Materials
·
2022
·Vol. 16
·期 1
·201
·
IF 3.748
Luping Tang,Chen Liao,Yingqing Guo,Yangyang Zhang
Metal nanoparticles have attracted a great deal of interest due to their unique properties of surface plasmon resonance. Metal nanoparticles can enhance the fluorescence emission intensity of quantum dots (QDs) through the local surface plasmon resonance effect, which is mainly determined by the distance between them. Therefore, it is very important to achieve controllable distance between metal and QDs, and study fluorescence enhancement. In this work, the controllable adjustment of the distance between metal nanoparticles and QDs was successfully realized by controlling the thickness of the SiO2shell of Ag@SiO2nanoparticles. Firstly, Ag nanoparticles with uniform size distribution and relatively high concentration were prepared, and then the thickness of the SiO2shell was controlled by controlling the amount of tetra-ethyl orthosilicate (TEOS) in the hydrolysis of TEOS reaction. (3-aminopropyl) triethoxysilane (APS) was used to connect CdS/ZnS QDs with Ag@SiO2nanoparticles to form Ag@SiO2@CdS/ZnS QD composite nanoparticles. The fluorescence spectra shows that the fluorescence intensity of the Ag@SiO2@CdS/ZnS QD composite nanoparticles is significantly enhanced. Photoexcitation spectra and fluorescence spectra of CdS/ZnS QD and Ag@SiO2@CdS/ZnS QD composite nanoparticles, measured under different energy excitation conditions, indicate that the existence of Ag nanoparticles can enhance the fluorescence intensity of CdS/ZnS QDs. Finally, a further physical mechanism of fluorescence enhancement is revealed.Keywords:Ag-SiO2;fluorescence enhancement;transmission electron microscope;quantum dots;photoexcitation spectra
研究领域:
材料科学
·
光学
·
纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY
·
2017
·Vol. 17
·期 12
·8818-8826
·
IF 1.483
Liu Jingwei,Huo Minfeng,Zhu Yan
Mn–Na2WO4/SiO2 synthesized by Urea-assisted hydrothermal-Impregnation route has more and stronger surface basic sites, and more surface lattice oxygen, leading to higher methane conversion with higher selectivity toward ethane and ethylene in oxidative
coupling of methane reaction, compared to Mn–Na2WO4/SiO2 produced by Co-precipitation-Impregnation (CPI) and Sequential Impregnation (SI) methods.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
KEY ENGINEERING MATERIALS
·
2018
·
IF 0
Wu Lei,Ben Ma,Jian Pu,Chi Bo,Li Jian
As the ceramic substrate materials in automobile oxygen sensor, 5YSZ/Al2O3 matrix composite ceramic with different amount of silica are prepared by ball-milling,tape casting and sintering.They are investigated for their microstructure and mechanical properties.The microstructure of the sample is analyzed by Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX).Fracture strength is measured by ring-on-ring method. It is found that adding 1 wt.% SiO2 into 5YSZ/Al2O3 matrix can improve the strength of composite ceramics.
研究领域:
材料科学
·
机械工程
✓ 已验证
产品关联
DOI
PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION
·
2017
·Vol. 34
·期 7
·1700117
·
IF 4.474
Yanning Qu,Renliang Huang,Wei Qi,Qi Qu,Rongxin Su,Zhimin He
Encapsulation of enzymes with enhanced activity and recyclability in water-in-oil Pickering emulsions is a simple and efficient method for their immobilization; however, the effect produced by the structure of colloidal particles on the stabilization of the Pickering emulsion for enzyme catalysis has not been investigated in detail. In this study, four types of hydrophobic Fe 3 O 4 @SiO 2 nanoparticles (NPs) with similar chemical compositions, particle diameters, but different surface characteristics have been prepared and utilized for enzyme encapsulation in various water-in-oil magnetic Pickering emulsions, after which the relationship between NPs structure, size of emulsions droplets, and enzyme activity is examined. The obtained results indicate that (i) the more hydrophobic Fe 3 O 4 @SiO 2 NPs cause the higher enzyme activity; (ii) the higher hydrophobicity of oil phase also increases the enzyme activity, especially for Fe 3 O 4 @w-SiO 2 NPs which form in the solvent of water. The results are mainly attributed to the higher specific surface area of emulsion droplets and interfacial mass transfer of substrates through the interfaces of droplets. The reported data provide new insights into the mechanism of stabilization of Pickering emulsions for enhancing enzyme activity and demonstrate efficient theoretical references for enzyme immobilization and synthesis of stable and active biocatalysts with high recyclability.
研究领域:
生物化学
·
材料科学
·
酶工程
✓ 已验证
产品关联
DOI
高影响因子
SUPERLATTICES AND MICROSTRUCTURES
·
2014
·
IF 1.979
Hongbo Tang,Yuchang Su,Jiang Tan,Te Hu,Jinyu Gong,Lihua Xiao
In this work, LaB 6 @SiO 2 nanoparticle with a core–shell structure was synthesized and doped into Poly(vinyl butyral) (PVB) matrix to prepare LaB 6 @SiO 2 –PVB nanocomposite film. Field emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and ultraviolet–visible–near infrared spectroscopy (UV–vis–NIR) were employed to characterize these materials. The TGA and UV–vis–NIR results show that LaB 6 @SiO 2 nanoparticle contributed to improving thermal stability of PVB in LaB 6 @SiO 2 –PVB film, with an increase of almost 60 °C from the initial decomposition temperature in the case of the neat PVB film; additionally, maximum transmittance in visible region red-shifted from 605 to 645 nm and maximum absorption in near-infrared region moved slightly from 1466 to 1472 nm. In short, the LaB 6 @SiO 2 NPs could be a potential candidate for transparent and heat insulation materials.
研究领域:
材料科学
·
纳米技术
·
光学工程
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2015
·Vol. 5
·期 126
·103982-103988
·
IF 3.84
Zheng Han,Xiang Li,Minhua Zhang,Zongzhang Liu,Meixiang Gao
A series of ZrO2–SiO2 catalysts synthesized by sol–gel method were investigated for the 1,3-butadiene formation from bioethanol and acetaldehyde. The influence of ZrO2 content and reaction conditions on catalytic performance were studied. The catalysts were characterized by N2 adsorption–desorption analysis, temperature-programmed desorption of NH3 (NH3-TPD), IR spectroscopy of adsorbed pyridine (Py-IR), Fourier Transform Infrared Resonance (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscope (TEM). These characterization results indicated that suitable intensity of acid sites, especially Lewis acid, are very crucial to obtain an active catalyst. The catalysts showed significantly higher selectivity for C4 chemicals, and 2 wt% ZrO2 content reached the highest selectivity to BD (69.7%), at space velocity (WHSV) of 1.8 h−1.
研究领域:
催化化学
·
可再生资源转化
·
材料科学
✓ 已验证
DOI
高影响因子
ChemistrySelect
·
2022
·Vol. 7
·期 47
·e202200923
·
IF 2.307
Qi Peiyao,Wang Shuo,Ju Ye,Tang Zhongli,Qu Jin,Zheng Junping,Liu Xiaofei
Graphical SiO 2 /PAM composite nanospheres were synthesized by the inverse microemulsion method to meet the needs of profile control and water shutoff in oilfields. The structure, oil displacement effect and rheological properties of polyacrylamide nanospheres and SiO 2 /PAM composite nanospheres were comparatively studied. This work provides a basis for the practical application of SiO 2 /PAM composite nanospheres in oilfields. Polyacrylamide nanospheres are a kind of polymer material that can improve the development effect of oilfield water flooding and realize reservoir stimulation. However, due to its good water absorption, the strength cannot well meet the needs of practical production, and is forced to be limited to application on oil displacement. Therefore, in this paper, SiO 2 /PAM composite nanospheres were synthesized by the inverse microemulsion method to meet the needs of profile control and water shutoff in oilfields. The structure, oil displacement effect and rheological properties of polyacrylamide nanospheres and SiO 2 /PAM composite nanospheres were comparatively studied. The results show that both nanospheres are viscoelastic nanospheres. Since the elastic response is greater than the viscous response in SiO 2 /PAM composite nanospheres, and the polymer nanospheres do the opposite, there are significant differences in various rheological properties, such as variation of apparent viscosity with shear rate, creep recovery characteristics, viscoelasticity etc. This work provides a basis for the practical application of SiO 2 /PAM composite nanospheres in oilfields.
研究领域:
石油工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CATALYSIS
·
2024
·
IF 6.5
Ruoyuan Li,Aixia Li,Junhua Li,Yao Wang,Zhiming Liu
Selective catalytic reduction of NO x by CO (CO-SCR) in the presence of O 2 is challenging because in this process CO is prone to being oxidized by O 2 , thus inhibiting NO x reduction by CO. Furthermore, SO 2 typically leads to the deactivation of the CO-SCR catalyst. Herein, a significant promoting effect of SO 2 on Ir/SiO 2 catalyst for the CO-SCR of NO x in the presence of O 2 is reported. In-situ X-ray Absorption Fine Structure (XAFS) and X-ray photoelectron spectroscopy (XPS) analysis showed that SO 2 does not affect the chemical nature of Ir 0 under reaction conditions. However, SO 2 can be oxidized to sulfate and deposit on the catalyst surface. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis demonstrated that the presence of SO 2 can inhibit the CO + O 2 reaction, thus leaving more CO available to reduce NO x over the active Ir 0 sites. As a result, the reduction of NO x is remarkably promoted even in the presence of O 2 and SO 2 .
研究领域:
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
Science of Advanced Materials
·
2019
·Vol. 11
·期 12
·1816-1824
·
IF 1.158
Qin Huihao,Zhang Wei,Luo Yi,Wei Yubo,Sun Shenglu,Chen Jingya
Polylactic acid glycolic acid (PLGA), a polymer material, is used as a shell and perfluorooctane (PFOB) as the core. Fe3O4@SiO2 nanoparticles are distributed in the shell to prepare a magnetic phase change multifunctional nano emulsion contrast agent
(Fe3O4@SiO2/PLGA/PFOB). The ultrasound, magnetic resonance imaging and CT imaging effects of the contrast agent on normal rat liver parenchyma are investigated. Methods: Single emulsification method is used to prepare Fe3O4@SiO2-loaded
polymer Fe3O4@SiO2/PLGA/PFOB nanoparticles encapsulated with PLGA. In addition, polymer Fe3O4@SiO2/PLGA nanoparticles loaded with Fe3O4@SiO2 nanoparticles, PLGA@PFOB nanoparticles coated with
PLGA and blank PLGA nanoparticles are prepared as experimental control group. Its surface morphology, internal structure, particle size, potential and other general characteristics are tested. RAW264.7 mouse mononuclear macrophages are cultured in vitro. Prussian blue staining is used
to observe macrophage phagocytosis after Fe3O4@SiO2/PLGA/PFOB contrast agent is added to incubate for 3 hours. MTT method is used to detect the effect of contrast agent on cell activity. The macrophage suspension engulfed with Fe3O4-PFOB
is examined by ultrasound, magnetic resonance and CT. The results showed that Fe3O4@SiO2/PLGA/PFOB is brown emulsion after being dissolved in double distilled water. Under the light microscope and scanning electron microscope, Fe3O4@SiO2/PLGA/PFOB
is spherical, with regular shape, uniform size, good dispersity and smooth surface. Macrophages are dependent on the phagocytosis of the contrast medium without affecting the activity of macrophages. Moreover, in vitro imaging experiments, compared with the control group, macrophages
phagocytized by Fe3O4@SiO2/PLGA/PFOB have obvious enhancement effects in ultrasound, magnetic resonance and CT imaging. In conclusion, Fe3O4@SiO2/PLGA/PFOB has good stability in vivo, can be engulfed by liver macrophages,
and can enhance ultrasound, magnetic resonance and CT imaging of liver parenchyma. It is a safe and effective multifunctional ultrasound contrast agent.
研究领域:
医学影像学
·
材料科学
·
生物医学工程
✓ 已验证
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2018
·
IF 8.097
Ebrahim Ataeivarjovi,Zhigang Tang,Jian Chen
In this present work, a novel approach has been proposed by which a solvent absorption and membrane desorption methods can significantly reduce the carbon dioxide (CO2) emission and energy consumption. In this method, the CO2 capture processing is based on the combination of membrane and physical solvent. Here, dimethyl carbonate and polydimethylsiloxane (PDMS)–SiO2 nanocomposite were used as the physical solvent and desorption membrane, respectively. However, the main focus of this research was on the CO2 desorption behavior of PDMS–SiO2 hybrid membrane. To do so, the influence of the operating conditions and membrane properties on the pervaporation process to capture CO2 have been investigated. The PDMS–SiO2 hybrid membrane containing 10 wt % SiO2 was the most effective membrane. Results revealed that increase in CO2 concentration from 1.5 to 3 wt % led to decrease in the selectivity from 94 to 47 and increase in flux from 1.7 to 5.38 (kg/m2·h). In addition, an increase in temperature increased the flux and reached the highest level (8.17 kg/m2·h) at 40 °C. However, the selectivity decreased to 36.13. It was found that the addition of SiO2 nanoparticles to the PDMS membrane not only enhanced the membrane performance but also decreased the energy consumption about 75% compared with gas stripping method and mass transfer about 49% compared with pure PDMS membrane. Finally, these results illustrated that such a novel technique used for pervaporation separation process is a green and promising alternative to separate CO2 from the physical solvent.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2014
·Vol. 4
·期 86
·45920-45929
·
IF 3.708
Lisha Tan,Jiang Xu,Xiaoqin Xue,Zimo Lou,Jin Zhu,Shams Ali Baig,Xinhua Xu
Silica-coated magnetite (Fe3O4@SiO2) nanoparticles functionalized with amino, imino and sulfonic groups (Fe3O4@SiO2–mPD/SP) were successfully synthesized via a facile chemical oxidative polymerization of m-phenylenediamine (mPD) and m-sulfophenylenediamine-4-sulfonic acid (SP) monomers, and utilized for selective removal of Pb(II) and Cr(VI) from aqueous solutions. It was revealed by the characterizations that the polymers formed on Fe3O4@SiO2 nanoparticles were the true copolymers with a mPD–SP unit, rather than a mixture of mPD and SP homopolymers. Fe3O4@SiO2–mPD/SP nanocomposites could be easily separated from aqueous solutions within 30 s. The maximum adsorption capacities of Pb(II) (83.23 mg g−1) and Cr(VI) (119.06 mg g−1) on Fe3O4@SiO2–mPD/SP nanocomposites were obtained at the mPD/SP molar ratios of 95 : 5 and 50 : 50, respectively. Moreover, satisfactory selective removal of Pb(II) and Cr(VI) from their mixtures with Cu(II) and Ni(II) ions were exhibited by the Fe3O4@SiO2–mPD/SP (95 : 5) and Fe3O4@SiO2–mPD/SP (50 : 50), respectively. The Pb(II) adsorption equilibrium was reached within 5 min by Fe3O4@SiO2–mPD/SP (95 : 5). The adsorption data of Pb(II) and Cr(VI) were both fitted well to the Freundlich isotherm and followed the pseudo-second-order kinetic model. The adsorption mechanism of Pb(II) and Cr(VI) on Fe3O4@SiO2–mPD/SP nanocomposites included five processes, namely: ion-exchange, complexation adsorption, reduction reaction, electrostatic attraction and physical adsorption. The enhanced adsorption performance of nanoparticle-based magnetic adsorbents for selective removal of heavy metal ions can be achieved with such a copolymerization strategy.
研究领域:
环境科学
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
ELECTROCHIMICA ACTA
·
2018
·
IF 5.116
Yiming Zhao,Lihua Zheng,Hao Wu,Huan Chen,Liwei Su,Lianbang Wang,Yuanhao Wang,Manman Ren
Tetravalent Si materials (SiO 2 and transition metal silicates) are receiving tremendous attentions for lithium storage, whereas a troublesome problem is how to improve the content of active Si. This work reports a novel method to boost their lithium storage capabilities by using highly-dispersed Co element in the form of nanofilm-like Co 2 SiO 4 /SiO 2 powder on the surface of reduced graphene oxide (RGO) that promotes the electronic diffusion and accommodates the volume changes. As a result, the Co 2 SiO 4 /SiO 2 /RGO exhibits over 20 times higher reversible capacity and better rate performance than the SiO 2 /RGO counterpart. In comparison, the Co 2 SiO 4 /SiO 2 /RGO shows the highest reversible capacity (1382 mAh g −1 at 500 mA g −1 ) and longest life span (500 cycles) in all known silicates-based materials and higher power/energy density than both of commercial graphite and Li 4 Ti 5 O 12 materials. Ex-situ X-ray photoelectron spectra and electrochemical tests at different voltage windows are conducted to illustrate the reason for the significantly improved performances. It demonstrates that tetravalent Si is gradually activated to lower-valence form by highly-dispersed Co generated with cycling. This observation provides new evidence for the electrochemical catalytic mechanism in transition metal silicates for lithium storage.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）