JOURNAL OF MATERIALS SCIENCE
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2015
·Vol. 50
·期 9
·3399-3408
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IF 2.371
Gao Yongju,Zhao Songfang,Zhang Guoping,Deng Libo,Li Jinhui,Sun Rong,Li Liyi,Wong Ching-Ping
Hierarchically porous organosilica microspheres have been facilely synthesized by improved self-assembly of flexible-bridged organosilica precursor without templates and harsh conditions. Subsequently, monodispersed silver nanoparticles (Ag NPs) are in situ grown on the porous microspheres via silver mirror reaction.
The as-prepared hybrid composites of Ag supported on porous microspheres are characterized by scanning electron microscopy, energy-dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, thermal gravimetric analysis and nitrogen adsorption and desorption, respectively. These results indicate that not only Ag NPs (20–40 nm) are grown on the organosilica uniformly but also the content of Ag NPs immobilized in the hybrid materials can be well controlled by simply tuning the amount of the Ag(NH 3 ) 2 OH. The resultant hybrid microspheres exhibit remarkable and durable performances for the reduction of 4-nitrophenol to 4-aminophenol by NaBH 4 in aqueous solution. Moreover, the catalytic kinetic mode can be tuned by adjusting the parameter in catalytic reaction, and it can be recycled for seven successive cycles with excellent conversion of 100 % within 8 min. Therefore, the present structure design and scalable route for the synthesis of hierarchical catalyst can provide a highly efficient solution for the reduction of nitro-aromatic compounds in the view of environmentally friendly strategy.
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Plasmonics
·
2015
·Vol. 11
·期 2
·565-572
·
IF 2.238
Zhu Jian,Wang Jing-Fei,Li Jian-Jun,Zhao Jun-Wu
By using the fluorescence spectroscopic techniques, the fluorescence quenching abilities of gold triangular nanoplates with silver coating have been studied. Because of the surface plasmon resonance (SPR)-induced nonradiative energy transformation, the fluorescence emission intensity of carcinoembryonic antigen (CEA) could be greatly quenched by the silver-coated-gold triangular nanoplates. By comparing with the bare gold triangular nanoplates, the nanoplates with silver coating exhibit greater fluorescence quenching ability and could be further improved by increasing the coating thickness. The fluorescence quenching effect also depends on the concentration of CEA. For bare gold triangular nanoplates, the quenching ability to CEA is decreased as the CEA concentration is increased. Whereas for silver-coated-gold triangular nanoplates, the quenching ability to CEA is increased as the CEA concentration is increased. By analyzing the intensity quenching of the fluorescence peak, CEA could be detected with an ultra-low detection limit of 5 pg/mL.
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BIOSENSORS & BIOELECTRONICS
·
2013
·
IF 5.437
Jingjing Zhu,Xincheng Song,Lang Gao,Zhenming Li,Zhan Liu,Shuang Ding,Shaobing Zou,Yu He
An effective dual-emission fluorescent Ag nanoclusters (NCs)-based probe have been constructed for rapid and selective detection of cysteine (Cys) with tunable sensitivity. Electrostatically induced reversible phase transfer method is employed to synthesize Ag nanoclusters with tunable emission intensity at 430 nm and 630 nm by controlling molar ratio between Ag and glutathione . The fluorescence of the Ag nanoclusters could be selectively quenched in the presence of Cys with a detection limit as low as 10 nM. Good linear correlations are obtained over the concentration range from 0.5 to 55 μM (quenched emission at 630 nm), 55 to 120 μM and 120 to 220 μM (enhanced emission at 555 nm) and 120 to 200 μM (quenched emission at 430 nm), respectively. The long-wavelength emission of the Ag nanoclusters can avoid the interference of the autofluorescence of the biosystems , which facilitated their applications in monitoring Cys in urine.
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INORGANIC CHEMISTRY
·
2013
·
IF 4.593
Yu-Peng Zhou,En-Bao Liu,Jin Wang,Hsiu-Yi Chao
Newly prepared gold(I) acetylide-based luminescent cation sensors 1c and 1d, which bear a novel three–armed flexible conformation, together with control molecule 2c, were synthesized in four steps. 1c and 1d exhibit the π → π* absorption of the acetylide ligands in fluid solutions and produce the 3(ππ*) emission of the acetylide ligands in the solid state and degassed THF solution. The 3(ππ*) emission of 1c in DMSO can be turned on upon addition of Ag+. The binding ratio between 1c and Ag+ as well as the binding constant log K were determined as 1:1 and 4.35 ± 0.12 respectively by UV–vis titration experiments. The formation of [1c·Ag]+ adduct, which leads to the appearance of new up-field peaks, was confirmed by 1H NMR spectroscopic titrations. The control 1H NMR titration experiments for the acetylide-free analogue 1a and single-armed analogue 2c indicate the acetylide groups and tripodal structures are responsible for the binding of Ag+. The control experiment for tripodal gold(I) acetylide analogue 1d suggests the change of PPh3 with P(2-Py)Ph2 induces similar binding affinity toward Ag+ but less selectivity toward Ag+. Free 1c also exhibits the anion binding affinity toward F–, but the Ag+ adduct [1c·Ag]+ shows less affinity toward F–.
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JOURNAL OF HAZARDOUS MATERIALS
·
2015
·
IF 4.529
Jiadong Xiao,Yongbing Xie,Qingzhen Han,Hongbin Cao,Yujiao Wang,Faheem Nawaz,Feng Duan
A comparative study was constructed to correlate the electronic property of the substituents with the degradation rates of phenolic compounds and their oxidation pathways under UV with Ag + /TiO 2 suspensions. It was verified that a weak electron withdrawing substituent benefited photocatalytic oxidation the most, while an adverse impact appeared when a substituent was present with stronger electron donating or withdrawing ability. The addition of p -benzoquinone dramatically blocked the degradation, confirming superoxide radicals ( O 2 − ) as the dominant photooxidant, rather than hydroxyl radicals, singlet oxygen or positive holes, which was also independent of the substituent. Hammett relationship was established based on pseudo-first-order reaction kinetics, and it revealed two disparate reaction patterns between O 2 − and phenolic compounds, which was further verified by the quantum chemical computation on the frontier molecular orbitals and Mulliken charge distributions of O 2 − and phenolic compounds. It was found that electron donating group (EDG) substituted phenols were more likely nucleophilically attacked by O 2 − , while O 2 − preferred to electrophilically assault electron withdrawing group (EWG) substituted phenols. Exceptionally, electrophilic and nucleophilic attack by O 2 − could simultaneously occur in p -chlorophenol degradation, consequently leading to its highest rate constant. Possible reactive positions on the phenolic compounds were also detailedly uncovered.
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EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
·
2015
·Vol. 2015
·期 28
·4731-4736
·
IF 2.942
Shuling Xu,Haibo Li,Lei Wang,Qiaoli Yue,Rui Li,Qingwang Xue,Yuanfu Zhang,Jifeng Liu
Graphical Carbon-encapsulated Cu–Ag dimetallic nanoparticles (C–CuAg NPs) were prepared using a facile one-pot route. The formation of C–CuAg NPs involved two steps: (1) the formation of the Cu–Ag alloy and (2) the in situ formation of the carbon layer at a low temperature (120 °C). The as-prepared C–CuAg NPs exhibited high catalytic activity and perfect reusability towards the reduction of 4-nitrophenol. A facile one-pot route has been developed for the synthesis of carbon-encapsulated Cu–Ag dimetallic nanoparticles (C–CuAg NPs). The synthesis was conducted using AgNO 3 and Cu(NO 3 ) 2 as metal precursors and ascorbic acid as the reduction agent and carbon source. The catalytic activities of the C–CuAg NPs for the reduction of 4-nitrophenol (4-NP) with NaBH 4 were tracked by UV/Vis spectroscopy, which demonstrates that the as-prepared C–CuAg NPs exhibit significantly enhanced catalytic activity compared with carbon-encapsulated Cu nanoparticles (C–CuNPs) and carbon-encapsulated Ag nanoparticles (C–Ag NPs). Notably, the catalysts are stable, and there is a high conversion efficiency for at least ten successive cycles. Considering the green facile preparation procedure and high catalytic activity, the prepared C–CuAg NPs hold great promise as highly efficient, cost-effective, and environmentally friendly catalysts for industrial applications.
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MATERIALS RESEARCH BULLETIN
·
2014
·
IF 1.968
Yunfang Chen,Jianzhang Fang,Shaoyou Lu,Yan Wu,Dazhi Chen,Liyan Huang,Weicheng Xu,Ximiao Zhu,Zhanqiang Fang
In this work, a new plasmonic photocatalyst Ag/AgI/BiOI-rectorite was prepared via a cation exchange process. The photocatalyst had been characterized by X-ray powder diffraction (XRD), Raman spectra, nitrogen sorption (BET), field-emission scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectroscopy (DRS). The photocatalytic activity, which was evaluated by degradation of rhodamine B (RhB) and bisphenol A (BPA) under visible light irradiation, was enhanced significantly by loading Ag/AgI/BiOI nanoparticles onto rectorite . The photogenerated holes and superoxide radical ( O 2 − ) were both formed as active species for the photocatalytic reactions under visible light irradiation. The existence of metallic Ag particles, which possess the surface plasmon resonance effect, acted as an indispensable role in the photocatalytic reaction.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2015
·
IF 4.097
Shaofei Zhang,Hui Yang,Ying Ma,Yu Fang
A bis-nitrobenzoxadiazole (NBD) derivative of calix[4]arene (L 1 ) and a control compound (L 2 ), mono-NBD derivative of the calixarene were designed and prepared via click chemistry. Fluorescence studies demonstrated that L 1 as created can function as a switch with the presence of Ag + in THF, of which the free state of L 1 emits at ∼527 nm, but the binding state at 576 nm. Based upon this discovery, L 1 was studied as a chemo-sensor of Ag + in a mixture solvent of THF and H 2 O with a detection limit (DL) of ∼6.2 × 10 −7 mol/L. Presence of other commonly found metal ions shows little effect upon the determination. Moreover, the L 1 in the Ag + -L 1 complex could be fully released with introduction of HCHO, a bases for the sensitive and selective detection of the toxic chemical. The DL of this test is 6.6 × 10 −7 mol/L. Interestingly, binding and releasing of the fluorescent ligand could be repeated for at least 5 times. Furthermore, both sensing could be performed in a visualized manner. It is believed that the fluorescent compound as created should have a potential to find real-life applications.
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RSC Advances
·
2014
·Vol. 4
·期 58
·30914-30922
·
IF 3.708
Mingxi Chen,Zhe Zhang,Lingzhi Li,Yu Liu,Wei Wang,Jianping Gao
Ultrafine Ag–Pd bimetallic nanoparticles homogeneously distributed on reduced graphene oxide (rGO) were prepared by redox reactions between Pd2+, Ag+ and GO. This method is simple, and the use of rGO as a support facilitated the separation and reuse of the Ag–Pd@rGO catalyst. The Ag–Pd@rGO bimetallic nanoparticles were characterized by ultraviolet-visible spectroscopy, Raman spectroscopy, thermogravimetric analysis, X-ray diffraction analysis, and X-ray photoelectron spectroscopy. The microstructure of the Ag–Pd@rGO was investigated with scanning electron microscopy and transmission electron microscopy. The Ag–Pd@rGO catalyst exhibited high catalytic activities in the Suzuki-Miyaura carbon coupling reaction and the Sonogashira carbon coupling (SCC) reaction. These reactions used mild, efficient, ligand-free and heterogeneous conditions. Interestingly, the presence or absence of oxygen in the SCC catalytic system resulted in two different products, in which oxygen can be used as “switch” to control different products.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2017
·
IF 3.133
Xing Yu,Junjie Li,Tielin Shi,Chaoliang Cheng,Guanglan Liao,Jinhu Fan,Tianxiang Li,Zirong Tang
In this article, uniform and anti-oxidative Cu-Ag core-shell nanoparticles with average particle diameter of 50 nm and Ag/Cu atomic ratio of 1/10 were synthesized by an environmental-friendly method. The morphology and core-shell structure of the obtained nanoparticles were observed through scanning electron microscope, transmission electron microscopy , energy-dispersive spectroscopy, and x-ray diffraction. Conductive inks were prepared by mixing the synthesized nanoparticles with the mixture of ethylene glycol and ethanol. The structure evolution and electrical resistivity of the Cu-Ag core-shell nanoparticle deposits were investigated upon heating up to 350 °C in comparison with pure Cu nanoparticles with similar sizes. A sintering mechanism was proposed to understand the sintering behavior of the Cu-Ag core-shell nanoparticles. It showed that dewetting of Ag shell through surface diffusion could effectively improve sintering performance at lower temperature besides its protection of Cu core from oxidation up to 156.3 °C.
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ELECTROCHIMICA ACTA
·
2016
·
IF 4.803
Yu Fan,Xingrong Tan,Xin Ou,Qiyi Lu,Shihong Chen,Shaping Wei
In this work, a novel “on-off” electrochemiluminescence (ECL) biosensor was successfully constructed for ultrasensitive detection of concanavalin A (ConA). The “signal-on” state with strong initial ECL signal was obtained by Ag-doped graphitic carbon nitride nanosheet (Ag-g-C 3 N 4 ), which was modified onto the glassy carbon electrode (GCE) for immobilizing phenoxy dextran (DexP) through π-π interaction. Then, the target ConA was anchored onto the DexP/Ag-g-C 3 N 4 modified film via the specific carbohydrate-ConA interaction. Successively, polyaniline-3,4,9,10-perylenetetracarboxylic acid-DexP conjugate (denoted as PANI-PTCA-DexP), as the ECL signal quenching probe, was incubated onto the electrode through the carbohydrate-ConA interaction to achieve the “signal-off” state. Here, PTCA was used as a matrix for the high loading of PANI and DexP, PANI served as the quencher towards Ag-g-C 3 N 4 system, and DexP as the recognition element for bounding ConA. With the formation of the sandwiched structure of DexP, ConA and PANI-PTCA-DexP, a desirable quenching ECL signal was measured with S 2 O 8 2− as the co-reactant of Ag-g-C 3 N 4 . The quenching effect of PANI towards Ag-g-C 3 N 4 is positively correlated with the concentration of ConA. With such an “on-off” system, the detection of ConA was achieved with a wide linear range from 0.001 ng/mL to 50 ng/mL as well as a low detection limit down to 0.0003 ng/mL.
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INORGANIC CHEMISTRY
·
2017
·
IF 4.857
Yu-Hang Fan,Hui-Yi Zeng,Xiao-Ming Jiang,Ming-Jian Zhang,Bin-Wen Liu,Guo-Cong Guo,Jin-Shun Huang
Quaternary metal thiophosphates containing second-order Jahn–Teller distorted d10 Ag+ and lone-pair cations, Ag3Bi(PS4)2 (1), Ag7Sn(PS4)3 (2), and Ag7Pb(PS4)3 (3), were obtained by solid-state synthesis. The structural frameworks of 2 and 3 feature an infinite 1-D interchiral double helix ∞1(Ag3P2S11), which is rare in inorganic compounds. Compound 3 undergoes a significant first-order structural phase transition from monoclinic to hexagonal at ∼204 °C. This can be ascribed to the significant mismatch in the expansion coefficients between Pb–S (Ag–S) and P–S bonds evaluated by bond valence theory. The three compounds are Ag+ ionic conductors, and Ag+ ion migration pathways are proposed by calculating maps of low bond valence mismatch. Moreover, the optical properties of the three compounds were studied, and electronic structure calculations were performed. The combination of second-order Jahn–Teller distorted d10 cation and lone-pair cation provides a new strategy to explore new metal thiophosphates with interesting structures and promising properties.
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