RSC Advances
·
2016
·Vol. 6
·期 92
·89221-89230
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IF 3.289
Jing Hong,Changhua Liu,Xi Deng,Ting Jiang,Lin Gan,Jin Huang
SiO2 coated with graphene oxide (GO) hybrids (SiO2@GO) were fabricated by electrostatic self-assembly and introduced into an epoxy polymer (EP) matrix to prepare epoxy composites by a solvent-free curing process. The thermal stability, mechanical properties and tribological behavior of SiO2@GO/EP composites were investigated and compared. It was found that the epoxy composites with the aligned core–shell structure of SiO2@GO improved the thermal stability, as well as excellent mechanical and tribological properties. The low content 0.5 wt% SiO2@GO/EP nanocomposites exhibited nearly 88.4% reduction in the friction coefficient and several orders of magnitude reduction in wear rate, constituting a potential breakthrough for future tribological applications. Compared with unfilled epoxy polymers or epoxy polymers with unmodified fillers, the major increase in the tribological properties of the SiO2@GO/EP composites shows the synergy effect between nano-SiO2 and GO during the wear process. The behavior of nano-SiO2 and GO were probably mostly due to ball-bearing and an ultrathin lamellar effect, respectively. The obtained results indicate that the core–shell structure of SiO2@GO as a more effective synergistic system is a valid method for greatly improving the friction and wear properties and mechanical properties of resin-based composites.
研究领域:
材料科学
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复合材料工程
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产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2015
·
IF 2.605
Yao Shi,Xiao-Liang Zhang,Gang Feng,Xiangshu Chen,Zhang-Hui Lu
Ag–SiO 2 nanocomposites (NCs) with “plum-pudding” structure have been synthesized using a facile reverse micelle method. The as-synthesized Ag–SiO 2 NCs were calcined at 623 K to remove the surfactants and then characterized by XRD , FE-SEM, TEM, EDX, ICP and N 2 adsorption–desorption. The obtained results demonstrated that many ultrafine Ag nanoparticles (NPs) with size of ~2 nm are well dispersed in each SiO 2 nanosphere (28 nm). In comparison with free Ag NPs and SiO 2 supported Ag NPs, the Ag–SiO 2 NCs exhibited a better catalytic activity for the reduction of 4-nitrophenol with a turnover frequency of 489 h −1 at room temperature. Ag–SiO 2 NCs also displayed a superior catalytic activity for hydrogenation of 2-NP and 3-NP. The activation energy of Ag–SiO 2 NCs was estimated to be about 34.4 kJ mol −1 , which was lower than most of the reported values for the same reaction using Ag-based catalysts, indicating the superior catalytic performance of these plum-pudding structured catalysts.
研究领域:
材料科学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Advanced Dielectrics
·
2019
·
IF 0
Bing Xie,Ling Zhang,Mohsin Ali Marwat,Yiwei Zhu,Weigang Ma,Pengyuan Fan,Haibo Zhang
The development of advanced dielectric film materials with high energy storage performance is of critical significance for pulsed power capacitor applications. Nevertheless, the low discharged energy density ( U e ) of current dielectric film material restricts their further application. In this work, core-shell structured SrTiO 3 @SiO 2 nanowires (ST@SiO 2 NWs) fillers are fabricated based on interface engineering for high U e . The optimized SiO 2 insulating layer could effectively confine the mobility of space charge carriers in the interfacial zone between ST NWs and thick SiO 2 insulating layer, thus reducing the interfacial polarization between the interface of nanofillers/polymer, which could be used to optimize the electric field strength and electric displacement of the corresponding nanocomposite. As a result, this nanocomposite film simultaneously exhibits enhanced maximum applied electric field ( E max ) and ( D max - P r ) values, thus releasing an ultrahigh discharged energy density of 14.7 J/cm 3 at 390 MV/m, which is 99% higher than that of the conventional ST/P(VDF-CTFE) (without SiO 2 coating) nanocomposite, and it is almost 2.5 times that of pure P(VDF-CTFE). This work demonstrates the superiority of the core-shell structured paraelectric nanowire in enhancing the energy storage performance of dielectric film capacitors, which is expected to guide the design of advanced energy-storage nanocomposites.
研究领域:
材料科学
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能源存储
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产品关联
DOI
CONSTRUCTION AND BUILDING MATERIALS
·
2022
·
IF 7.693
Qiang Gao,Xiaomei Wu,Fangya Shi
In recent years, cool building materials have received increasing attentions due to their superior energy-saving efficiencies. In this work, novel self-cleaning cool coatings based on fluorocarbon resin-montmorillonite (MMT)/SiO 2 composites were prepared for energy-saving buildings. The intercalation modification of MMT improved the dispersion stability of MMT in organic solvent. Surface modification of MMT and SiO 2 particles by fluoroalkyl silane (FAS) produced hydrophobic particles. Fluorocarbon resin was used as a binder. With the assistance of the micro/nano structure of montmorillonite/SiO 2 composites and low surface energy of FAS and fluorocarbon resin, superhydrophobic state of the MMT/SiO 2 composite coatings can be achieved. The maximum contact angle of the MMT/SiO 2 composite coatings was as high as 163.5°. The superhydrophobic composite coatings exhibited superior self-cleaning property and good mechanical durability. Furthermore, the NIR solar reflectance of the superhydrophobic montmorillonite/SiO 2 composite coatings ranged from 0.77 to 0.85. The composite coatings reduced the heat box’s inside temperature of by 5.9℃. Therefore, the integration of high NIR reflectance property and superior self-cleaning property makes montmorillonite/SiO 2 composite coatings good candidates as self-cleaning cool roof coatings for energy-saving buildings.
研究领域:
材料科学
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能源与环境工程
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产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2017
·Vol. 52
·期 20
·12358-12369
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IF 2.599
Ji Shengning,Zhang Zhiming,Jiang Xiaohui,Yu Liangmin
The three-layer core–shell–shell γ-Fe 2 O 3 –SiO 2 –poly (3,4-ethylenedioxythiophene) (PEDOT) nanocomposite has been successfully synthesized by a facile chemical process followed by a detailed investigation of morphology, composition, electromagnetic, and microwave absorption properties. The electrical conductivity of γ-Fe 2 O 3 –SiO 2 –PEDOT nanocomposites was as high as 3.34 S cm −1 , and the saturation magnetization was in the range of 1–7 emu g −1 . The minimum reflection loss reached −27.5 dB at 13.8 GHz with a matching layer thickness of 2.0 mm and an effective absorption bandwidth (< −10 dB) of about 4.1 GHz (12.0–16.1 GHz). The excellent microwave absorbing performance of this nanocomposite is due to proper impedance matching and the synergistic interaction of dielectric loss, the magnetic loss, and core–shell microstructure. Moreover, the electromagnetic and microwave absorbing properties of γ-Fe 2 O 3 –SiO 2 –PEDOT nanocomposites can be regulated by changing the dosage of functionalized γ-Fe 2 O 3 –SiO 2 .
研究领域:
材料科学
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电磁学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Jie Zhu,Sifan Wang,Jiaji Zhang,Zhecheng Fang,Weitao Ji,Gaobo Lin,Lei Guo,Bolong Li,Jianghao Wang,Jie Fu
Constructing a stable Cu 0 /Cu 2+ interface is critical for enhancing the C-C coupling during the process of CO 2 electroreduction. However, the high-valence Cu species are unstable under the operating conditions. Herein, polyhedral-shaped CuO is coated with hydroxy-rich SiO 2 nanoparticles (m-SiO 2 /CuO) to stabilize the Cu 2+ species, enabling efficient CO 2 reduction to the ethylene product. Significantly, the optimal m-SiO 2 /CuO catalyst exhibits an impressive Faradaic efficiency of 55.5 % and an industrial-level partial current density of 500 mA cm −2 toward ethylene. Fourier transform infrared spectra and X-ray photoelectron spectra reveal that the strong interfacial interaction between CuO and hydroxy-rich SiO 2 is conducive to stabilizing the Cu 2+ species. In-situ characterizations reveal that the Cu 0 /Cu 2+ interface facilitates CO 2 activation and the key intermediate *OCCHO, thus promoting the production of ethylene. This work paves the way for developing advanced electro-catalysts of producing ethylene.
研究领域:
材料科学
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电化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of the Taiwan Institute of Chemical Engineers
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2019
·
IF 3.834
Wenjing Cheng,Yun Li,Xiaoying Li,Wenjing Bai,Yunxiao Liang
A monolithic macroporous silica (MMS) was prepared by using a pillared epoxy resin macroporous polymer as template. Polydopamine (PDA) as a spacer-arm polymer was modified on the surface of MMS for immobilization of Candida rugosa lipase (CRL), aiming to improve the performance of CRL and overcome the limitations of the immobilized enzymes on mesoporous materials and fine particles. The immobilization conditions and the properties of the immobilized CRL were investigated. The as-prepared monolithic macroporous materials were characterized by SEM, TEM, MIP, BET, FT-IR and TG-DTA. The results revealed that MMS possessed two sets of well-defined and uniform continuous macroporous channels (pore size of 300–500 nm), high mechanical strength, large pore volume and specific surface area, and that the PDA/MMS macroporous composite was constructed by PDA/SiO 2 /PDA nano-film with a thickness of about 50 nm. Because of its surface chemical properties and unique macropore structure, the PDA/MMS composite provided a simple, cost-effective way to enhance the catalytic activity of directly immobilized enzyme. The activity recovery of CRL–PDA/MMS was 201%, and the stability of the immobilized lipase was remarkably improved. Moreover, this biocatalyst can be easily recovered from the reaction system without centrifugation or filtration.
研究领域:
生物化学
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材料科学
·
酶工程
✓ 已验证
DOI
高影响因子
JOURNAL OF POLYMER RESEARCH
·
2023
·Vol. 30
·期 10
·1-13
·
IF 2.8
Li Heng,Chen Limiao,Li Zhongbei,Wang Wengui,Liu Ying,Huang Xuemei,Liu Yaochi
The combination of nitrogen and phosphorus compounds has synergistic flame retardant effect, but the addition of low phosphorus content compounds is large, which affects the mechanical properties of polymers. Phosphorus ammonium polyphosphate (APP) with high phosphorus content and graphitic carbon nitride (g-C 3 N 4 ) doped with SiO 2 were used for the flame retardant (CN-Si-APP) of polyamide 6 (PA6). CN-Si-APPs with different APP/CN mass ratio (1, 2.5 and 4) and dosage (7 and 12 wt%) were blended with PA6 via a twin-screw extruder, and their flame retardancy was investigated by limiting oxygen index (LOI), UL-94 test, muffle furnace carbonization test and raman spectroscopy. When only APP added, the coefficient of water absorption (CWA) of composites increased and its tensile strength greatly reduced by nearly 37.1% to 35.39 MPa. The addition of g-C 3 N 4 inhibited the water absorption. When the addition dosage is 7%, the CWA of PA6/APP, PA6/CN-Si-APP2.5, PA6 and PA6/CN were 11.1, 6.86, 5.78 and 4.6%, respectively. SiO 2 effectively improved the dispersion of g-C 3 N 4 and the mechanical properties of composites. Thermogravimetric analysis (TGA) showed that the char residue of PA6 composites was improved significantly. The composite with 7 wt% CN-Si-APP4 passed the UL-94 V-0 rating. The LOI value and graphitization degree (I D /I G ) of PA6/12 wt% CN-Si-APP2.5 reached 28.7% and 2.93 respectively. Under the same dosage, the graphitization degree of CN-Si-APP2.5 (3.51) was higher than that of g-C 3 N 4 (3.98). The barrier protection of g-C 3 N 4 , catalytic effect of APP and SiO 2 crosslinking network promoted PA6 to form a dense and stable char layer, which protected PA6 composites from the flame. The strategy of synergistic flame retardant in this paper provides a valuable solution for reducing the amount of flame retardant.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
Journal of Nanomaterials
·
2013
·
IF 1.547
Yaohui Xu,Yang Zhou,Wenhui Ma,Shixing Wang
The magnetic Fe3O4@SiO2 nanoparticles (NPs) functionalized with 8-chloroacetylaminoquinoline as a fluorescent sensor for detection and removal of Zn2+ have been synthesized. The core-shell structures of the nanoparticles and chemical composition have been confirmed by TEM, XRD, FTIR, and XPS techniques. The addition of functionalized Fe3O4@SiO2 NPs into the acetonitrile solution of Zn2+ had an effect of visual color change as well as significant fluorescent enhancement. High-saturated magnetizations (24.7 emu/g) of functionalized Fe3O4@SiO2 NPs could help to separate the metal ions from the aqueous solution. The magnetic sensor exhibited high removal efficiency towards Zn2+ (92.37%). In this work, we provided an easy and efficient route to detect Zn2+ and simultaneously remove Zn2+.
研究领域:
材料科学
·
环境科学
·
分析化学
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2019
·
IF 4.63
Shenxiao Li,Yong Men,Jinguo Wang,Shuang Liu,Xuefei Wang,Fei Ji,Shanshan Chai,Qiaoling Song
In this work, three novel MgO-SiO 2 composite catalysts with inverted structure have been synthesized via a facile and scalable strategy by means of the incipient wetness impregnation of the silica sol onto MgO precursors with different morphologies, and evaluated for the one-step conversion of ethanol to 1,3-butadiene. The prepared flower-like MgO-SiO 2 composite catalysts exhibited highly enhanced catalytic activity than those catalysts synthesized from MgO precursors with nanodisks and nanosheets morphologies. Characterization results based on XRD, FT-IR, UV–vis, BET, CO 2 -TPD, NH 3 -TPD, ethanol-TPD, and 29 Si MAS NMR revealed that unique layered flower-like architectures may facilitate the formation of interfacial Mg-O-Si chemical bond in binary MgO-SiO 2 composite catalysts which are mainly responsible for the superior activity. This study presents a new strategy to design and develop the catalyst for efficient conversion of bio-ethanol to 1,3-butadiene by morphological control of MgO-SiO 2 bifunctional catalysts.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2016
·
IF 2.567
Bing Xue,Lei Hui,Huaqin Yang,Yulai Zhao,Linxi Hou,Wei Li
A macroporous SiO2 (Macro-SiO2), which has uniformed macropores, an open-framework structure, and thin walls, was synthesized to support Ziegler–Natta catalysts. The immobilization behaviors of the Ziegler–Natta catalysts inside the Macro-SiO2 were investigated. Notable agglomerations of δ-MgCl2/titanium complex were observed because of the unconstrained environment of the Macro-SiO2. A highly superficial Ti content and a heterogeneously chemical structure of Ti active sites were thus achieved inside the Macro-SiO2. The ethylene polymerization results revealed that the Macro-SiO2/MgCl2/TiCl4 exhibited much higher catalytic activity (i.e., 12.1 × 106 g PE·(mol Ti·h)−1 or 17.8 × kg PE·(g cat·h)−1) than that of the traditional 955-SiO2 supported catalyst (i.e., 2.0 × 106 g PE·(mol Ti·h)−1 or 2.7 × kg PE·(g cat·h)−1). Finally, the fragmentation behavior of Macro-SiO2/MgCl2/TiCl4 was investigated during the polymerization. This unconstrained environment of Macro-SiO2 afforded fewer resistances to the diffusion of reactants and also the polymer growth.
研究领域:
材料科学
·
化学工程
·
高分子科学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS LETTERS
·
2021
·Vol. 151
·期 7
·2144-2152
·
IF 3.186
Guo Yu,Tian Long,Yan Wangwei,Qi Ronghua,Tu Weixia,Wang Zhou-jun
Abstract Three typical methods, subsequent coating, co-impregnation and sequential impregnation, were employed to investigate the effect of introduction methodologies for CeO 2 -promoted Ni/SiO 2 catalysts. The CeO 2 @Ni/SiO 2 catalyst prepared with the subsequent coating method was found to exhibit the best initial activity and superior long-term stability in CO 2 reforming of methane. Comparative characterizations documented that small Ni size and intimate Ni–CeO 2 contact were generated on the CeO 2 @Ni/SiO 2 catalyst, leading to excellent reforming activity. In addition, pronounced redox property and strong surface basicity were created on the CeO 2 @Ni/SiO 2 catalyst, resulting in exceptional coke resistance and thus superior long-term stability. This work unravels the impact of various introduction methods on the catalyst structure, which would help design robust nanocomposite catalysts with outstanding catalytic performance. Graphic Abstract
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
危险品化学品经营许可证（带存储）