under 0.08 MPa,we obtained the two-dimensional (2D) stepped superstructures with continuously tunable step width.In addition,we generated a series of tailorable nanoscale-roughened 2D Au@Ag NCs superstructures at 0.04 MPa,which exhibited the label-free ultrasensitive SERS detection for the different mutants of IAPP8-37 proteins.Under 0.01 MPa,we obtained the cross-dimensional tailorable Au@Ag NCs assemblies from random to macroscale 2D and three-dimensional (3D) densest superstructures by adjusting the capping ligand-environmental molecule interactions.This is a flexible method to generate as-prepared Au@Ag core/shell NCs into well-defined macroscopic diverse superstructures and to promote the exploitation into biological applications.

Outer delocalized electron aggregation of bromide bridged core–shell CuBr@C for hydrogen evolution reaction

Modulation of the surface electron distribution is a challenging problem that determines the adsorption ability of catalytic process.Here,we address this challenge by bridging the inner and outer layers of the core–shell structure through the bridge Br atom.Carbon shell wrapped copper bromide nanorods(CuBr@C)are constructed for the first time by chemical vapour deposition with hexabromobenzene(HBB).HBB pyrolysis provides both bridge Br atom and C shells.The C shell protects the stability of the internal halide structure,while the bridge Br atom triggers the rearrangement of the surface electrons and exhibits excellent electrocatalytic activity.Impressively,the hydrogen evolution reaction(HER)activity of CuBr@C is significantly better than that of commercial N-doped carbon nanotubes,surpassing commercial Pt/C at over 200 mA·cm^(−2).Density functional theory(DFT)calculations reveal that bridge Br atoms inspire aggregation of delocalized electrons on C-shell surfaces,leading to optimization of hydrogen adsorption energy.

ZnO/Nb2O5 core/shell nanorod array photoanode for dye-sensitized solar cells

In this paper, ZnO/Nb2O5 core/shell nanorod arrays were synthesized and used as photoanodes for dye- sensitized solar cells （DSSCs）. We first synthesized ZnO nanorod array on fluorine-doped tin oxide （FTO） glasses by a hydrothermal method, and then ZnO/Nb2O5 core/shell nanorod array was directly obtained via solvothermal reaction in NbCl5 solution. The scanning electron micro- scope （SEM） and transmission electron microscope （TEM） images revealed that the ZnO nanorods were uniformly wrapped by Nb2O5 shell layers with a thickness of 30-40 nm. Photovoltaic characterization showed that the device based on ZnO/Nb2O5 core/shell nanorod photoanode exhibited an improved efficiency of 1.995%, which was much higher than the efficiency of 0.856% for the DSSC based on bare ZnO nanorod photoanode. This proved that the photovoltaic performance of ZnO nanorods could be improved by wrapping with Nb2O5 shells.

Ultra-stable silica-coated chiral Au-nanorod assemblies： Core-shell nanostructures with enhanced chiroptical properties

Chiral nano-assemblies with amplified optical activity have attracted particular interest for their potential application in photonics, sensing and catalysis. Yet it still remains a great challenge to realize their real applications because of the instability of these assembled nanostructures. Herein, we demonstrate a facile and efficient method to fabricate ultra-stable chiral nanostructures with strong chiroptical properties. In these novel chiral nanostructures, side-by-side assembly of chiral cysteine-modified gold nanorods serves as the core while mesoporous silica acts as the shell. The chiral core-shell nanostructures exhibit an evident plasmonic circular dichroism （CD） response originating from the chiral core. Impressively, such plasmonic CD signals can be easily manipulated by changing the number as well as the aspect ratio of Au nanorods in the assemblies located at the core. In addition, because of the stabilization effect of silica shells, the chiroptical performance of these core-shell nanostructures is significantly improved in different chemical environments.

Synthesis of core-shell structured Au@Bi2S3 nanorod and its application as DNA immobilization matrix for electrochemical biosensor construction

The core-shell structured Au@Bi2S3 nanorods have been prepared through direct in-situ growth of Bi2S3 at the surface of pre-synthesized gold nanorods.The product was characterized by X-ray diffraction,transmission electron microscopy and energy-dispersive X-ray spectroscopy.Then the obtained Au@Bi2S3 nanorods were coated onto glassy carbon electrode to act as a scaffold for fabrication of electrochemical DNA biosensor on the basis of the coordination of-NH2 modified on 5’-end of probe DNA and Au@Bi2S3.Electrochemical characterization assays demonstrate that the Au@Bi2S3 nanorods behave as an excellent electronic transport channel to promote the electron transfer kinetics and increase the effective surface area by their nanosize effect.The hybridization experiments reveal that the Au@Bi2S3 matrix-based DNA biosensor is capable of recognizing complementary DNA over a wide concentration ranging from 10 fmol/L to 1 nmol/L.The limit of detection was estimated to be 2 fmol/L(S/N=3).The biosensor also presents remarkable selectivity to distinguish fully complementa ry sequences from basemismatched and non-complementary ones,showing great promising in practical application.

CdS/SiO_2纳米棒核/壳结构的制备和发光性能

利用在醇介质中氨水催化水解硅酸乙酯(TEOS)制备SiO2来包覆半导体CdS纳米棒而形成CdS/SiO2核/壳结构.通过X射线衍射(XRD)、透射电子显微镜(TEM)证实SiO2包覆壳层为非晶,且壳层厚度随TEOS浓度的增大而增加,在10～30nm之间.并研究了其紫外-可见吸收光谱(UV-Vis)和荧光发射光谱(PL)的性质.

多孔核壳结构Ni@C纳米棒的制备及其对高氯酸铵热分解催化性能的影响

为了提高纳米金属对高氯酸铵(AP)热分解的催化作用,采用溶剂热法与高温煅烧法,以镍基有机金属骨架(Ni-MOF)为前驱体制备了Ni@C纳米棒。利用X射线衍射仪、场发射扫描电子显微镜、高倍透射电子显微镜、X射线光电子能谱仪、拉曼光谱仪、全自动物理吸附分析仪等表征了Ni@C纳米棒的形貌、结构及组成,并通过差示扫描量热仪研究了不同煅烧温度下Ni@C纳米棒对AP热分解的催化效果。结果表明,Ni@C纳米棒为以金属Ni为核、C层为壳的多孔核壳结构,且高度石墨化的C层有效防止了纳米Ni颗粒的氧化。Ni@C纳米棒对AP热分解的催化性能优于单独镍纳米颗粒和碳纳米棒。尤其是1000℃煅烧后的Ni@C纳米棒使AP的高温分解峰峰温从423.4℃降低至323.8℃,表观分解热从825.4J·g^-1提高到1423.8J·g^-1,反应活化能从172.50kJ·mol^-1降低至130.04kJ·mol^-1。