MATERIALS CHEMISTRY AND PHYSICS
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2015
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IF 2.259
Yang Li,Taotao Wu,Mujie Yang
Nanocomposites of quaternized and crosslinked poly(4-vinylpyridine) (QC-P4VP) and silver nanoparticles were prepared by a two-step procedure, and characterized by Fourier-transform infrared spectroscopy, Ultraviolet–visible spectroscopy and scanning electron microscopy. Bilayer-structured humidity sensors based on the nanocomposites were fabricated, and the effects of the concentration of silver salt precursor and poly(4-vinylpyridine), the method for the reduction of silver salt, the deposition order of the sensitive layers and environmental temperature on the humidity sensing characteristics of the composite sensor have been examined at room temperature. The composite sensor exhibited low impedance under dry atmosphere due to the introduction of Ag nanoparticles, and could detect very low relative humidity (RH) (down to 1% RH) with good sensitivity (impedance change of 2000% from 1% to 30% RH). In addition, the composite sensor demonstrated very wide measuring range (1–98% RH), and revealed faster response and smaller hysteresis than the sensor based on QC-P4VP alone. The complex impedance spectra of the composite sensor in the environments with different RH levels were investigated to explore its humidity sensing mechanism.
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RSC Advances
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2015
·Vol. 5
·期 15
·11349-11357
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IF 3.84
Yong Yang,Guozhong Wang,Gang Gu,Qian Li,Shenghong Kang,Yunxia Zhang,Dickon H. L. Ng,Huijun Zhao
A facile and economical one-pot microwave-assisted approach for the synthesis of Ag decorated yolk@shell structured TiO2 microspheres (Ag-TS) is reported. The rapid and uniform microwave heating could reduce the reaction time to 30 min, an order of magnitude shorter than that of conventional methods. The characterization data confirmed that the resultant mesoporous structured Ag-TS were highly uniform in size with an average diameter of ∼0.5 μm, which was constructed by small anatase TiO2 nanoparticles, along with Ag nanoparticles ranging from 10 to 50 nm homogeneously dispersed on the microspheres. Nitrogen adsorption–desorption measurement revealed that all the Ag-TS samples had high specific surface areas (>100 m2 g−1) and abundant mesoporous structures. The growth model of Ag-TS was proposed based on a series of contrast experiments, the unique selective heating of reaction solvent (deionized water and ethanol) by the microwave method was found to be critical. At the initial stage, amorphous solid microspheres were formed by heating of ethanol molecules through absorbing microwave energy due to the better microwave absorbing performance. Then water molecules were heated by the microwave irradiation, the crystallization of anatase TiO2 on the surface of the solid microspheres started, followed by the Ti species diffusing spontaneously towards the outer surface of the solid microspheres and leading to the formation of the outer shell due to the Ostwald ripening process. Finally, water continuously diffused through the outer shell and guided the subsequent crystallization of anatase TiO2, resulting in the formation of the core. Besides, the application of Ag-TS for the removal of water contaminants including toxic heavy metal hexavalent chromium (Cr(VI)) ions and organic dye methylene blue (MB) were also evaluated.
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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
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2013
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IF 2.672
Xiaoquan Lu,Li Wang,Dong Liu,Jie Du,Haifeng Wang
An interesting phenomenon that significant cathodic electrochemiluminescence of tris(2,2′-bipyridine)ruthenium(II) with assistance of metal nanoparticles (Ag, Cu) on Pt electrode was observed for the first time in acid buffer solution. This is different from that only anodic electrochemiluminescence occurs when bare Pt electrode is used. Both anodic and cathodic ECL peaks were found at 0.4 V with positive potential scan and 0 V with negative initial potential scan, respectively, in the presence of Ag. A possible mechanism was proposed that Ag might act as a co-reactant to ignite cathodic ECL of Ru ( bpy ) 3 2 + system in low pH condition, which was similar to the result we observed previously in the case of Au. Considering high market price of Au, relatively cheaper metal Ag is more promising for potential application in ECL.
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JOURNAL OF APPLIED POLYMER SCIENCE
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2015
·Vol. 132
·期 37
·
IF 1.768
Shan Li,Jianxin Xiong,Jingsong Shen,Yong Qin,Juan Li,Fuqiang Chu,Yong Kong,Linhong Deng
A novel electrochemical sensor based on Ag nanoparticles (AgNPs) decorated polyaniline/graphene composites (PANI/G) is developed, which can be used for sensitive determination of H 2 O 2 . For the construction of the H 2 O 2 sensor, polyaniline (PANI) is first electrodeposited on the surface of graphene (G) to form PANI/G, and then horseradish peroxidase (HRP) loaded on AgNPs (HRP/AgNPs) is immobilized on to the PANI/G. H 2 O 2 can be catalyzed by HRP to generate current response which can be significantly enhanced by AgNPs, and thus the PANI/G based sensor can be utilized for the detection of H 2 O 2 . Under the optimized conditions, the proposed H 2 O 2 sensor exhibits wide linear response to H 2 O 2 concentration ranging from 0.25 to 2.25 m M with a detection limit of 0.03 m M (signal-to-noise ratio of 3), and it also shows high selectivity and reproducibility. The method is simple and cost-effective, and can be a promising candidate as the sensitive sensing platform for H 2 O 2 . © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132 , 42409.
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MATERIALS AND MANUFACTURING PROCESSES
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2014
·
IF 1.486
Quan Zhang,Fei Li,Xinyuan Chang,Deliang He
Photocatalytic activities of three composites, namely nickel foam/Ag-TiO2, nickel foam/Ag-ZnO, and nickel foam/Ag-WO3, were evaluated for toluene degradation in a home-made cuboid photoreactor. Scanning electron microscopy and energy dispersive spectrometry were employed to characterize these photocatalysts. The photodegradation effects of the three photocatalysts peaked under 60% relative humidity, with nickel foam/Ag-TiO2 exhibiting the highest rate of photocatalytic toluene degradation. Controlling humidity could enhance the photocatalytic toluene degradation activities of the three composites, which are significantly affected by a wider band gap. In this study, a dynamic model was proposed and analyzed according to the time-dependent photodegradation of toluene.
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PHYSICAL CHEMISTRY CHEMICAL PHYSICS
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2014
·Vol. 16
·期 28
·14706-14712
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IF 4.198
Xuan He,Hui Wang,Zhongbo Li,Dong Chen,Qi Zhang
An efficient and green approach was used to fabricate novel and low-cost surface-enhanced Raman scattering (SERS) spectroscopy sensors based on 4-aminothiophenol (4-ATP) functionalized ZnO–Ag hybrid nanoflowers for the detection of explosives. Such SERS sensors exhibited high sensitivity to rhodamine 6G (R6G) at a low concentration of 10−12 M and an enhancement factor of over 4.12 × 106 was achieved. Moreover, the Raman-inactive trinitrotoluene (TNT) initiated the high Raman scattering of non-resonated 4-ATP through the formation of a π-donor–π-acceptor interaction between the π-acceptor, TNT, and the π-donor, the 4-ATP–Ag–ZnO complex, on the flower-like hybrids. Because this π-donor–π-acceptor interaction could effectively induce the “hot spots” for SERS, TNT concentrations as low as 5 × 10−9 M could be detected. Furthermore, other derivatives of TNT were also explored, and this sensor exhibited better selectivity for TNT than other similarly structured explosives. The low-cost hybrid SERS substrates presented good sensitivity and reproducibility for the analytes employed, demonstrating promising application in forensic science and homeland security.
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PubMed
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APPLIED SURFACE SCIENCE
·
2017
·
IF 3.387
Xia Yang,Yi He,Xueling Wang,Ruo Yuan
Mercuric ion (Hg 2+ ) is one toxic metal ion existed in aquatic ecosystems which would seriously damage human central nervous system and other organs. So developing an approach to sensitively detect Hg 2+ in our living environment is urgent and important. In this work, a novel surface enhancement Raman spectrum(SERS) sensor is fabricated for high selective and ultrasensitive detection of Hg 2+ in aqueous solution, based on a stable thymine-Hg 2+ -thymine (T-Hg 2+ -T) structure and the π - π interaction between single-stranded DNA (ssDNA) and single walled carbon nanotubes (SWCNTs). Herein, SWCNTs act as Raman labels to produce characteristic Raman peaks which can be a beacon to quantitative detect Hg 2+ . In the presence of Hg 2+ , the ssDNA can capture Hg 2+ forming T-Hg 2+ -T structure, which makes SWCNTs leave the hot spots of the SERS-based biosensor. With this design, the Raman intensity of SWCNTs decreased with the increasing concentration of Hg 2+ . At the same time, CoFe 2 O 4 @Ag as active SERS substrates can effectively enhance sensitivity and uniformity of the biosensor through aggregation by magnet. Under optimal conditions, this proposed biosensor can detect Hg 2+ at a range from 1 pM to 100 nM with a detection limit of 0.84 pM. With the advantages of good sensitivity, selectivity, simplicity and rapidity, the biosensor is potentially suitable for monitoring of Hg 2+ in environmental applications.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2017
·
IF 9.446
Qixing Zhou,Shuanglong Ma,Sihui Zhan
Ordered mesoporous Ag/CeO 2 nanocomposites were prepared by combining nanocasting with photo-assisted reduction. The heterogeneous photoreactivity of the prepared samples was tested for inactivating Escherichia coli ( E. coli ). These mesoporous Ag/CeO 2 nanocomposites exhibited superior photocatalytic disinfection efficiency than mesoporous CeO 2 and bulk CeO 2 , respectively. Doping Ag species could extend the absorption range to visible light area and enhance the concentration of Ce 3+ ions and oxygen vacancies, which had significant influence on the surface properties of CeO 2 . Moreover, it is the first time to verify that created midgap states through doping Ag can significantly lower the threshold of incident photon energy and broaden the adsorption spectrum demonstrated by experimental studies and density functional theory (DFT) calculations. The enhanced disinfection mechanism was attributed to the fact that the novel mesoporous structure can promote the mass transfer process and the interfacial interaction between Ag species and CeO 2 and lead to reduced recombination of free charges, rapid separation and transportation of photogenerated electrons-holes. This work provides a new method to develop novel mesoporous plasmonic photocatlysts for disinfection using solar radiation.
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RSC Advances
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2016
·Vol. 6
·期 17
·14105-14111
·
IF 3.289
Hua-Zhou Zhao,Yi Xu,Chun-Yan Wang,Rong Wang,Song-Tao Xiang,Li Chen
A “sandwich” microfluidic surface enhanced Raman scattering (SERS) chip with Ag film@nanoAu prepared in a microchannel was proposed and fabricated in situ. The integrated composite Ag film@nanoAu was prepared in situ by way of chemical plating and self-assembly. Firstly, the preparation conditions were optimized. On the basis of that, the influence of the laser focus position along the vertical direction and the materials of the cover plates on the SERS effect were investigated and optimized in detail. The optimized SERS effect was observed when the laser was focused on the interface of the sample and the SERS substrate. The SERS intensity of Rhodamine 6G (R6G) decreased 2.5 times and 2.1 times when PDMS or glass was used as the cover plate separately. Compared to single gold and silver SERS substrates, the composite of Ag film@nanoAu integrated in the microfluidic channel resulted in the peak intensity increasing 3–5 times during the SERS detection of R6G at 1507 cm−1. The enhancing effect could be attributed to the change in the local electromagnetic field which was caused by the synergistic sensitizing effect between the Au nanoparticles and the underlying silver mirror film. It was illustrated that the detection limit for R6G was 10−8 M and the enhancement factor (EF) was 3.8 × 105 with a relative standard deviation (RSD) of approximately 10% in the as-prepared microfluidic SERS chip.
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CHEMISTRY-A EUROPEAN JOURNAL
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2017
·Vol. 23
·期 62
·15721-15728
·
IF 5.317
Yuanyuan Hu,Dong Xie,Yang Wu,Nangui Lin,Aixin Song,Jingcheng Hao
Graphical Stacking gels : Factors affecting the self-assembly of supramolecular hydrogels composed of combining 5′-adenosine monophosphate and Ag + are discussed (see figure). The gelation capability was enhanced by increasing the concentration of Ag + or decreasing the pH. The gels are very sensitive to light and have potential applications as photosensitive materials. Supramolecular hydrogels obtained by combining 5′-adenosine monophosphate (AMP) with Ag + were fabricated in this work. Their gelation capability was enhanced by increasing the concentration of Ag + or decreasing the pH. The gels are very sensitive to light, which endows them with potential applications as visible-light photosensitive materials. Coordination between the nucleobase of AMP and Ag + , as well as π–π stacking of nucleobases, are considered to be the main driving forces for self-assembly. The hydrogels successfully achieved the encapsulation and enrichment of biomolecules. Hydrogen bonding between the amino group of guest molecules and silver nanoparticles along the nanofibers drives the enrichment and is considered to be a crucial interaction.
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SENSORS AND ACTUATORS B-CHEMICAL
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2017
·
IF 5.401
Yao Yao,Mingli Yin,Junqing Yan,Dong Yang,Shengzhong (Frank) Liu
Ag-WO 3 core-shell nanospheres (CSNSs) are fabricated for gas sensor applications. It is found that the sensor based on Ag-WO 3 CSNSs dramatically improve the sensor performance towards alcohol vapor, with significantly lower optimum working temperature (260 °C) and superior detection limit (0.20 ppm) comparing to pure WO 3 hollow nanospheres (HNSs). The Ag-WO 3 sensor displays an ultrahigh sensitivity under visible light illumination. When illuminated under a 150 W xenon arc light source, the response is increased from 62 to 160, the optimum working temperature is reduced from 260 to 190 °C, and the detection limit is improved from 0.20 to 0.032 ppm. This work may offer an attractive strategy to improve sensitivity of light-enhanced plasmonic metal-oxide based gas sensors.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2017
·
IF 3.133
Junjie Li,Xing Yu,Tielin Shi,Chaoliang Cheng,Jinhu Fan,Siyi Cheng,Tianxiang Li,Guanglan Liao,Zirong Tang
In this paper, we proposed a depressing bonding temperature method for Cu Cu bonding with nanoparticle paste. The paste was prepared by composting dominant Cu nanoparticles with Ag nanoparticles of lower sintering temperature , where the average nanoparticle size of Cu and Ag was 61.02 and 69.25 nm, respectively. The reliable bonding was successfully achieved at the temperature of 250 °C, the pressure of 1.12 MPa and the protection of Ar-H 2 gas mixture comparing with pure Cu nanoparticles paste. An optimal resistivity of sintered Cu-Ag composite nanoparticle paste can achieve 1.99 × 10 −7 Ω m with the 2:1 molar ratio of Cu to Ag, and the largest shear strength of the bonded Cu-Cu joint can reach 25.41 MPa. The underlying sintering mechanism of the composited nanoparticles was discussed. It suggests the compositing with Ag nanoparticles is a practical strategy towards lowering the bonding temperature for Cu-based interconnect. The experimental process can be easily implemented, the bonding temperature and the performance can satisfy the packaging requirements of current 3D-IC. The developed Cu-Ag composite nanoparticle paste is also promising for packaging of other thermal and force sensitive chips.
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