KOREAN JOURNAL OF CHEMICAL ENGINEERING
·
2019
·Vol. 36
·期 12
·2125-2132
·
IF 2.476
Qu Shuguo,Zhang Chenchen,Li Minhui,Zhang Yan,Chen Lunbo,Yang Yushuai,Kang Bo,Wang Yiwei,Duan Jihai,Wang Weiwen
Making inexpensive proton exchange membrane with high proton conductivity for the proton exchange membrane fuel cell (PEMFC) is still a challenging problem. Graphene oxide (GO) nanoparticles grafted with (3-amino-propyl) triethoxy silane (APTES) were prepared and then incorporated into sulfonated poly(ether ether ketone) (SPEEK) matrix by solution casting to make the composite proton exchange membrane. The obtained nanoparticles and composite membranes were characterized by XRD, FT-IR, Raman, TGA, SEM, and UTM. GO treated with the silane coupling agent improved the dispersion stability and compatibility of GO in SPEEK, which decreased the agglomeration of GO nanoparticles in the SPEEK membrane. The prepared nanocomposite membranes exhibited better water retention properties and proton conductivity. The proton conductivity of the SPEEK membrane with 2 wt% amine functionalized GO (AGO) reached 11.32 mS/cm at 120 °C, which was 2.45-times higher than that of the pristine SPEEK membrane. The reason was that AGO nanoparticles disperse uniformly in the SPEEK membranes, which provides new channels for proton transfer. The potential application of this composite membrane in the PEMFC was indicated.
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Scientific Reports
·
2019
·Vol. 9
·期 1
·1-7
·
IF 4.011
Zhang Xin,Zhang Haiyan,Yan Sheng,Zeng Zugang,Huang Anshou,Liu Anping,Yuan Yuan,Huang Yingzhou
Sensitive in situ detection of organic molecules is highly demanded in environmental monitoring. In this work, the surface enhanced Raman spectroscopy (SERS) is adopted in microfluidics to detect the organic molecules with high accuracy and high sensitivity. Here the SERS substrate in microchannel consists of Ag nanoparticles synthesized by chemical reduction. The data indicates the fabrication conditions have great influence on the sizes and distributions of Ag nanoparticles, which play an important role on the SERS enhancement. This result is further confirmed by the simulation of electromagnetic field distributions based on finite difference time domain (FDTD) method. Furthermore, the SERS spectra of organic molecule (methylene blue) obtained in this plasmonic microfluidic system exhibit good reproducibility with high sensitivity. By a combination of SERS and microfluidics, our work not only explores the research field of plasmonics but also has broad application prospects in environmental monitoring.
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Horticulture Environment and Biotechnology
·
2019
·Vol. 61
·期 1
·197-206
·
IF 1.531
Mao Deshou,Liu Hong,Li Zhengfeng,Niu Yunwei,Xiao Zuobing,Zhang Fengmei,Zhu Jiancai
We obtained volatile aroma compounds from the juices extracted from three different Red Delicious apple ( Malus domestica ) varieties, which included esters, alcohols, and aldehydes. Among these compounds, ethyl 2-methylbutanoate, methyl 2-methylbutanoate, ethyl butanoate, ethyl hexanoate, hexanal, and butyl 2-methylbutanoate showed high odour active values in the juices. Four compounds (ethyl 2-methylbutanoate, ethyl octanoate, ethyl butanoate, and ethyl hexanoate) were selected to investigate possible interactions occurring in the apple juices. The results demonstrated that the additions of these four aroma volatile compounds could decrease the threshold and intensity of the sensory notes of the solutions compared to those without the addition of these compounds. Lastly, ethyl 2-methylbutanoate was added to the solutions to investigate interactions with σ–τ function. Here, σ represents the ratio of the aroma intensity of the mixed solution to the sum of aroma intensities of all compounds in the solution before blending. The τ represents the aroma of the mixture ratio between the mixture and the sum of aroma compounds before mixing. The results clearly indicated that additive or synergistic effects occurred among these volatiles at sub-threshold concentrations.
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MICROCHIMICA ACTA
·
2019
·Vol. 186
·期 12
·1-7
·
IF 5.479
Li Shuhuai,Ma Xionghui,Pang Chaohai,Tian Hai,Xu Zhi,Yang Yan,Lv Daizhu,Ge Huilin
A fluorometric assay is described for the determination of Cd(II) in environmental and agricultural samples. It is making use of a molecularly imprinted polymer (MIP) and aptamer as dual recognition units, while carbon quantum dots (co-doped with sulphur and nitrogen) and gold nanoparticles (SN-CQD/Au) act as the fluorophores. The aptamer-modified MIP was placed on an SN-CQD/Au-modified indium tin oxide glass electrode. Cd(II) was detected with high selectivity by the recognition sites of the aptamer in the MIP. Fluorescence, with excitation/emission peaks at 370/430 nm, is quenched by Cd(II). Response is linear in the 20 pM to 12 nM concentration range. The detection limit is 1.2 pM. The sensor is selective for Cd(II), and recoveries from spiked waters, soils and vegetables real-world samples range between 82.1 and 113.9%.
A fluorescence sensor composed of a molecularly imprinted polymer and an aptamer as a dual identification system for Cd 2+ coupled with and carbon quantum dots (co-doped with sulphur and nitrogen) and gold nanoparticles (SN-CQDs/Au) as fluorescent element that can detect Cd 2+ with high selectivity by a dual-recognition mechanism.
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JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE
·
2019
·Vol. 28
·期 12
·7213-7226
·
IF 1.476
Yang Ming,Jia Zhengfeng,Pang Xianjuan,Shao Xin,Zhen Jinming,Zhang Ran,Ni Junjie,Jiang Jinlong,Yu Bo
In this paper, polydopamine/silver (PDA/Ag) nanoparticles were easily synthesized. Then, the PDA/Ag nanoparticles were sprayed on copper substrate and heat-treated under argon to get carbonized PDA/Ag (CPDA/Ag) composite films. Transmission electron microscopy, field-emission scanning electron microscopy, x-ray diffraction, Raman spectroscopy and x-ray photoelectron spectroscopy were employed to investigate the conversion of PDA and AgNO 3 into CPDA and Ag,
respectively. Results showed that the PDA/Ag composite films heat-treated at 500 °C had much better friction reduction and anti-wear properties than other samples. The tribofilms containing C, N, O, Ag and Cu played an important role on reducing friction and increasing wear resistance.
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JOM
·
2019
·Vol. 72
·期 1
·247-252
·
IF 2.305
Yan Hengwei,Liu Zhanwei,Ma Wenhui,Huang Liqiang,Wang Chengzhi,Liu Yingxin
The development of low-temperature aluminum electrolysis makes it possible to reduce energy consumption and greenhouse gas emissions. The KF-NaF-AlF 3 -based electrolyte is a promising low-temperature electrolyte for aluminum reduction. The liquidus temperatures of KF-NaF-AlF 3 electrolytes with a total cryolite ratio (CR t ) fixed at 1.3–2.0, and with different concentrations of NaF (with a step change of 5 mol.%), were investigated by the cooling curve method. The results showed that the liquidus temperature of KF-NaF-AlF 3 mixtures increases with the increase of the CR t , which has a bigger influence on the liquidus temperature than the traditional NaF-AlF 3 electrolyte currently used in aluminum smelters. When the content of NaF is 10–20 mol.%, the curves of the liquidus temperature vs. NaF content reach a peak. When the NaF content ranges from 30 to 40 mol.%, the liquidus temperature is relatively low (695–900°C). The precipitated order of the compounds in molten KF-NaF-AlF 3 electrolytes with a CR t of 1.3 is as follows: K 2 NaAlF 6 (or K 3 AlF 6 ) → Na 3 Al 5 F 14 → K 2 NaAl 3 F 12 → KAlF 4 .
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MICROCHIMICA ACTA
·
2019
·Vol. 186
·期 12
·1-8
·
IF 5.479
Zhong Yao,Yu Xinyue,Fu Wanying,Chen Yanwei,Shan Guiye,Liu Yichun
Gold-silver core-shell nanoparticles (Au@Ag NPs) were prepared by two successive reductions in a seed-growth method. The Au@Ag NPs are used as both a colorimetric and Raman spectroscopic probe for ultrasensitive determination of H 2 O 2 and glucose. It is found that H 2 O 2 (as produced from glucose by the action of glucose oxidase) can directly oxidize and gradually corrode the silver shell of the Au@Ag NPs. This results in a drop in the surface plasmon resonance absorbance at 400 nm, and the color of the solution changes from brownish yellow to purple. Without adding any additional chromogenic agents, the color change can be visually observed and detected photometrically. Silver NPs also are an excellent surface-enhanced Raman scattering (SERS) substrate. Due to corrosion of the silver shell, the SERS intensity (measured at 1083 cm −1 ) gradually decreases with increasing glucose concentration. The detection limits are 300 nM of glucose for the colorimetric assays, and 20 nM for the SERS assay.
Schematic representation of the method for glucose determination. H 2 O 2 can oxidize and gradually corrode the silver shell of the gold-silver core-shell nanoparticles. This results in a distinct color change of the solution from brownish yellow to purple, and a drop in SERS intensity. The effect is applied in colorimetric and Raman spectroscopic assays for glucose.
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JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2019
·Vol. 140
·期 5
·2111-2122
·
IF 2.471
Cheng Jian,Yan Jingchun,Wang Lei,Zhang Rongxian,Liu Zuliang,Wang Rui,Li Zhenming
Abstract A new family of metal-free and energetic graphene oxide (GO)-based burning rate catalysts (FGO 1–6 ) with excellent catalytic and desensitization performances for ammonium perchlorate (AP) were synthesized by nucleophilic substitution reaction of energetic functional groups with acylated GO. The chemical structures, thermal stabilities, catalytic properties and desensitization performances of the functionalized GO were determined. It was shown that the functional groups on the nanosheets of GO imparted its energetic performance and thermal stability, and the catalytic properties and desensitization performances were also enhanced. The reduced mass loss rate along with enhanced residues formation indicated significant improvement in thermal stabilities for FGO 1–6 compared with GO. Besides, not only did FGO 1–6 lower the decomposition temperature, but also enhanced the overall heat for the thermal decomposition of AP. The FGO 1–6 decreased the exothermic peak of the high-temperature decomposition process of AP by 88.1, 93.4, 98.3, 85.8, 90.7 and 79.8 °C, corresponding to the decomposition heat of AP increased significantly from 655 to 2707, 2915, 3529, 3002, 3642 and 2718 J g −1 , which exhibited better catalytic activity than that of GO. In addition, the mechanical sensitivities of AP/GO and AP/FGO 1–6 mixtures decreased obviously in comparison with pure AP were also obtained. Graphic abstract A new family of metal-free and energetic GO-based burning rate catalysts with excellent catalytic properties and desensitization performances for ammonium perchlorate were developed.
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Applied Nanoscience
·
2020
·Vol. 10
·期 6
·1845-1851
·
IF 2.88
Wang Tianxiong,Jiang Tiancai,Meng Xianquan
We found that the morphology of nanowires could be regulated by adding polyvinylpyrrolidone (PVP, K30) in hydrothermal synthesis of antimony sulfide (Sb 2 S 3 ) nanowires. The nanowires with length more than 20 μm were obtained by adding the proper amount of PVP. Three kinds of fully nanostructured photodetector using Sb 2 S 3 nanowires as active regions were fabricated and the first detector used silver nanowires as the electrodes at both ends, the second used silver nanowires as one electrode and MXenes as the another electrode, and the third used MXenes as both electrodes. The light response speed of the photodetector with both MXenes electrodes was improved greatly. The photodetector which used MXenes and silver nanowires as electrodes at two ends, respectively, showed the phenomenon of being self-driven. The mechanism of asymmetric hole migration was put forward to explain the effect of being self-driven.
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FIBERS AND POLYMERS
·
2019
·Vol. 20
·期 10
·2017-2024
·
IF 1.439
Ding Yadan,Xu Dan,Shao Hong,Cong Tie,Hong Xia,Zhao Huiying
SiO 2 /polystyrene porous micro/nanofibers with superhydrophobic and superoleophilic properties were prepared by facile electrospinning method. The spindle-beads-on-string structured fibers were found to be more hydrophobic than those without the beads. The doping of nano-SiO 2 endowed the fibers with porous structure, and thus further increased the water contact angle from 139° to 153°. Simultaneously, the oil contact angle of 0° was obtained. The superhydrophobic-superoleophilic micro/nanofibers could selectively absorb oil from water within eight seconds. The oil sorption process followed pseudo-first order kinetic model. The absorption mechanism was proved to be physical encapsulation by Fourier transform infrared technique. The maximum sorption capacity for highly viscous silicone oil was up to 122.7 g/g. It is higher than many recently reported values. The porous micro/nanofibers exhibit significant value in oil-water separation.
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JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
·
2019
·Vol. 94
·期 1
·186-194
·
IF 1.986
Wang Qiuhua,Wang Huiying,Wu Yaling,Cheng Lingping,Zhu Lunan,Zhu Junchen,Li Zhidong,Ke Yanxiong
Sub 2-μm monodisperse mesoporous silica spheres (MMSS) were synthesized using a mixed template system in a MeOH/H 2 O solution. 1-Dodecylamine (DDA) and polymeric type Jeffamine surfactants, including D2000, D4000, and T5000, were employed as templates. These mixed template syntheses realized to gain MMSS materials with good spherical shape and uniform particle size. When the MeOH/H 2 O (v/v) ratio was controlled between 2.5:1 and 3.0:1, mesoporous silica spheres of 2.10–2.35 μm with excellent dispersibility can be obtained. Depending on the surfactant chain length of Jeffamine, hydrothermal aging pH (4–9), time (12–24 h), and temperature (80–140 °C), MMSS with large-pore sizes (up to 14.3 nm), surface areas (153–791 m 2 /g), and pore volumes (0.47–1.28 cm 3 /g) can be synthesized.
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MICROCHIMICA ACTA
·
2019
·Vol. 187
·期 1
·1-8
·
IF 5.479
Xi Ying,Du Yingxiang,Sun Xiaodong,Zhao Shiyuan,Feng Zijie,Chen Cheng,Ding Wen
A monolithic capillary column was prepared by single-step copolymerization of the ionic liquid 1-vinyl-3-octylimidazolium bromide (VOI) and styrene. The VOI and styrene monomers were introduced to provide multiple interaction sites and increase hydrophobicity and aromaticity of the monolithic column, respectively. The effect of porogen ratio, monomer ratio and reaction temperature on permeability was investigated. The resulting column was characterized by scanning electron microscopy, and the results suggest that the column possesses high porosity and good homogeneity. A relatively strong anodic electroosmotic flow was generated over a wide range of pH values (pH 2.0–10.0), and this facilitates the rapid separation of analytes within 12 min. Alkylbenzenes, polycyclic aromatic hydrocarbons (PAHs), proteins and amino acids were used to evaluate the performance of the monolithic column under capillary electrochromatography mode by UV detection. Mixed-mode retention mechanisms including hydrophobic interaction, π-stacking, ion-exclusion interaction were observed. The monolithic column exhibits high column efficiency (8.72 × 10 4 plates∙m −1 ) and satisfying separation capability (the resolution of four alkylbenzenes: 2.54, 2.86 and 4.62, four PAHs: 2.79, 4.83 and 4.77, three proteins: 4.35 and 2.86, two amino acids: 3.34).
Schematic representation of capillary electrochromatography (CEC) systems with ionic liquid and styrene based organic polymer monolithic column for separation of alkylbenzenes, polycyclic aromatic hydrocarbons, proteins and amino acids.
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