JOURNAL OF POROUS MATERIALS
·
2019
·Vol. 27
·期 1
·295-301
·
IF 1.947
Zhang Jiayue,Kong Yong,Jiang Xing,Zhong Ya,Chen Ying,Shen Xiaodong
Hydrophobic silica aerogel (HSA) was synthesized by a facile sol–gel method and ambient pressure drying with methyltrimethoxysilane as precursor. The effect of precursor concentration on the sol–gel behavior, structure, and thermal conductivity of HSA was investigated. HSA with apparent density of 0.088 g/cm 3 showed a thermal conductivity of 0.018 W/(m·K), a specific surface area of 502 m 2 /g and a pore volume of 1.66 cm 3 /g. The hydrophobic groups in HSA had a good thermal stability up to 450 °C. Polypropylene felt was used to synthesize hydrophobic silica aerogel composite (HSAC). The effect of sol loading on the structure and thermal conductivity of HSAC was investigated. HSAC with equivalent sol loading exhibited a low shrinkage of 2.5% and a low thermal conductivity of 0.020 W/(m·K). Finally, the preparation method of the HSA is facile and environmentally friendly, and the resulting composite is a promising candidate for thermal insulation under humid environments.
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2019
·Vol. 31
·期 1
·226-238
·
IF 2.195
Shen Yongqian,Wei Yupeng,Li Jian,Zhang Yuchen,Li Bin,Lu Xuefeng,Ji Binghan,Yan Pengze,Du Xueyan
Electromagnetic (EM) wave absorbing materials with superhydrophobic property and enhanced microwave absorbing ability are very important for the application of stealth technologies, especially in humid conditions. In the present work, the electrospinning technique was employed to fabricate NiAc/PVA nanofibers (NFs) from nickel acetate tetrahydrate (NiAc) and poly(vinyl alcohol) (PVA) solution as precursors, while the PVA component was further pyrolyzed and carbonized to obtain Ni/NiO/C NFs. Microwave absorption performance and EM parameters of the prepared NFs were then investigated from 2.0 to 18.0 GHz. Comparative studies between different samples elucidated not only the possible causes for lose mechanisms, but also impedance matching. According to the experimental results, when NiAc/PVA NFs contained 8% NiAc, the calcinated Ni/NiO/C NFs could achieve an optimum reflection loss of − 33.9 dB at 10.4 GHz under a thickness of 2.5 mm and exhibit an effective frequency bandwidth of 5.7 GHz. Furthermore, the membrane of Ni/NiO/C NFs with the best absorption property exhibited robust hydrophobicity and the contact angle was 144.9°, It shows that the obtained Ni/NiO/C NFs have a broad application prospect in waterproof stealth materials.
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MICROCHIMICA ACTA
·
2019
·Vol. 187
·期 1
·1-9
·
IF 5.479
Zhang Wanqing,Fan Shumin,Li Xinli,Liu Shanqin,Duan Dawei,Leng Leipeng,Cui Chengxing,Zhang Yuping,Qu Lingbo
A glassy carbon electrode (GCE) was modified with a composite prepared from phytic acid, polypyrrole and a ZIF type metal-organic framework (PA/PPy)/ZIF-8@ZIF-67). The nanocomposite was prepared by in-situ chemical polymerization in the presence of ferric chloride and subsequently functionalized with PA to form PA/PPy/ZIF-8@ZIF-67. The materials were characterized by XRD, FT-IR, BET, XPS, SEM and TEM. The modified GCE was applied to individual and simultaneous detection of Pb(II) and Cu(II), with peak voltages of −0.6 and − 0.1 V, respectively (vs. SCE). The amount of PPy, the ZIF-8@ZIF-67 concentration, polymerization potential, polymerization time and pH value were optimized. Under optimized conditions, the calibration plots have two linear ranges. These are from 0.02 to 200 μM and from 200 to 600 μM for Pb(II), and from 0.2 to 200 μM and 200 to 600 μM for Cu(II). The detection limits are 2.9 nM and 14.8 nM, respectively. Simultaneous detection of Pb(II) and Cu(II) is also demonstrated. The good performance of the electrode is attributed to the large surface area of ZIF-8@ZIF-67, the good electrical conductivity of PPy, and the metal complexation power of PA. The modified GCE was successfully applied to the determination of Pb(II) and Cu(II) in real samples and gave satisfactory recoveries.
Schematic presentation of the construction process of PA/PPy/ZIF-8@ZIF-67/GCE sensor, and the mechanism of Pb(II) and Cu(II) at the prepared sensor.
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Food Analytical Methods
·
2019
·Vol. 13
·期 2
·403-411
·
IF 2.413
Liu Weihua,Wang Jing,Yu Wenlong,Wang Xianghong
Flumequine (FLU) is widely used as an antibiotic in the treatment and control of animal diseases, which may result in the presence of residues harmful to humans in food products of animal origin. A novel and fast biomimetic enzyme-linked immunosorbent assay (BELISA) was developed for the determination of FLU based on a molecularly imprinted polymer (MIP) as a selective affinity agent. With an optimized molar ratio of FLU to methacrylic acid (MAA) of 1:2 determined by molecular dynamic simulations, the MIP was directly synthesized on the surface of a 96-well plate (as solid support) with FLU as the template molecule, MAA as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, and azodiisobutyronitrile (AIBN) as the initiator. Under the optimized conditions, the BELISA method was established with a sensitivity (IC 50 ) of 0.141 μg/mL and a detection limit (IC 15 ) of 1.09 × 10 −3 μg/mL. The developed method was applied to determine FLU concentrations in spiked beef and shrimp samples, with satisfactory recovery values ranging from 80.7 to 92.2% with relative standard deviations ( n = 3) between 3.3% and 7.0%. This method can be used for the rapid determination of FLU in animal foods and has promising applications in food safety monitoring.
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JOURNAL OF MATERIALS SCIENCE
·
2019
·Vol. 55
·期 8
·3167-3180
·
IF 3.442
Ren Lipei,Yu Yan,Yang Yuan,Zhang Qian,Xiao Xingfang,Liu Ruina,Xu Weilin
Zeolitic imidazolate framework-8 (ZIF-8) is regarded as an excellent adsorbent material for removing diverse toxic or hazardous gases. However, its milli- to nanoscale size typically restricts its applications. In this study, we demonstrate the ZIF-8 nanocrystals assembled on TiO 2 -coated activated carbon fiber felts via atomic layer deposition (ZIF-8@ALD-ACF felts), which can be used as a highly efficient adsorbent for HCHO removal. Using the TiO 2 -coated ACF felts as substrates via ALD can provide large number of growth sites for ZIF-8 nanocrystals, which results in fast and highly efficient removal of HCHO. Furthermore, ZIF-8@ALD-ACF felts achieve a highly efficient removal of HCHO under ultraviolet (UV) light. HCHO can be completely removed at high concentration within 110 min. Moreover, under UV light, it can be completely removed at low concentration within 6 min. The micropores in ACF and nanocages in ZIF-8 are suitable for small molecular HCHO uptaking and provide sufficient contact time for photocatalysis by TiO 2 . The ALD technology provides a useful methodology for the practical application of MOF-based materials.
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IONICS
·
2019
·Vol. 26
·期 3
·1347-1356
·
IF 2.289
Qu Yuning,Wen Shuya,Chen Jianhong,Shen Honghui,Yu Wenjie,Wei Dan,Yu Jianguo,Kwon Young-Uk,Zhao Yongnan
In this work, we synthesized a Pd nanonetwork (PdNN) catalyst by employing Nafion as structure-directing agent. The nanonetwork-like structure is interconnected by Pd particles. Moreover, the morphologies and the sizes of PdNN samples can be tunable by adjusting concentrations of Pd precursor. The as-prepared PdNN catalysts have superior hydrogen evolution reaction (HER) performance to that of commercial Pd/C. Among them, PdNN-4.5 catalysts exhibit the most excellent hydrogen evolution performance, which contains an overpotential of 59 mV at 10 mA cm -2 and a Tafel slope of only 54 mV dec -1 . Besides, a super stability is also displayed for PdNN-4.5 catalysts. The significant improvement in the HER performance of the PdNN-4.5 catalyst may be attributed to the nanonetwork-like structure, the sizes, and the interaction between the Pd catalysts and Nafion. Thus, this work can provide a simple method for synthesizing the highly efficient Pd-based catalyst for HER.
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MICROCHIMICA ACTA
·
2019
·Vol. 187
·期 1
·1-10
·
IF 5.479
Li Yue,Wang Yan,Wang Mingchao,Zhang Jinyue,Wang Qingwei,Li Hongji
In a new method for the determination of trace levels of chlorophenols in river waters, detection via surface-enhanced Raman scattering (SERS) is combined with recognition by a molecularly imprinted polymer (MIP). Nanoparticles of type Cu 2 O@Ag were synthesized by attaching silver particles to the surface of Cu 2 O nanoparticles. The Cu 2 O@Ag were then coated with a layer of a MIP that was obtained by atom transfer radical polymerization using from methacrylic acid as monomers and 2,6-dichlorophenol as the template. The morphology of Cu 2 O is found to be flower-like. The Cu 2 O@Ag-MIPs displays a strong SERS effect. Following removal of the template by rinsing with the mixture solution of methanol/acetic acid (9/1, v /v), the material was used to selectively bind 2,6-dichlorophenol, 2,4-dichlorophenol and 2,4-dichlorophenol. The SERS peak intensity at 1580 cm −1 increases linearly with the concentration of the various chlorophenols in the range from 10 nM to 1 mM, and the detection limit is 5.8 nM. The imprinting factor is 4.62. The method was applied to the analysis of (spiked) river water, with recoveries ranging from 91.8 to 115.4% and relative standard deviations of <4.5%.
Graphical abstract
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JOURNAL OF ELECTRONIC MATERIALS
·
2020
·Vol. 49
·期 3
·2100-2109
·
IF 1.774
Yazdan Ali,Wang Jizhe,Nan Ce-Wen,Li Liangliang
The role of thermal interface materials (TIMs) has become substantial due to their critical applications in electronic devices for effective heat dissipation. Dimethyl silicone oil-based thermal pastes are widely used as TIMs because they can provide an intimate bonding between the heat sink and the electronic chip; however, the thermal conductivities of typical silicone oil-based thermal pastes are low. In this study, we prepared thermally conductive emulsion-based thermal pastes with two kinds of boron nitride (BN) fillers and investigated their rheological behavior and thermal conductivities. The emulsion was composed of dimethyl silicone oil, n-butanol, and sorbitan monooleate (Span 80) as an emulsifier. The fillers were boron nitride fibers (BNFs) and boron nitride nanosheets (BNNSs). The viscosity, storage modulus, and loss modulus of the emulsion-based pastes were smaller than those of the corresponding silicone oil-based ones. The thermal conductivities of the emulsion based pastes were larger than those of the silicone oil-based ones because of their lower viscosity and higher baseline thermal conductivity. The pastes with BNNSs had larger thermal conductivities in comparison with the corresponding ones with BNFs. To further enhance the thermal conductivity, BNNSs were coated with two silane coupling agents, 3-aminopropyl-triethoxy silane (KH550) and 3-(Trimethoxysilyl)propyl methacrylate (KH570), and then introduced into the emulsion. The maximum thermal conductivity was 1.04 W m −1 K −1 for the emulsion-based paste with KH550-coated BNNSs at a filler loading of 39 vol.%, which was a ∼ 7-fold increase in comparison with that of neat silicone oil (0.13 W m −1 K −1 ).
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CHEMICAL PAPERS
·
2019
·Vol. 74
·期 4
·1189-1197
·
IF 1.246
Feng Yinxia,Su Biquan,Xian Liang,Ma Yongjun,Sheng Li,Cao Ningjing
This paper presents the visible light-assisted synthesis of surfactant-free Pt nanoparticles (Pt-NPs) supported on multi-walled carbon nanotubes (MWCNTs) at ambient condition. Transmission electron microscopy (TEM) images indicate that Pt-NPs with high density and relative small in size (about 2 nm) were monodispersed on the surface of MWCNTs. The characterizations of Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffractometer (XRD) and ultraviolet–visible spectroscopy (UV–Vis) prove that visible light irradiation significantly affect the species distribution of [PtCl 4 ] 2− precursor in the hydrolysis and then promote hydrolysate Pt oxides loading on MWCNTs. The loading process decides the morphology of Pt-NPs rather than the following precursor reduction, which does not change the morphology but only the valance state of platinum. The catalytic activity of Pt/MWCNTs was tested in subsequent methanol electrochemical reactions and 4-nitrophenol (4-NP) reduction.
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COLLOID AND POLYMER SCIENCE
·
2019
·Vol. 297
·期 10
·1255-1264
·
IF 1.906
Peng Jing,Tang Dongyan,Lv Haitao,Wang Ning,Yang Xu,Sun Zhaojie,Yu Zaiqian
Here, cloud temperature and aggregation behaviors of poly( N -vinyl caprolactam)-based polymer were investigated with the addition of hydrophilic units. Copolymers composed of N -vinyl caprolactam and polyethyleneglycol methylacrylate (POEGMA) were firstly synthesized through a reversible addition fragmentation chain transfer technology with benzylsulfanylthiocarbonylsulfanyl propionic acid (BPA) as chain transfer agent and 4,4′-azobis(4-cyanovaleric acid) as initiator. The cloud points measurements indicated that comparing with pure poly( N -vinyl caprolactam), little amount of POEGMA would dramatically decrease copolymers’ cloud temperature while further addition of POEGMA would inversely increase the cloud temperature. The contribution of POEGMA within polymeric chains was modulated by adding POEGMA after 30 min of initiating polymerization. Both the DLS and TEM measurements showed that micelles instead of random structures were formed through a self-assembling process above the cloud temperature. These results emphasized the importance of the contribution of hydrophilic units in predicting the thermal phase transition behavior of poly( N -vinyl caprolactam)-based materials. Graphical abstract
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RESEARCH ON CHEMICAL INTERMEDIATES
·
2019
·Vol. 46
·期 1
·149-164
·
IF 2.064
Sun Jialin,Dai Jingtao,Liu Rui,Yang Xiaowei,Chen Jian
To improve the visible-light catalytic performance of TiO 2 for practical application, Ag/AgBr modified TiO 2 was fabricated in ionic liquid–water medium via a facile hydrothermal reduction method. Imidacloprid (IMI) was employed as the target pollutant to evaluate the critical impacts on the catalytic activity of as-prepared Ag/AgBr/TiO 2 , where the factors relating to the catalyst (composition, dosage, recycle and reuse) and solution chemistry (pH and concentration, simulated wastewater samples and floodwater of rice paddy field) were studied. The results suggested that benefitting from visible-light sensitive Ag/AgBr and high specific surface area TiO 2 , Ag/AgBr/TiO 2 exhibits superior visible-light photocatalytic activity and stability to Ag/AgBr and TiO 2 . The quenching tests with various scavengers indicate that · O 2 − and h + , and · O 2 − and · OH may be the key roles in IMI photo-degradation on Ag/AgBr and on Ag/AgBr/TiO 2 , respectively. Thus, the photocatalytic performance of Ag/AgBr/TiO 2 differs from that of Ag/AgBr. Furthermore, the contribution of such active species is clarified for quantitative mechanisms study. The photo-degradation conducted in the simulated wastewater and the floodwater of rice paddy field proves favorable anti-interference capacity of Ag/AgBr/TiO 2 . The tests conducted on real wastewater sample verified that Ag/AgBr/TiO 2 can mineralize IMI promptly and almost completely.
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Scientific Reports
·
2019
·Vol. 9
·期 1
·1-9
·
IF 4.011
Yang Yushan,He Haishan,Li Yougui,Qiu Jian
Robust, buoyant, superhydrophobic PVB/SiO 2 coatings were successfully formed on wood surface through a one-step solvothermal method and a nanoimprint lithography method. The as-prepared PVB/SiO 2 /wood specimens were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), thermogravimetric/differential thermogravimetric (TG–DTG) analyses. The superhydrophobic property and abrasion resistance of rose-petal-like wood were measured and assessed by water contact angle (WCA) and sand abrasion tests. The results show that PVB/SiO 2 /wood not only exhibited a robust superhydrophobic performance with a WCA of 160° but also had excellent durability and thermostability during the sand abrasion tests and against corrosive liquids. Additionally, the as-prepared PVB/SiO 2 /wood specimens show high buoyancy.
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