ELECTROCHIMICA ACTA
·
2018
·
IF 5.116
Nian Cao,Peng Zeng,Faqiong Zhao,Baizhao Zeng
A solid-state electrochemiluminescence (ECL) sensor for the highly selective and sensitive detection of 17β-estradiol (E2) is presented. The sensor is constructed with Ru(bpy) 3 2+ doped vinyl-SiO 2 nanoparticles (Ru@ethyl-SiO 2 ) and E2 imprinted polypyrrole (MIP). The Ru@ethyl-SiO 2 nanoparticles act as luminophores, while the MIP provides recognition sites for E2. As the adsorbed template molecules can act as co-reactant for Ru@ethyl-SiO 2 , the ECL intensity increases with the adsorption amount of E2 rising, which depends on its concentration in the solution. Owing to the well combination/or synergy of the smart MIP and the high-effective ECL material, the resulting sensor exhibits highly selective and ultrasensitive response to E2. Under the selected conditions, the ECL intensity increment (Δ I ) is linear to the logarithm of E2 concentration over the range from 0.01 to 100 pg mL −1 , and the detection limit is down to 0.005 pg mL −1 (S/N = 3). The ECL sensor also shows good reproducibility and repeatability. It has been successfully applied to the detection of E2 in tea and oral solution samples and the recoveries are 87.7%–115.3%.
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Russian Journal of Physical Chemistry A
·
2019
·Vol. 93
·期 6
·1128-1132
·
IF 0.581
Xuqiang Ji,Niu Yusheng,Xu Yuanhong
Abstract The design and development of excellent microwave absorption (MA) material is significant for healthcare, electronic, and security industries. Herein, a sophisticated composite with the advantages of large interlayer space, nanoparticles with small size, and hierarchical nanostructure (core@shell@void@shell configuration) simultaneously is demonstrated for the first time. Such unique SiO 2 @TiO 2 nanoparticle was fabricated via a multi-step process. Associating maximum reflection loss value can reach –35.2 dB in certain frequency of 11 GHz and thickness of 3.0 mm. Small-sized TiO 2 nanoparticles (about 6 nm) in first coating and large gap between TiO 2 coating layers are significantly critical for the superior MA performance. Our work points a new direction to rationally construct high-performance microwave absorber.
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Materials
·
2018
·Vol. 11
·期 11
·2067
·
IF 2.467
Weihong Huang,Yujie Qing,Ningwei Wang,Yi Lu,Tianshu Liu,Tao Liu,Wenming Yang,Songjun Li
In this research, a novel, sulfamethazine, thermosensitive, molecularly-imprinted polymer (MIP) with an obvious core–shell structure for the enrichment of sulfamethazine (SMZ), which involved temperature sensitive monomer N-Isopropylacrylamide, functional monomer methacrylic acid and cross-linking agents ethyleneglycol dimethacrylate (EGDMA) and N,N′-methylenebisacrylamide, was successfully compounded using the surface polymerization method. To ensure the best experimental group, we designed and compared three groups of controlled experiments of MIPs with different crosslinking agents. When the adsorption temperature was almost the lower critical solution temperature (LCST) of Poly(N-Isopropylacrylamide), the preparative MIPs showed outstanding adsorption capacity and specific identification to sulfamethazine. Moreover, this allowed the MIPs to better facilitate by combining the template molecules, as well as optimizing the imprinting factor. In addition, after 80 min, the adsorption of the MIPs leveled off and remained constant, and the adsorption quantity reached (a maximum of) at 8.1 mg·g−1.Keywords:thermosensitive molecularly imprinted polymers;surface imprinting;sulfamethazine
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Physica Status Solidi-Rapid Research Letters
·
2018
·Vol. 12
·期 10
·1800319
·
IF 3.721
Bismark Boateng,Gaolong Zhu,Weiqiang Lv,Dongjiang Chen,Chao Feng,Muhammad Waqas,Shamshad Ali,Kechun Wen,Weidong He
A highly uniform, heterogeneous-phase composite separator is synthesized by a direct post-solidation process from the mixture of nano-SiO 2 /acetone monodisperse suspension and poly(vinylidene fluoride- co -hexafluoropropylene) (PVDF- co -HFP)/acetone gel, without any organic surfactants. This technique leads to the PVDF- co -HFP/SiO 2 composite separator outstanding microstructural uniformity. The incorporation of SiO 2 nanoparticles leads to reduced crystallinity (≈27%), enhanced wettability (≈14%), improved electrolyte uptake (≈420%), and enhanced mechanical strength (>14 MPa) of the composite separator. These enhanced properties of the separator translate into remarkable LiFePO 4 /Li battery performance with reduced polarization, a high room-temperature capacity of 165 mAh g −1 at 0.5 C, a high thermal dimensional stability (≈4.5% shrinkage after annealing at 160 °C for 1 h) and 5.2% capacity degradation after 1500 charge/discharge cycles at 2 C.
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Journal of Physical Chemistry C
·
2013
·
IF 4.814
Yibo Hu,Kai Tao,Chunzheng Wu,Chen Zhou,Hongfeng Yin,Shenghu Zhou
Pd@SiO2 core–shell nanoparticles were successfully synthesized by a sol–gel method. Tetradecyl trimethyl ammonium bromide capped Pd nanoparticles were coated with SiO2 through the hydrolysis of tetraethylorthosilicate. The as-synthesized Pd@SiO2 particles consist of Pd cores with a particle size of 3.7 nm and SiO2 shells with a thickness from 10 to 30 nm at different synthetic conditions. The Pd@SiO2 nanocatalysts with 1.9–2.4 nm mesoporous SiO2 shells were generated after removal of tetradecyl trimethyl ammonium bromide from Pd@SiO2 core–shell particles by calcination and following H2 reduction. The relevant characterizations such as XRD, TEM, FT-IR, and BET were carried out for Pd@SiO2 particles, and the results showed that the Pd@SiO2 nanocatalysts were highly stable with the protection of silica shells, and the Pd cores did not increase during thermal treatment and H2 reduction. The studies of catalytic CO oxidation at high temperatures and hydrogenation of nitrobenzene with H2 were tested for Pd@SiO2 nanocatalysts, and the results indicated that Pd@SiO2 nanocatalysts were stable at high temperatures and highly active and stable for hydrogenation of nitrobenzene even after long time use.
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CHEMICAL ENGINEERING JOURNAL
·
2012
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IF 3.461
Jianming Zhang,Shangru Zhai,Shi Li,Zuoyi Xiao,Yu Song,Qingda An,Ge Tian
Contamination of natural water with heavy metals (especially lead ions) is a problem of major concern and thus great demand of effective adsorbents for removal of toxic ions is increasing. Due to the task-specific properties of amino groups, core–shell nanostructures of Fe 3 O 4 @SiO 2 –NH 2 have been extensively investigated as advanced adsorbents; however, most studies on surface modification of Fe 3 O 4 @SiO 2 substances were of environmentally inefficient grafting methods. Herein, we demonstrated that mono-dispersed and spherical Fe 3 O 4 @SiO 2 –NH 2 nanomaterials can be facilely prepared by co-condensation of TEOS with APTMS employing a green sol–gel process. The as-prepared Fe 3 O 4 @SiO 2 –NH 2 magnetic nanoparticles (MNPs) prepared under optimum conditions possessing uniform core–shell structure (∼200 nm in diameter), relatively high loading of amino-functionality (∼5.45 wt%), easy recovery by external magnet and effective removal of Pb(II) ( q m = 243.9 mg/g, 25 °C). The adsorption was shown to be effective and a higher temperature was more favorable for the adsorption. The adsorption equilibrium data obeyed the Langmuir model and the kinetic data were well fitted to the pseudo-second-order model. Thermodynamic studies revealed the feasibility and endothermic nature of the system. These results demonstrated that the sol–gel produced Fe 3 O 4 @SiO 2 –NH 2 , due to its easy synthesis and recovery and eco-friendliness, can be a potential adsorbent for Pb(II) removal.
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JOURNAL OF NANOPARTICLE RESEARCH
·
2014
·Vol. 16
·期 11
·1-10
·
IF 2.278
Yao Yang Rong,Huang Wan Zhen,Zhou Huan,Cui Xia,Zheng Yi Fan,Song Xu Chun
A core–shell nanostructured magnetic photocatalyst Fe 3 O 4 @SiO 2 @Ag 3 PO 4 with a grain size ranging from 200 to 400 nm was prepared via a facile and effective method. The as-prepared products were characterized using X-ray diffraction, high-angle annular dark field-scanning transmission electron microscopy, energy-dispersive spectroscopy, and UV–Vis diffuse reflectance spectra. The photocatalytic activity was evaluated by the degradation of 10 −5 M RhB solution under visible light irradiation with a cut-off filter ( λ ≥ 420 nm). The results showed that nearly 100 % color removal efficiency was achieved in 45 min with the presence of Fe 3 O 4 @SiO 2 @Ag 3 PO 4 photocatalyst. Furthermore, it can be easily recollected from the solution by magnetic separation and efficiently recycled without major loss of activity due to its superior magnetic responsibility and extremely high reusability, exhibiting highly potential applications in water purification avoiding the secondary pollution.
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JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
·
2014
·Vol. 90
·期 3
·407-414
·
IF 2.494
Xiangye Li,Ruting Chen,Shouhong Xu,Honglai Liu,Ying Hu
BACKGROUND Injectable polymer gels for tissue engineering offer specific advantages over preformed scaffolds. They can transform from a sol to a block gel as a response to an external stimulus. One effective strategy for improving the mechanical strength of a gel is to introduce an inorganic material. RESULTS Microparticles composed of a hard SiO 2 core covered with a thermoresponsive hybrid gel (sodium hyaluronate/poly( N -isopropylacrylamide); NaHA/PNIPAm) were synthesized. The microparticles were characterized by dynamic light-scattering and transmission electron microscopy; rheological measurements were also performed. The microparticles were perfectly spherical and had a core–shell structure. They can perform a sol–gel transformation, that is, they shrank and assembled to form a macroscopic hydrogel through physical cross-linking at the gelation temperature ( T gel ), which was determined by rheological measurements. The T gel was adjusted by changing the concentration of microparticles or Ca 2+ ions. CONCLUSION The introduction of NaHA and SiO 2 improved the mechanical properties of the macroscopic gels. The rigidity and stability of the macroscopic gel were controlled by the molecular weight of NaHA and the amount of PNIPAm. Such injectable hydrogels might have potential as scaffold biomaterials, and are expected to be the ‘ink’ for three-dimensional bioprinters. © 2014 Society of Chemical Industry
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Journal of Materials Chemistry A
·
2014
·Vol. 2
·期 43
·18246-18255
·
IF 0
Liang Huang,Pengli Zhu,Gang Li,Daoqiang (Daniel) Lu,Rong Sun,Chingping Wong
Reduced graphene oxide (RGO)-encapsulated SiO2 hybrids (SiO2@RGO) were fabricated from the thermal reduction of electrostatically assembled SiO2@GO hybrids. Then, epoxy composites, filled with SiO2, SiO2@GO and SiO2@RGO hybrids, were prepared by a solvent-free curing process, and their thermal, dielectric and thermo-mechanical properties were investigated and compared. In the SiO2@RGO/epoxy composites, the mono-dispersed SiO2 nanoparticles are firmly embedded in the thin layer of RGO nanosheets, forming unique core–shell nanostructures that effectively prevent the aggregation of RGO nanosheets in the polymer matrix, construct conductive pathways at the particle–polymer interface and afford the epoxy composites with outstanding thermo-mechanical properties. The dielectric properties of the SiO2@RGO/epoxy composites exhibit a typical percolation transition near 0.174 vol% for RGO (20 wt% of SiO2@RGO hybrids), where the dielectric constant could reach 77.23 at 1 kHz, which is 22 times that of the neat epoxy resin. Upon further increase of the loading content, the gradual contact of the filler particles leads to the formation of interfacial continuous conductive networks, and both the thermal conductivity and dielectric constant of the composites show a dramatic increase. With a filler loading of 40 wt% SiO2@RGO (0.373 vol% for RGO), a thermal conductivity of 0.452 W m−1 K−1 is obtained, which is two times larger than that of neat epoxy. In addition, SiO2@RGO/epoxy composites reveal significantly decreased coefficient of thermal expansion (CTE) and increased glass transition temperature (Tg). We believe this special core–shell SiO2@RGO structure, with its inner mechanically enhanced inorganic particles and outer interfacial conductive phase, could make full use of the enhancement effect of different components and thus endow the polymer composites with outstanding properties overall.
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BIOINORGANIC CHEMISTRY AND APPLICATIONS
·
2015
·
IF 2.081
Zeyu Guan,Jinquan Wan,Yongwen Ma,Yan Wang,Yajie Shu
A novel amino-functionalized silica-coated nanoscale zerovalent iron (NZVI@SiO2-NH2) was successfully synthesized by using one-step liquid-phase method with the surface functionalization of nanoscale zerovalent iron (NZVI) to enhance degradation of chlorinated organic contaminants from anaerobic microbial system. NZVI@SiO2-NH2 nanoparticles were synthesized under optimal conditions with the uniform core-shell structure (80–100 nm), high loading of amino functionality (~0.9 wt%), and relatively large specific surface area (126.3 m2/g). The result demonstrated that well-dispersed NZVI@SiO2-NH2 nanoparticle with nFe0-core and amino-functional silicon shell can effectively remove 2,4,6-trichlorophenol (2,4,6-TCP) in the neutral condition, much higher than that of NZVI. Besides, the surface-modified nanoparticles (NZVI@SiO2-NH2) in anaerobic granule sludge system also showed a positive effect to promote anaerobic biodechlorination system. More than 94.6% of 2,4,6-TCP was removed from the combined NZVI@SiO2-NH2-anaerobic granular sludge system during the anaerobic dechlorination processes. Moreover, adding the appropriate concentration of NZVI@SiO2-NH2 in anaerobic granular sludge treatment system can decrease the toxicity of 2,4,6-TCP to anaerobic microorganisms and improved the cumulative amount of methane production and electron transport system activity. The results from this study clearly demonstrated that the NZVI@SiO2-NH2/anaerobic granular sludge system could become an effective and promising technology for the removal of chlorophenols in industrial wastewater.
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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.
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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.
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