Reaction Kinetics Mechanisms and Catalysis
·
2018
·Vol. 125
·期 1
·199-211
·
IF 1.515
Hao Fang,Yang Yongzhe,Xiong Wei,Liu Pingle,You Kuiyi,Luo He’an
Mesoporous SiO 2 –Al 2 O 3 supported Cr 2 O 3 catalysts were prepared by the sol–gel and impregnation methods. These catalysts were characterized and applied in cyclohexane nitrosation reaction. The effects of the preparation conditions and the catalyst deactivation were studied. The results show that 20% Cr 2 O 3 /SiO 2 –Al 2 O 3 catalyst calcined at 400 °C exhibits not only the larger surface area, smaller particle size, but also the larger amount of Cr 2+ and Brønsted acid sites. These catalysts show good catalytic performances in the cyclohexane nitrosation to ε-caprolactam and could be recycled for several times in this reaction system for the first time. The catalyst of Cr 2 O 3 /SiO 2 –Al 2 O 3 calcined at 400 °C gives 10.8% conversion with 79.9% selectivity to ε-caprolactam.
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Journal of Applied Spectroscopy
·
2018
·Vol. 85
·期 1
·160-165
·
IF 0.611
Neng Jing,Wang Xujun,Jia Kan,Sun Peilong
Fe 3 O 4 nanoparticles were first modified with tetraethoxylsilane to form Fe 3 O 4 /SiO 2 nanoparticles, followed by the addition of 3-aminopropyltriethoxysilane and 3-thiolpropyltriethoxysilane to introduce –NH 2 and –SH groups to the surface of Fe 3 O 4 /SiO 2 nanoparticles. Gold nanoparticles were further assembled on the surface of Fe 3 O 4 /SiO 2 via the electrostatic adsorption of –NH 2 and the Au–S bond to produce stable core–shell Fe 3 O 4 /SiO 2 /Au gold/magnetic nanoparticles. These Fe 3 O 4 /SiO 2 /Au gold/magnetic nanoparticles were characterized by a variety of techniques such as transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX), and afterwards conjugated with tetrodotoxin antibodies (Ab) and used as a Raman active substrate (Fe 3 O 4 /SiO 2 /Au–Ab) with Rhodamine B (RhB)-labeled tetrodotoxin antibody as a Raman reporter (Ab–RhB). Upon mixing these reagents with tetrodotoxin (TTX), a sandwich complex [Fe 3 O 4 /SiO 2 /Au–Ab···TTX···Ab–RhB] was generated due to the specific antibody–antigen interactions. The immunocomplex was subsequently separated by an externally applied magnetic source and concentrated into a pellet point, where the laser interrogation of the pellet produced a strong signal characteristic of RhB. The logarithmic intensity of the signal was found to be proportional to the concentration of TTX with a limit of detection of 0.01 μg/mL and a detection linearity range of ~ 0.01–0.5 μg/mL. The established method eliminates the complicated procedures of traditional centrifuging, column separation, and incubation and achieves a rapid detection of tetrodotoxin with improved detection sensitivity.
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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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ULTRASONICS SONOCHEMISTRY
·
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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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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Solar RRL
·
2017
·Vol. 1
·期 12
·1700151
·
IF 0
Xiaoman Zhang,Jialei Liu,Dongxing Kou,Wenhui Zhou,Zhengji Zhou,Qingwen Tian,Yuena Meng,Sixin Wu,Aocheng Cao,Canbin Ouyang
Metallic nanoparticles (NPs) exhibit a surface plasmon resonance (SPR) and can be incorporated into perovskite solar cells (PSCs) to improve cell performance. However, the incorporation of Au NPs in bulk films of PSCs requires large concentration to keep interval distance and would cause worse device performance. In this work, a universal strategy for significant increasing power conversion efficiency (PCE) of PSCs through incorporating high aspect ratio Au nanorods (NRs)@SiO 2 into perovskite/spiro-OMeTAD interface is demonstrated. The key feature of this approach is that we can take advantage of the SPR at a lower concentration and the Au NRs have larger light scattering section than AuNPs. It is found that the SPR and scattering effect of Au NRs lead to a broad enhancement of photon absorption. Furthermore, a superior enhanced charge separation process in the Au NRs incorporated device is also observed. Benefitting from this cooperative plasmonic effect of Au NRs in optical and electrical aspects, both short-circuit current density and open-circuit voltage are improved, resulting in the new device delivering a PCE up to 17.39% from 14.39%. This result further supports that Au NRs can play a more effective SPR effect at perovskite/spiro-OMeTAD interface, rather than incorporating them into bulk films.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2017
·
IF 5.401
Wenmin Yin,Long Wu,Fan Ding,Qin Li,Pan Wang,Jinjie Li,Zhicheng Lu,Heyou Han
To circumvent the limitations of natural antibodies, receptor, or enzyme, molecular imprinting technique has received intensive attention in analytical methods Herein, based on surface enhanced Raman scattering (SERS) molecularly imprinted polymer (SERS-MIP), a SERS-MIP sensor has been developed for the sensitive and selective detection of bisphenol A (BPA). To construct the BPA sensor, raspberry-type SiO 2 @Ag nanoparticles (SiO 2 @Ag NPs) were prepared to act as supporting substrate, and BPA was adopted as template molecule, tetraethyl orthosilicate (TEOS) as functional monomer and 3-aminopropyltriethoxysilane (APTES) as cross-linker. Due to the strong plasma resonance character of Ag NPs, the SERS-MIP sensor showed good sensitivity in the detection of BPA. The core-shell and satellite-like structure of the SiO 2 @Ag composites could provide a large surface area for BPA recognition by molecular binding domains. In addition, the sensor could prevent interferences such as 4,4′-(Hexafluoroisopropylidene) diphenol (BPAF) and 4,4′-Dihydroxybiphenyl (DOD). Moreover, the real water samples were tested to verify the reliability and feasibility of the method. Under the optimal conditions, the proposed method behaved good analytical performance to BPA with a wide linear range from 1.75 × 10 −11 to 1.75 × 10 −6 M and a detection limit of 1.46 × 10 −11 M.
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NANOTECHNOLOGY
·
2017
·Vol. 28
·期 41
·415301
·
IF 3.44
Sanyuan Hu,Heping Li,Zhen Su,Youwei Yan
This paper describes a near-field electrospinning technique combined with heat treatment process used to directly align parallel metal oxide and metal nitride fibers on silicon dioxide substrate. The effects of near-field electrospinning parameters (including collector-to-needle distance, applied voltage and the moving speed of the collector) on the morphology of the resulted fibers have been studied. Metallic salt-contained precursor fibers are individually aligned via near-field electrospinning of metallic salts and polymeric solution mixtures. After applying calcination process to these well aligned precursor fibers, patterning by metal oxide and metal nitride fibers such as ZnO, Ga2O3, TiO2, GaN and TiN is successfully obtained. The optical microscope images and the scanning electron microscopy show the presence of fiber patterns, whose crystalline structure is characterized by x-ray diffraction and Raman spectroscopy measurement. The results demonstrate the potential of this approach for assembling ceramic fibers into parallel arrays with controllable orientation and position.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2022
·
IF 6.371
Xiaoguang Sun,Chengcheng Ma,Fubin Ma,Tong Wang,Chao Feng,Wei Wang
The self-healing performance of anticorrosive coatings is critical to restoring their protective function in the event of failure to ensure durability in harsh corrosive conditions. In this work, a novel self-healing anticorrosive coating was fabricated by two-dimensional transition metal carbides and carbonitrides (MXenes) and mesoporous silica nanoparticles (MSNs) loading tannic acid (TA) as corrosion inhibitors that can effectively protect low-carbon steel from corrosion damage. The TA as corrosion inhibitors were loaded into the mesoporous silica nanoparticles, and the loading capacity reached about 71.71%. The synthesized epoxy/TA@MXene-SiO 2 coating was characterized in detail using different tools. The epoxy/TA@MXene-SiO 2 coating had excellent anticorrosive performance and an impedance modulus of 2.826 × 10 6 Ω cm 2 at 0.01 Hz. The impedance modulus reached the maximum peak value of 8.585 × 10 6 Ω cm 2 after 132 h of continuous immersion. In addition, the TA made a coating with an electrochemical self-healing efficiency of 114.27 kΩ cm 2 h −1 . This work provides insight into the novel design of anticorrosive coatings with excellent anticorrosive performance and high self-healing efficiency.
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JOURNAL OF LUMINESCENCE
·
2023
·
IF 3.6
Rongliang Deng,Xiaotong Fan,Guolong Chen,Changzhi Yu,Xiao Yang,Yue Lin,Hao-Chung Kuo,Tingzhu Wu,Zhong Chen
Rigid protection layers for the lead-halide perovskite effectively enhance its stability. In this work, for the most vulnerable CsPbI 3 perovskite nanocrystals (PNCs), we introduced zero-dimensional perovskites Cs 4 PbI 6 for protection in addition to already robust SiO 2 all-inorganic encapsulation, via high-temperature solid-state synthesis. It is proven that the CsPbI 3 –Cs 4 PbI 6 nano-composite not only maintains the emission peak location of CsPbI 3 PeNCs at 700 nm with remarkable oxygen and water resistances, but also exhibits enhanced instant and long-term thermal stability compared with samples containing less amount of Cs 4 PbI 6 . The passivation of defects on the interface of CsPbI 3 –Cs 4 PbI 6 contributes to the enhancement of photoluminescence quantum yield by 8%. These ultra stable CsPbI 3 –Cs 4 PbI 6 nano-composites show potentials in the application of luminous and display industries.
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CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Dingming Yu,Lifang Liu,Bin Ding,Jianyong Yu,Yang Si
Water-borne pathogenic diseases significantly threaten human health and the global economy, and traditional water disinfection strategies such as chlorination or membrane filtration to remove pathogens still suffer from harmful byproducts, biofouling, and limited handling capacity. Here, a bottom-up strategy is reported to develop biomimetic nanofibrous aerogels with superelastic and conductive networks by assembling Ag nanowires in a 3D SiO 2 nanofibrous skeleton via freeze-drying method for safe and efficient water disinfection. Inspired by the prey capture behavior of spiders using their webs, the core of this design is constructing spanning and interconnected networks with millions of conductive nanotips, which could inactivate microbes instantaneously based on the synergistic effect of interception and electroporation. Benefitting from the high porosity (99.81 %), superelasticity, and robust structural stability of the resultant aerogels, an electroporation-disinfection device (EDD) equipped with aerogels exhibits superior bactericidal (>99.9999 %) and virucidal (>99.9 %) performances at low derive voltage (1 V) and high flux (9900 L m −2 h −1 ) with energy consumption of 0.83 Wh m −3 . This novel disinfection method provides new insights into practical water treatment in an efficient, environmental, and sustainable way.
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MOLECULES
·
2023
·Vol. 28
·期 2
·662
·
IF 4.6
Xiaoyan Ran,Ping Guo,Caifang Liu,Yulan Zhu,Cheng Liu,Bangjin Wang,Junhui Zhang,Shengming Xie,Liming Yuan
The chiral covalent-organic framework (CCOF) is a new kind of chiral porous material, which has been broadly applied in many fields owing to its high porosity, regular pores, and structural adjustability. However, conventional CCOF particles have the characteristics of irregular morphology and inhomogeneous particle size distribution, which lead to difficulties in fabricating chromatographic columns and high column backpressure when the pure CCOFs particles are directly used as the HPLC stationary phases. Herein, we used an in situ growth strategy to prepare core–shell composite by immobilizing MDI-β-CD-modified COF on the surface of SiO2-NH2. The synthesized MDI-β-CD-modified COF@SiO2was utilized as a novel chiral stationary phase (CSP) to explore its enantiomeric-separation performance in HPLC. The separation of racemates and positional isomers on MDI-β-CD-modified COF@SiO2-packed column (column A) utilizing n-hexane/isopropanol as the mobile phase was investigated. The results demonstrated that column A displayed remarkable separation ability for racemic compounds and positional isomers with good reproducibility and stability. By comparing the MDI-β-CD-modified COF@SiO2-packed column (column A) with commercial Chiralpak AD-H column and the previously reported β-CD-COF@SiO2-packed column (column B), the chiral recognition ability of column A can be complementary to that of Chiralpak AD-H column and column B. The relative standard deviations (RSDs) of the retention time and peak area for the separation of 1,2-bis(4-fluorophenyl)-2-hydroxyethanone were 0.28% and 0.79%, respectively. Hence, the synthesis of CCOFs@SiO2core–shell composites as the CSPs for chromatographic separation has significant research potential and application prospects.Keywords:chiral covalent-organic frameworks;core–shell composites;high-performance liquid chromatography;chiral separation
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