JOURNAL OF ALLOYS AND COMPOUNDS
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2023
·
IF 6.2
Wenchao Zhang,Liangjun Wang,Shiyu Liu,Feng Guan,Min Jiang,Yanpeng Li,Dong Yue,Jialong Li,Xiaoxu Liu,Yu Feng
It is important that the dielectric material in the electrical system be able to handle the increasing applied electric strength owing to the rising demands for power supply reliability. Based on this, in this work, Nb 2 O 5 donor doped SiO 2 (NSO) particles were synthesized by high-temperature sintering method and successfully doped into the PI matrix. The maximum E b of the composite material is 527.3 kV/mm, which is 64.2% higher than that of pure PI (321.1 kV/mm) and 34.8% higher than that of the SiO 2 /PI composite material (392.5 kV/mm) owning to the effect of donor doping on the carrier transport of the composite material. At the same time, it maintains excellent dielectric stability and lower dielectric loss even at 100 ℃. These consequences offer a new strategy for enhancing the integrated dielectric properties of polymer dielectrics in insulation fields.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2023
·
IF 9.9
Jiang Wu,Kanghui Ke,Ni Qin,Enzhu Lin,Zihan Kang,Dinghua Bao
The piezo-/photocatalytic effects of ZnO have been in the limelight because of their great potential in environmental remediation and energy conversion. However, the poor recyclability of the suspended catalysts can cause inevitable secondary pollution, which is one of the major issues that limit the practical application of these materials. To address this problem, a magnetically retrievable Fe 3 O 4 @SiO 2 @ZnO nanocomposite was designed and successfully synthesized by multi-step reactions. The ZnO nanorods were vertically grown on the surface of the magnetic Fe 3 O 4 @SiO 2 microspheres , while SiO 2 served as an insulator to protect the inner core and to inhibit charge transfer across the core/shell interface. The Fe 3 O 4 @SiO 2 @ZnO nanocomposite can be easily collected and separated by using a magnetic field. Along with the good recyclability, the material also exhibited high efficiencies in piezocatalytic, photocatalytic and piezo-photocatalytic dye degradation processes. The rate constant of piezo-photocatalysis reached 95.9 × 10 −3 min −1 , which was 2.2 and 6.1 times that of the individual piezocatalysis and photocatalysis , respectively. The present result confirmed the existence of a synergetic effect between piezo- and photocatalytic processes. Hereby, we demonstrated that incorporation of a magnetic carrier is a feasible strategy to achieve retrievable and highly efficient piezo-/photocatalyst.
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INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
·
2022
·Vol. 24
·期 1
·504
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IF 6.208
Zhilan Du,Dashuang Wang,Xinfang Zhang,Zhiyu Yi,Jihai Tang,Pingan Yang,Rui Cai,Shuang Yi,Jinsong Rao,Yuxin Zhang
In this work, a novel core-shell structure material, NiFe layered double hydroxide (NiFe LDH) loaded on SiO2microspheres (SiO2@NiFe LDH), was synthesized by a one-step hydrothermal method, and the spontaneous electrostatic self-assembly process. The morphology, structure, and microwave absorption properties of SiO2@NiFe LDH nanocomposites with different NiFe element ratios were systematically investigated. The results show that the sample of SiO2@NiFe LDH-3 nanocomposite has excellent microwave absorption properties. It exhibits broadband effective absorption bandwidth (RL < −10 dB) of 8.24 GHz (from 9.76 GHz to 18.0 GHz) and the reflection loss is −53.78 dB at the matched thickness of 6.95 mm. It is expected that this SiO2@NiFe-LDH core-shell structural material can be used as a promising non-precious, metal-based material microwave absorber to eliminate electromagnetic wave contamination.Keywords:SiO2microspheres;LDH;microwave absorption;core-shell structure
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2022
·
IF 24.319
Haolan Liu,Zhili Chang,Jie Fu,Zhaoyin Hou
Cu-based catalysts play pivotal role in many industrial processes, however, its application under high temperature is restricted due to the low Tammann temperature of Cu. Improving the stability and activity of Cu-based catalysts at high temperature is a challenge. In this work, a stable Cu/ZnO@SiO 2 catalyst was prepared, in which silicon was introduced into CuZn-BTC precursor via a steam-assisted hydrolysis method before calcination and reduction. Characterizations found that Cu/ZnO@SiO 2 catalyst prepared via above strategy possesses increased surface area, more exposed active sites and excellent stability for ethanol dehydrogenation than Cu/ZnO (prepared from CuZn-BTC without SiO 2 ). It was confirmed that the space-time yield of acetaldehyde reached 9.0 g-acetaldehyde/g-cat/h, and Cu/ZnO@SiO 2 could maintain its activity within 200 h at 350 °C due to the ZnO decorated Cu particles (Cu/ZnO) were encapsulated in the octahedral shaped SiO 2 hollow.
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Frontiers in Chemistry
·
2022
·
IF 5.545
Sun Xun,Chen Mingming,Lei Jiayu,Liu Xinran,Ke Xin,Liu Wengang,Wang Jingkuan,Gao Xiaodan,Liu Xin,Zhang Yun
In this study, β-CD@mesoporous SiO2 nanospheres (β-CD@mSi) were prepared by loading β-cyclodextrin (β-CD) onto mesoporous silica nanospheres through an in situ synthesis. This not only solved the defect of β-CD being easily soluble in water, but also changed the physical structure of the mesoporous silica nanospheres. FTIR and XPS results showed that β-CD was successfully loaded onto mesoporous silica nanospheres (mSi), while enhancing the adsorption effect. β-CD@mSi with a monomer diameter of about 150 nm were prepared. At a temperature of 298k, the removal efficiency of a 100 mg/L solution of rifampicin can reach 90% in 4 h and the adsorption capacity was 275.42 mg g−1 at high concentration. Through the calculation and analysis of adsorption kinetics, adsorption isotherms and adsorption thermodynamics based on the experimental data, the reaction is a spontaneous endothermic reaction dominated by chemical adsorption. The electron transfer pathway, structure–activity relationship and energy between β-CD@mSi and rifampicin were investigated by quantum chemical calculations. The accuracy of the characterization test results to judge the adsorption mechanism was verified, to show the process of rifampicin removal by β-CD@mSi more clearly and convincingly. The simulation results show that π–π interaction plays a major interaction in the reaction process, followed by intermolecular hydrogen bonding and electrostatic interactions.
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CATALYSIS LETTERS
·
2022
·Vol. 153
·期 9
·2787-2802
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IF 2.936
Shi Yu,Li Yiming,Wang Shiwei,Chu Yuting,Yu Hongbo,Li Tong,Yin Hongfeng
A series of relative inert SiO 2 supported NiP-x/SiO 2 catalysts, containing different ratio of metallic nickel to nickel phosphides, were employed to clarify the synergistic effect of metallic nickel–nickel phosphides in dry methane reforming reaction. Ni/SiO 2 catalyst exhibits good activity but severe carbon deposition and visible nickel particles sintering in dry methane reforming, which results in evident deactivation after 50 h reaction. The presence of P increases the dispersion of nickel species, results in smaller nickel species particles size. The co-existence of metallic nickel and nickel phosphides species was confirmed by multiple characterizations. Because of the relative stronger CO 2 dissociation properties, NiP-x/SiO 2 catalysts exhibit higher resistance of carbon deposition. In addition, P content makes great difference to not only carbon deposition but also activity in dry methane reforming. NiP-3/SiO 2 , which has good activity, stability and anti-coking properties in dry methane reforming, is the optimal catalyst in our study scope. Graphical Abstract
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ChemistrySelect
·
2022
·Vol. 7
·期 47
·e202200923
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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.
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Journal of Materials Chemistry A
·
2022
·Vol. 10
·期 7
·3400-3408
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IF 14.511
Cheng Wang,Tianqi Yang,Wenkui Zhang,Hui Huang,Yongping Gan,Yang Xia,Xinping He,Jun Zhang
The use of solid electrolytes can fundamentally change energy storage systems due to their higher safety and energy density. Herein, we design hydrogen-bonded polyethylene oxide (PEO) composite solid electrolytes (CSEs), which are hydrolyzed by tetraethyl orthosilicate (TEOS) in alkaline solution to form SiO2 with rich hydroxyl groups on its surface. This in situ formed SiO2 can not only reduce the crystallinity of PEO and increase the ionic conductivity (1.8 × 10−4 S cm−1 at 30 °C), but also adsorb anions so as to increase the lithium-ion transference number (tLi+ = 0.42). More importantly, hydrogen bonding can be formed with PEO, LITFSI and succinonitrile to form an interconnected network to improve the mechanical strength (Young's modulus = 0.72 GPa). In addition, we avoid the poor film formability and low mechanical strength by adjusting the ratio of EO : Li to 30 : 1 to reduce the content of lithium salt in the CSEs. Due to the high mechanical strength, the critical current density of lithium symmetrical batteries is as high as 1.4 mA cm−2. Using this CSE, a solid state LiFePO4‖Li battery delivers a high discharge capacity of 161.2 mA h g−1 at 0.5C with a capacity retention of 88% after 400 cycles at 30 °C. The in situ formed highly dispersed SiO2 reinforced PEO with abundant hydrogen bonds enables high performance of solid-state lithium batteries at room temperature.
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REACTIVE & FUNCTIONAL POLYMERS
·
2022
·
IF 4.966
Beiping Dong,Ziang Li,Juncheng Liu,Lifang Nie
Coating antireflection film on the surface of glass cover is one of the important methods to improve the photoelectric conversion efficiency of solar cells. Sol-gel method is suitable for low cost and large area preparation of antireflection film. However, most of antireflective films prepared with sol-gel have not enough good mechanical properties , and their applications are restricted. A porous antireflection film was prepared with sol-gel, where the polyethylene glycol monomethyl ether (mPEG) was used as the porogen . The effects of the mPEG additive amount were investigated on the microstructure and properties of the film. The results showed that the transmittance of the film (the coated glass) first increases and then decreases with the increase of the amount of mPEG. When the amount of mPEG is 0.6 g, the average transmittance of the film in the wavelength range of 380–1100 nm is the highest, higher than that of glass substrate by 4.2 percentage points. The adhesion of the film reaches grade 0 and the hardness is greater than 9H. The efficiency of monocrystalline silicon solar cells could be increased from 11.65% to 12.04%, by a relative increase of 3.35%
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Gels
·
2022
·Vol. 8
·期 5
·286
·
IF 4.432
Fei Gao,Xinyu Zhao,Jinglin Liu
Europium trivalent ion (Eu3+)-doped silica nanowires were prepared, and the positioning of Eu3+in the silicon dioxide nanowire matrix was researched. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction analysis (XRD) and energy-dispersive X-ray spectroscope analysis (EDX) were used to characterize the product’s morphology and structure. The representation of Fourier transform infrared spectra (FT-IR) and X-ray photoelectron spectroscopy (XPS) were indicative of the presence of a covalent Eu-O-Si bond. The results suggest that Eu3+was successfully doped into amorphous silica. Furthermore, a sol-gel inorganic−organic co-assembly mechanism model was proposed to illuminate the formation of the rare-earth ion-doped nanowires. In addition, photoluminescent emission of europium ions in a silica matrix was further discussed. It was demonstrated that a 10% content of Eu3+resulted in a quenching effect and after annealing at 650 °C, the europium ions in the nanowires had a high luminescence intensity due to the silica network structure.Keywords:tartaric acid;europium;silica nanowires;sol–gel;photoluminescence
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CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Xuan Wang,Hao Ding,Guocheng Lv,Run Zhou,Ruixin Ma,Xifeng Hou,Jianmeng Zhang,Wei Li
Generally, superhydrophilic self-cleaning coatings are prepared from semiconductors with photocatalytic properties. Organic pollutants attached to the coating surface can be degraded by its photocatalytic performance realizing a self-cleaning goal. Herein, SiO 2 –TiO 2 composite particles were fabricated by the hydrolysis and precipitation of TiOSO 4 , and SiO 2 microspheres were chosen as carriers, which are inexpensive and environmentally friendly. Then, superhydrophilic self-cleaning SiO 2 –TiO 2 coatings were fabricated by spraying the composites on the surfaces of substrates. The morphology, structure and self-cleaning performance of the SiO 2 –TiO 2 coating were characterized and tested. The results revealed that nano-TiO 2 was loaded on the surfaces of SiO 2 microspheres uniformly forming a hierarchical micro/nanostructure. The SiO 2 –TiO 2 composite particles exhibited excellent photocatalytic degradation performance, and the degradation rate of methyl orange (10 ppm) was more than 98% under UV irradiation for 40 min. Furthermore, the coating prepared with the SiO 2 –TiO 2 composite particles exhibited superhydrophilicity. A water droplet spreads completely on the coating surface in 0.35 s, and the contact angle reaches 0°. In addition, rhodamine B (RhB) and methylene blue (MB) on the coating surface can be degraded efficiently under sunlight irradiation. The SiO 2 –TiO 2 composite particles can be sprayed directly on the surfaces of concrete, brick, wood, and glass slides. Therefore, the particles showed good adaptability to different substrates. The superhydrophilic property was due to the hydrophilicity of SiO 2 and TiO 2 , the hierarchical micro/nanostructure of the SiO 2 –TiO 2 composites, and the photoinduced superhydrophilicity of TiO 2 . The above experimental results show that the as-prepared superhydrophilic self-cleaning SiO 2 –TiO 2 coating has a large application potential.
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DENTAL MATERIALS
·
2022
·
IF 5.687
Jing Cao,Dan-Lei Yang,Dan Wang,Jie-Xin Wang
Objective The objective of this study is to develop novel CaF 2 /SiO 2 nanoclusters (NCs) fillers, which can endow the dental resin composites (DRCs) with excellent mechanical properties , stable and sustained fluoride ion release, and good antibacterial activity . Methods The CaF 2 /SiO 2 NCs were efficiently fabricated by assembling CaF 2 /SiO 2 nanoparticles (NPs) as building blocks with a spray-drying technology. CaF 2 /SiO 2 NCs with different SiO 2 coating amounts (20 wt%, 50 wt% and 80 wt%) were incorporated into the DRCs at the filler content of 55 wt% for the measurement of mechanical properties including flexural strength , flexural modulus, compressive strength , and hardness. The effect of the filling amount of CaF 2 /50SiO 2 NCs (50 represents 50 wt% SiO 2 coating amount) in the DRCs was investigated, while CaF 2 /50SiO 2 NPs were adopted as comparison group. The fluoride ion release and antibacterial activity of the DRCs with the optimal mechanical performances were evaluated. Furthermore, the statistical analyses were performed for mechanical properties. Results Spherical CaF 2 /50SiO 2 NCs with an average size of 2.4 µm were obtained at the feed rate of 7.4 mL/min and the CaF 2 /50SiO 2 NPs solid content of 2 wt% in the suspension. The optimum comprehensive performances of the DRCs can be achieved by filling 55 wt% CaF 2 /50SiO 2 NCs. Compared with CaF 2 /50SiO 2 NPs, the filling amount of CaF 2 /50SiO 2 NCs was increased by 5 wt% (50–55 wt%), and under the same filling amount of 50 wt%, the flexural strength, flexural modulus, compressive strength, and hardness of the DRCs containing CaF 2 /50SiO 2 NCs were improved by 9.8%, 17.7%, 7.5% and 69.8%, respectively. Furthermore, the DRCs filled with 50 wt% CaF 2 /50SiO 2 NCs exhibited more cumulative F-release by 126% and more stable F-release rate than the counterpart filled with 50 wt% CaF 2 /50SiO 2 NPs after immersed for 1800 h. And 55 wt% CaF 2 /50SiO 2 NCs filled DRCs could inhibit the growth of S. mutans, reaching an antibacterial ratio of 93%. Significance The spray-dried CaF 2 /50SiO 2 NCs are promising fillers for the development of high-performance multifunctional DRCs.
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