ULTRASONICS SONOCHEMISTRY
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2019
·
IF 7.279
F. Chen,C. Dong,C. Chen,W.D. Yin,W. Zhai,X.Y. Ma,B. Wei
Ultrasonic synthesis has shown great potential applications in preparing varieties of nanostructured materials. However, fabrication of nanomaterials with tunable structures and desirable properties is still challenging because of the instability and nonuniform distribution of cavitation effect in liquid phase. In this study, a novel aeration tuned ultrasonic synthesis approach is proposed for optimizing the cavitation effect in both time and space scales and fabricating SiO 2 @PNIPAm NPs. By alternation of ultrasonication and N 2 aeration, more and more gas bubbles are formed in the reaction liquid, and the collapse of those bubbles is further enhanced by the reactants of solid SiO 2 and intermediate functionalized SiO 2 NPs. As a result, SiO 2 @PNIPAm NPs with various grafting ratios are successfully synthesized simply by changing the number of ultrasonic synthesis cycle. The SiO 2 @PNIPAm NPs are subsequently used as stabilizer to form Pickering emulsions with different temperature response. This work provides a potential facile sonochemical synthesis method with high efficiency in obtaining inorganic/organic NPs of well determined structures.
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ELECTROCHIMICA ACTA
·
2019
·
IF 5.383
Jinhua Wu,Xiaoxi Zuo,Qiuyu Chen,Xiao Deng,Huiyin Liang,Tianming Zhu,Jiansheng Liu,Weijie Li,Junmin Nan
Poly(vinylidene fluoride-co-hexafluoro-propylene) doped with imidazole-modified silica nanoparticles (Z-SiO 2 ) is coated in a polyethylene substrate to form a functional composite polymer electrolyte (PVDF-HFP-(Z-SiO 2 )/PE-based CPEs) and used for high voltage LiNi 0.5 Co 0.2 Mn 0.3 O 2 cathode lithium-ion batteries (LIBs). The imidazole-based modified SiO 2 nanoparticles are first prepared via a distillation precipitation polymerization. The composite separators with 30 wt% Z-SiO 2 nanoparticles prepared via a dip-coating process exhibits a porous and uniformly dispersed morphology and enhanced performance, including excellent electrolyte uptake (310%), high ionic conductivity of 1.03 mS cm −1 , and oxidative decomposition voltage up to 4.75 V. More importantly, a stable cathode electrolyte interphase (CEI) layer can be formed, endowing the Li/PVDF-HFP-(Z-SiO 2 )/PE-based CPEs/LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523) cells superior cycling stability and rate capability (169 mAh g −1 , 81.9%) under when the charge cut-off voltage increased to 4.5 V, which is higher than that assembled with PE separator (160 mAh g −1 , 40.8%). These results demonstrate that the Z-SiO 2 nanoparticles not only act as the fillers of the CPEs but also are water/acid scavengers in favor of the formation of a stable CEI film, which promotes the cycling performance and rate capability of high voltage NCM523 cathode and reveals promising prospect for practical applications in LIBs at high voltage operation.
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CERAMICS INTERNATIONAL
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2019
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IF 3.45
Yang Chen,Chang Zhang,Ning Wang,Martin Jensen,Xianfeng Li,Xingxiang Zhang
Self-assembled ultralong Si 3 N 4 /SiO 2 nanowires (SiNNWs) with core-shell structure are prepared by air jet-spinning followed by high-temperature calcination employing low-cost fumed nano silica and industrial polyacrylonitrile as raw materials. Without using metal catalysts or reductive atmosphere, Si 3 N 4 /SiO 2 nanowires are generated through autocatalysis and self-assembly. The ultralong SiNNWs are uniform and continuous throughout the entire length with a 3–4 nm amorphous SiO 2 shell layer on surface of the Si 3 N 4 . The diameter of the SiNNWs is about 80–200 nm with the length being at centimeter level and the main component of the SiNNWs is the standard hexagonal cell of α-Si 3 N 4 . Moreover, the photoluminescence spectrum of SiNNWs exhibits an intense blue-green light emission at room temperature. The self-assembly mechanism of the SiNNWs is discussed.
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
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2019
·Vol. 30
·期 13
·12113-12121
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IF 2.195
Ruan Xuejun,Ren Xin,Zhou Wenting,Xu Xi,Wang Xin,Wang Manyu,Yan Ying,Yao Zheng,Shi Wen,Yu Wenqi
The effect of various proportions of SiO 2 and Cr 2 O 3 doping on the micro-characteristics and the electrical properties of the ZnO varistors were investigated. As the SiO 2 /Cr 2 O 3 ratio increased, the voltage gradient increased and then decreased, the nonlinear coefficient α increased, while the leakage current showed the opposite trend, meanwhile the residual voltage ratio was almost stable. When the SiO 2 /Cr 2 O 3 ratio was 1.7 mol% vs. 0.6 mol%, the ZnO varistors sintered at 1155 °C exhibited excellent comprehensive electrical properties with voltage gradient of 329.9 V/mm, nonlinear coefficient of 65.1, leakage current of 0 µA, residual voltage ratio of 1.663, and aging starting power of 0.72 W. The varistors were in good condition after being struck 18 times of 250 A square wave energy pulse impact, showing a great potential in the industrial application of power distribution systems.
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ACS Nano
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2019
·
IF 13.903
Wei Kou,Xiangcun Li,Yang Liu,Xiaopeng Zhang,Shaoran Yang,Xiaobin Jiang,Gaohong He,Yan Dai,Wenji Zheng,Guihua Yu
Here we report a highly scalable yet flexible triple-layer structured porous C/SiO2 membrane via a facile phase inversion method for advancing Li–sulfur battery technology. As a multifunctional current-collector-free cathode, the conductive dense layer of the C/SiO2 membrane offers hierarchical macropores as an ideal sulfur host to alleviate the volume expansion of sulfur species and facilitate ion/electrolyte transport for fast kinetics, as well as spongelike pores to enable high sulfur loading. The triple-layer structured membrane cathode enables the filling of most sulfur species in the macropores and additional loading of a thin sulfur slurry on the membrane surface, which facilitates ion/electrolyte transport with faster kinetics than the conventional S/C slurry-based cathode. Furthermore, density functional theory simulations and visual adsorption measurements confirm the critical role of the doped SiO2 nanoparticles (∼10 nm) in the asymmetric C membrane in suppressing the shuttle effect of polysulfides via chemisorption and electrocatalysis. The rationally designed C/SiO2 membrane cathodes demonstrate long-term cycling stability of 300 cycles at a high sulfur loading of 2.8 mg cm–2 with a sulfur content of ∼75%. This scalable yet flexible self-supporting cathode design presents a useful strategy for realizing practical applications of high-performance Li–S batteries.
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CARBON
·
2020
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IF 8.821
Yue Liu,Fengrui Zhang,Wenxia Zhu,Dong Su,Zhiyuan Sang,Xiao Yan,Sheng Li,Ji Liang,Shi Xue Dou
Removing contaminants from wastewater is critical to secure the global water supply. Membrane technologies for water purification are exceptionally attractive due to their high efficiency and low energy consumption. The traditional porous polymer films , however, are easy to be fouled by the organic pollutants, causing pore blockage and deteriorated separation performance. We herein report the rational design of a porous SiO 2 /GO hybrid membrane by coupling graphene oxide (GO) nanosheets with SiO 2 nanoparticles and using ethylenediamine to crosslink them, for efficient oil/water separation and dye removal. The SiO 2 nanoparticles provide an excellent hydrophilicity and underwater superoleophobicity interface, resulting in efficient and antifouling oil/water separation with an outstanding rejection rate over 99.4% for different types of oil; and the hierarchical scaffold, formed from the hydrophilic GO nanosheets embedded with SiO 2 nanoparticles, greatly facilitates the rapid permeation of water with a high flux rate of up to 2387 L m −2 h −1 for pure water and 470 L m −2 h −1 for oil/water separation. Moreover, the abundant functional groups on the GO surface also render this membrane with a high removal capability for dye blocking, enabling it to remove soluble pollutants in molecular dimensions as well. This design strategy not only provides an outstanding membrane for water purification but also sheds light on the design of multi-purpose functional membranes for a variety of energy and environment-related applications.
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INORGANIC CHEMISTRY
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2019
·
IF 4.85
Dandan Wu,Runping Jia,Ming Wen,Shuai Zhong,Qingsheng Wu,Yongqing Fu,Shuhong Yu
A nanostructural catalyst with long-term durability under harsh conditions is very important for an outstanding catalytic performance. Herein, a new ultrastable PtCo/Co3O4–SiO2 nanocatalyst was explored to improve the catalytic performance of carbon monoxide (CO) oxidation by virtue of the surface active lattice oxygen derived from strong metal–support interactions. Such a structure can overcome the issues of Co3O4–SiO2 inactivation by water vapor and the Pt inferior activity at low temperature. Further, Co3O4–SiO2 nanosheets endow superior structure stability under high temperatures of up to 800 °C, which gives long-term catalytic cyclability of PtCo/Co3O4–SiO2 nanocomposites for CO oxidation. Moreover, the large specific surface areas (294 m2 g–1) of the nanosheet structure can expose abundant surface active lattice oxygen, which significantly enhanced the catalytic activity of CO oxidation at 50 °C over 30 days without apparent aggregation of PtCo nanoparticles after 20 cycles from 50 to 400 °C. It can be expected to be a promising candidate as an ultrastable efficient catalyst.
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LANGMUIR
·
2019
·
IF 3.683
Yichen Li,Xiaohui Wang,Mingan Hu,Lan Zhou,Liqin Chai,Qinguo Fan,Jianzhong Shao
Patterned structural color photonic crystals (PCs) based on periodic photonic nanostructures have attracted great interest in developing high-performance sensors and other smart optical materials as well as tunable structurally colored fashion textiles. However, previously reported patterned PCs with both high color saturation and tough mechanical strength were difficult to achieve, which restricts their practical applications. Herein, arbitrarily patterned silica/polyurethane acrylate (SiO2/PUA) inverse opal photonic crystals (IOPCs) with high color saturation and tough mechanical strength were innovatively designed and fabricated by writing with photopolymerizable PUA “ink” on a self-assembled hollow SiO2 PC template. The high color saturation of the prepared SiO2/PUA IOPCs originated from the high refractive index contrast between the encapsulated air-filled core and the SiO2/PUA composite skeleton. The cross-linked flexible PUA matrix tightly warped the self-assembled hollow SiO2 nanospheres together, endowing the obtained SiO2/PUA IOPCs a structural color pattern with tough mechanical strength. The structural colors of SiO2/PUA IOPCs could be finely tuned by regulating their basic parameters, and a redshift in the resultant structural color was observed due to an increase in the lattice constant when increasing the core size and/or shell thickness of the hollow SiO2 nanospheres.
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CONSTRUCTION AND BUILDING MATERIALS
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2019
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IF 4.046
Yamei Cai,Dongxing Xuan,Chi Sun Poon
Swelling caused by alkali-silica reaction (ASR) in concrete is a deleterious behavior due to reactions between alkaline pore solution and amorphous or metastable forms of silica in aggregates. Generally, mitigation by using pozzolanic materials is commonly adopted. This study compared the effectiveness of a highly-reactive nano-SiO 2 (NS) and a slowly-reactive waste glass powder (WGP) on mitigating ASR of cement mortars prepared with crushed glass cullet as aggregates. The experimental results showed that incorporating 2% NS or 10% WGP or a hybrid of the two in the mortar can decrease the ASR expansion. Using WGP resulted in larger reduction in the ASR expansion than using NS. Meanwhile, there was an improvement of strength from 7 d to 28 d for the mortar prepared with WGP. The composition of reaction products containing the ASR gel formed in a simulated ASR condition and the macro-/micro-structure of the tested mortars were further analyzed. It was found that the reaction products formed with high ratios of Na/Si and Ca/Si were favorable in mitigating the ASR expansion. For the specimen prepared with WGP, the increase in the ratio of Ca/Si would increase the stiffness of the ASR gel, and a higher Na/Si ratio would help reduce the osmotic pressure. The findings from this study would be useful for the selection of pozzolans to mitigate the ASR effect when using crushed glass cullet as aggregates in cement mortars.
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RSC Advances
·
2018
·Vol. 8
·期 35
·19486-19493
·
IF 2.936
Gang-Tian Zhu,Fei Liu,Sheng He,Xiao-Mei He,Shu-Kui Zhu,Yu-Qi Feng
Magnetic aqueous ammonia (MAA) was prepared as a magnetic extractant for dispersive microextraction of petroleum acids (PAs). The amount of extractant in MAA was custom-made by a simple approach. In the MAA composed of an aqueous ammonia coating and Fe3O4@SiO2 core, the coating is a base extractant that can selectively extract acids, while the magnetic core serves as a support to achieve dispersion as well as rapid magnetic retrieval of the extractant during the extraction processes. This is the first use of reusable, stable and modifiable Fe3O4@SiO2 as a support instead of bare Fe3O4 in a magnetic particle assisted dispersive liquid–liquid microextraction technique. The parameters that affect extraction efficiency were investigated. The sampling step as well as the desorption step can be completed in 2 min. The linear ranges are 5–5000 ng g−1, while the limits of quantification range from 2.5 to 6.2 ng g−1. The recoveries in spiked crude oil samples are in the range of 79.1% to 112.1% with relative standard deviations less than 11.3% (intra-day) and 13.4% (inter-day). Finally, the proposed method was applied to the analysis of PAs in diluted crude oils with different maturities. In comparison to the existing methods for extraction of PAs, the proposed method provides superior performances including high throughput (12-well plate), high degree of sample clean-up, and low consumption of separation material, solvent and time.
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Green Processing and Synthesis
·
2019
·Vol. 8
·期 1
·667-676
·
IF 1.128
Dan Chen,Binglin Li,Bin Li,Xiaoli Zhang,Longhui Wei,Wenwen Zheng
Catalytic efficiency in synthesis of vitamin E succinate was dramatically increased via the preparation of robust catalyst and the improvement of reaction system. 4-dimethylaminopyridine (DMAP) was covalently immobilized on nano-SiO 2 to avoid the catalyst contamination of the product and permit the easy recycling of DMAP. Then, a hexane-acetone mixed solvent system was firstly introduced to replace the traditional single-solvent system, which was employed to improve the activity of immobilized DMAP derivative and the substrate solubility of the reaction system. The highest vitamin E succinate yield of 94% was achieved. In addition, the recyclability and stability of the immobilized DMAP derivative was excellent, the yield of vitamin E succinate had no obvious loss and remained 90% after recycling 20 times. The excellent results make this technology be a promising candidate for the industrial production of vitamin E succinate.
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CHEMICAL PHYSICS LETTERS
·
2018
·
IF 1.686
Qingqian Fan,Yueping Guan,Zhi Zhang,Guoli Xu,Yu Yang,Chen Guo
A new method was developed for preparing monodisperse Fe 3 O 4 @SiO 2 magnetic core-shell nanoparticles via three steps. The obtained nanoparticles exhibit high saturation magnetization, good surface topography and dispersion as characterized by FTIR, SEM and VSM. The experimental results of hydrochloric acid treatment show that the obtained nanoparticles have excellent acid resistance and stable and compact silicon coating. The magnetic core-shell nanoparticles were further tested for purification of plasmid DNA from E. coli DH5a cells. The result of purification leaded to better adsorption, elution and purity results in comparison with isolated commercial extraction kit.
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危险品化学品经营许可证（带存储）