Nanomaterials
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2018
·Vol. 8
·期 6
·376
·
IF 3.504
Luhang Xu,Dengpo Huang,Huimei Chen,Xiaoling Jing,Jiale Huang,Tareque Odoom-Wubah,Qingbiao Li
Synthesis and applications of one dimensional (1D) metal nanostructures have attracted much attention. However, one-step synthesis of bimetallic nanowires (NWs) has remained challenging. In this work, we developed a microorganism-mediated, hexadecyltrimethylammonium bromide (CTAB)-directed (MCD) approach to synthesize closely packed and long Au-Ag NWs with the assistance of a continuous injection pump. Characterization results confirmed that the branched Au-Ag alloy NWs was polycrystalline. And the Au-Ag NWs exhibited a strong absorbance at around 1950 nm in the near-infrared (NIR) region, which can find potential application in NIR absorption. In addition, the Au-Ag NWs showed excellent surface-enhanced Raman scattering (SERS) enhancement when 4-mercaptobenzoic acid (MBA) and rhodamine 6G (R6G) were used as probe molecules.Keywords:microorganism-mediated;Au-Ag NWs;SERS enhancement;Pichia pastoriscells;CTAB
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Nano Research
·
2018
·Vol. 12
·期 2
·449-455
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IF 7.994
Huang Zhulin,Meng Guowen,Hu Xiaoye,Pan Qijun,Huo Dexian,Zhou Hongjian,Ke Yan,Wu Nianqiang
A facile synthetic approach has been developed to prepare uniform and size-tunable spiky Au@Ag core-shell nanoparticles (NPs) to tailor the localized surface plasmon resonance (LSPR) properties. The gradual assembly of small Au nanocrystals allows the size of spiky Au NPs to be modulated from tens to several hundreds of nanometers by tuning the concentration of initial Au seeds and Au source; and the thickness of the Ag shell can be adjusted with stepwise reduction of Ag(I) ions. The LSPR bands of such spiky Au@Ag core-shell NPs resemble those of pure spiky Au NP cores of similar sizes in near-infrared region, and increasing the Ag shell thickness results in a blue shift and broadening of the LSPR band in the near-infrared region. Additionally, the spiky Au@Ag core-shell NPs exhibit improved surface-enhanced Raman scattering (SERS) activity as compared to the bare spiky Au NPs and spherical Ag@Au NPs. This work has offered a facile route to synthesize plasmonic metal NPs with LSPR band in 650 to 800 nm that show strong enhancement of localized electromagnetic field, which provides an effective SERS substrate for SERS imaging and detection in biological fluids and tissues.
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GREEN CHEMISTRY
·
2019
·Vol. 21
·期 11
·3081-3090
·
IF 9.405
Lin Dong,Yu Xin,Xiaohui Liu,Yong Guo,Chih-Wen Pao,Jeng-Lung Chen,Yanqin Wang
Transformation of lignin into high value-added phenolics is of great significance but extremely challenging. Herein, we report a single-step process for the preparation of phenolics from both 2-methoxy-4-propylphenol (one of the major products derived from lignin) and lignin oil (lignin-derived monomers) over Au-based catalysts. In this process, the desired Ar–OH substituents can be maintained and phenolics can be obtained with high yields. The performance of the Au/Nb2O5 catalyst is compared with those of Au/TiO2, Au/Al2O3 and Au/ZrO2 and it is shown that Au/Nb2O5 has high activity, excellent stability and remarkable selectivity to phenolics, with the yields of phenolics reaching 84.2% for 2-methoxy-4-propylphenol and 66.7 wt% for lignin oil. The detailed studies reveal that the hydrodeoxygenation of 2-methoxy-4-propylphenol undergoes two-steps, i.e., hydrolysis to propylcatechol catalyzed by the acid sites of supports, and the hydrogenolysis of propylcatechol to propylphenol realized by the synergistic effect between Au and the supports. It is found that the high hydrodeoxygenation activity of Au/Nb2O5 depends on both the electron-rich Au nanoparticles and the Nb2O5 support with the efficient cleavage of the Caromatic–O linkage. This study provides a new catalytic system towards highly efficient and selective conversion of lignin oils to valuable phenolics.
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LANGMUIR
·
2018
·
IF 3.789
Jianfeng Zhang,Qunling Fang,Jinyu Duan,Hongmei Xu,Huajian Xu,Shouhu Xuan
This work reports a novel Fe3O4@polydopamine/Au/polydopamine core/shell nanocomposite toward a magnetically separable nanocatalyst. Because the polydopamine (PDA) layer-sandwiched Au nanocrystals were prepared by a layer-by-layer method, the content of Au could be controlled by varying the Au shell number (such as burger-like Fe3O4@PDA/Au/PDA/Au/PDA). Fe3O4@PDA/Au/PDA exhibited excellent catalytic activity in reducing p-nitrophenol because the substrate could penetrate the PDA shell. Owing to the protection of the PDA shell, Fe3O4@PDA/Au/PDA presented higher cyclability than Fe3O4@PDA/Au. The activity of Fe3O4@PDA/Au/PDA maintained 95% after 7 cycles, while that of Fe3O4@PDA/Au was only 61%. The detailed cycling catalytic mechanism was investigated, and it was found that the catalytic rate of Fe3O4@PDA/Au/PDA/Au/PDA was faster than that of Fe3O4@PDA/Au/PDA because of the higher Au content. Interestingly, this method could be extended for other magnetic nanocomposites with two different kinds of noble metal nanocrystals integrated within one particle, such as Fe3O4@PDA/Au/PDA/Ag/PDA and Fe3O4@PDA/Au/PDA/Pd/PDA.
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SENSORS AND ACTUATORS B-CHEMICAL
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2015
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IF 4.097
Guihong Ding,Shi Xie,Yongmei Zhu,Ying Liu,Li Wang,Fugang Xu
An active surface-enhanced Raman scattering (SERS) substrate composed of graphene oxide (GO) wrapped gold nanoparticles (AuNPs) decorated-magnetic sphere Fe 3 O 4 (GO wrapped Fe 3 O 4 @Au hybrid) was prepared and used for aromatic dye detection. The hybrid was characterized by SEM, EDX, XRD, UV–visible spectroscopy and Raman spectroscopy. This hybrid showed high activity for SERS detection of aromatic dye due to the synergistic interaction among GO nanosheet, AuNPs and Fe 3 O 4 sphere. The dosages of AuNPs and GO were optimized to achieve a high sensitivity. The unique GO wrapped Fe 3 O 4 @Au hybrid has several advantages (such as high adsorption to target dye molecules, low noise response and high SERS enhancement ability) as SERS substrate over previously reported Fe 3 O 4 and AuNPs co-decorated GO sheet. Finally, the hybrid was successfully used for SERS detection of aromatic dye pollutant malachite green (MG) and nile blue A (NBA) even at concentration down to 1 nM and 0.1 nM, respectively. Potential of this substrate for multiplex detection of dye mixture (MG and NBA), and practical detection of MG in real sample were also evaluated. Our results suggested that the hybrid of GO wrapped Fe 3 O 4 @Au can be used as an efficient SERS platform for aromatic dye detection.
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NEW JOURNAL OF CHEMISTRY
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2014
·Vol. 38
·期 8
·3395-3400
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IF 3.159
Ai-Jun Wang,Jing-Jing Lv,Dan-Ling Zhou,Xuexiang Weng,Su-Fang Qin,Jiu-Ju Feng
In this report, ultrathin worm-like Au nanowires were constructed with the assistance of L-glutamic acid as a structure-directing agent and a weak stabilizing agent. The morphology of the Au products was found to be strongly dependent on the experimental parameters such as the amount of L-glutamic acid, as well as the reaction temperature. This synthesis was a seedless process, without using any template, surfactant, or toxic organic agent. Furthermore, the as-prepared Au nanowires were applied to facilely fabricate porous Au films with controllable thickness via simple gravity settling. The Au films showed high surface-enhanced Raman scattering (SERS) enhancement, using 4-mercaptobenzoic acid as a model probe. The Au films may be promising candidates for SERS sensing. This strategy provides an environmental friendly way for the preparation of various metal nanostructures with novel morphologies and useful applications.
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SENSORS AND ACTUATORS B-CHEMICAL
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2013
·
IF 3.535
Tao Qian,Chenfei Yu,Xi Zhou,Shishan Wu,Jian Shen
Au nanoparticles decorated polypyrrole/reduced graphene oxide hybrid sheets were facilely fabricated through a facile process. The prepared composite is dramatically obtained a crumpled and wrinkled surface, and uniform flower-like Au nanoparticles, which significantly improve the electrochemical properties in nano-molar level detection of dopamine. The novel sensor exhibits a remarkable sensitivity of 16.40 μA/μM with a linear range of 0.1–5000 nM and limit of detection as low as18.29 pM.
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Materials Research Express
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2014
·Vol. 1
·期 1
·015033
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IF 0
Yanyan Chen,Shenjie Li,Lijian Huang,Daocheng Pan
Au+ ions have been successfully incorporated into the lattice of ZnxCd1−xS quantum dots as luminescent centers via an aqueous method. The dopant emission can be tuned in the range of 445 to 570 nm, and the highest quantum yield can reach as high as 30%. Our results showed that Au+ ions can be used as an excellent luminescent dopant in doped quantum dots. Finally, these water-soluble quantum dots can be used directly in PL imaging of HepG2 cells without conjugating any biological targets, indicating a high potential application in bio-labeling.
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Journal of Physical Chemistry C
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2015
·
IF 4.772
Genlei Zhang,Zhaoyan Liu,Zhengli Xiao,Jiale Huang,Qingbiao Li,Yuxin Wang,Daohua Sun
Nanoparticles of Au–Pd with core–shell structure were synthesized through the coreduction of HAuCl4 and Na2PdCl4 in aqueous media by using cetyltrimethylammonium chloride as a reducing agent. The morphology and structure of the core–shell NPs were confirmed by transmission electron microscopy, X-ray diffraction, and UV–vis spectroscopy. We further demonstrate that the core–shell structure is formed as a synergistic result of low interfacial energy and small lattice mismatch between Au and Pd, different redox potentials of PdCl42–/Pd and AuCl4–/Au, and low reduction rates of HAuCl4 and Na2PdCl4. The catalyst of Au–Pd core–shell nanoparticles supported on Ni2P–graphite nanoplatelets (Au@Pd/Ni2P-GNPs) exhibits a noticeably higher activity than Pd and Pt catalysts in electrochemical ethanol oxidation. Moreover, we show that the activity and stability of Au–Pd core–shell for ethanol oxidation can be significantly enhanced using Ni2P nanoparticles as a cocatalyst. The prepared Au@Pd/Ni2P-GNPs catalyst exhibits a current density of 1.348 A mg–1metal, which is 2.1 times as high as that of Au@Pd/GNPs without Ni2P nanoparticles deposited.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2013
·
IF 2.39
Zhang-Ying Lv,Yao Fei,Wan-Yi Chen,Yan-Fei Tan,Chao-Qun Sun,Jian-Rong Chen,Ai-Jun Wang,Jiu-Ju Feng
In this report, a simple, facile, controllable, and green one-step electrochemical co-deposition method was developed for the preparation of hierarchical wheat-like Au–Pd heterostructures on a glassy carbon electrode (GCE) without any template or surfactant, only using l -glutamic acid as a growth directing agent. The control experiments associated with the applied potential, the molar ratio of HAuCl 4 to PdCl 2 , electrodeposition time, and concentration of l -glutamic acid were investigated in details. Meanwhile, the electrochemical experiments demonstrate the superior electrocatalytic activity of the Au–Pd heterostructures toward methanol oxidation, achieving a maximum catalytic current density of 45.8 mA cm −2 in the presence of 0.5 M methanol, much larger than those on pure Au (5.4 mA cm −2 ) or Pd (25.0 mA cm −2 ) under the same conditions.
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APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
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2015
·Vol. 120
·期 4
·1291-1297
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IF 1.704
Wang Xinyu,Ying Yulong,Hu Pan,Lei Jiahuan,Peng Xinsheng
CdS nanowires (NWs) are obtained by the sulfurization of Cd(OH) 2 nanowires at room temperature using H 2 S. The CdS NWs with diameter of 2–5 nm exhibit high photocatalytic performance due to the ultrafine size. To further improve the performance, Au nanoparticles (NPs) with different sizes, i.e., 5, 20, 40 and 100 nm, that decorated the CdS NWs are synthesized through a simple self-assembly and solid sulfuration process. The synthesized Au NPs–CdS NWs hybrids show higher photocatalytic efficiency than that of pure CdS NWs. Furthermore, 20 nm Au NPs–CdS NWs hybrids with an optimal Au loading of 3.2 wt% exhibit the highest photocatalytic efficiency. Both the enhanced separation of photoinduced hole–electron pairs and the absorption of visible light by incorporating Au NPs significantly improve the photocatalytic performance.
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MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
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2015
·
IF 1.955
Yonggan Hao,Xiankun Shao,Benxia Li,Luyang Hu,Tao Wang
The Au/TiO 2 hybrid nanofibers composed of mesoporous TiO 2 nanofibers and Au nanoparticles were synchronously fabricated by integrating a facile electrospinning technique and subsequent annealing in air. The Au loading content in the hybrid nanofibers was regulated by varying the dosage of chlorauric acid added in the precursor solution . The compositions, microstructures and optical response properties of the Au/TiO 2 hybrid nanofibers were characterized. The UV–vis spectra of the as-prepared hybrid fibers reveal two absorption bands belonging to the band gap absorption of TiO 2 and the surface plasmon resonance (SPR) of Au nanoparticles. For the catalytic reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride , the apparent reaction rate constant is raised but TOF value of the catalyst decreases, as the Au loading amount in the hybrid fibers increases. This is because the Au nanoparticles with smaller sizes have higher total surface areas at the same weight and therefore show higher catalytic activity . This method for producing Au/TiO 2 hybrid nanofibers is versatile and can be extended to the fabrication of other hybrid nanofibers composed of various noble metal nanoparticles and other mesoporous metal oxide nanofibers, designing of highly efficient catalysts for more important chemical reactions.
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