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Influences of spinel type and polymeric surfactants on the size evolution of colloidal magnetic nanocrystals (MFe

Tahereh R. BASTAMI,Mohammad H. ENTEZARI,Chiwai KWONG,Shizhang QIAO

《化学科学与工程前沿(英文)》 2014年 第8卷 第3期   页码 378-385 doi: 10.1007/s11705-014-1441-y

摘要: Two types of polymeric surfactants, PEG and PVP , were used for the preparation of magnetic ferrite MFe O (M= Mn, Fe) colloidal nanocrystals using a solvothermal reaction method. The effect of spinel type effect on the size evolution of various nanoparticles was investigated. It was found that Fe O nanoparticles exhibited higher crystalinity and size evolution than MnFe O nanoparticles with use of the two surfactants. It is proposed that this observation is due to fewer tendencies of surfactants on the surface of Fe O building blocks nanoparticles than MnFe O . Less amounts of surfactant or capping agent on the surface of nanoparticles lead to the higher crystalibity and larger size. It is also suggested that the type of spinel (normal or inverted spinel) plays a key role on the affinity of the polymeric surfactant on the surface of building blocks.

关键词: spinel type     polymeric surfactant     size evolution     mangnetic ferrite nanoparticle    

Activated carbon induced oxygen vacancies-engineered nickel ferrite with enhanced conductivity for supercapacitor

《化学科学与工程前沿(英文)》 2023年 第17卷 第12期   页码 2088-2100 doi: 10.1007/s11705-023-2352-6

摘要: Activated carbon induced oxygen vacancies-engineered nickel ferrite with enhanced conductivity for supercapacitor application

关键词: nickel ferrite conductivity     carbon oxygen vacancies    

A novel algorithm for frequency dependent modeling of ferrite ring and its optimum design to study VFTO

Mehrdad MAJIDI, Hamid JAVADI, Moein MANBACHI

《能源前沿(英文)》 2014年 第8卷 第1期   页码 90-100 doi: 10.1007/s11708-013-0286-2

摘要: One of the fundamental issues in gas insulated substations (GIS) which has destructive effects on GIS equipment is the very fast transient over-voltages (VFTOs). This paper models a 400/230 kV substation in order to study the effects of VFTO extensively implemented on EMTP-RV. In addition, the application of ferrite rings for suppressing VFTOs is assessed thoroughly. The main advantage of this paper is its new proposed algorithm according to the ferrite ring frequency dependent modeling that is validated with experimental results. This paper examines the effects of three compositions of the ferrite ring on VFTO suppression. Moreover, it estimates the dimension of the ferrite ring based on the SF6 gas insulation withstand and the maximum effect of ferrite rings on VFTO suppression constraint with the COMSOL multiphysics software. Furthermore, it gains VFTO attenuated percentages due to the installation of the ferrite ring in different GIS nodes. Finally, it analyzes the offered VFTO amendment technique in various GIS switching scenarios.

关键词: comsol multiphysics     EMTP-RV     ferrite ring     gas insulated substations (GIS)     transient over-voltage     insulation coordination    

Performance of iron-air battery with iron nanoparticle-encapsulated C–N composite electrode

《能源前沿(英文)》 doi: 10.1007/s11708-023-0913-5

摘要: Highly efficient and stable iron electrodes are of great significant to the development of iron-air battery (IAB). In this paper, iron nanoparticle-encapsulated C–N composite (NanoFe@CN) was synthesized by pyrolysis using polyaniline as the C–N source. Electrochemical performance of the NanoFe@CN in different electrolytes (alkaline, neutral, and quasi-neutral) was investigated via cyclic voltammetry (CV). The IAB was assembled with NanoFe@CN as the anode and IrO2 + Pt/C as the cathode. The effects of different discharging/charging current densities and electrolytes on the battery performance were also studied. Neutral K2SO4 electrolyte can effectively suppress the passivation of iron electrode, and the battery showed a good cycling stability during 180 charging/discharging cycles. Compared to the pure nano-iron (NanoFe) battery, the NanoFe@CN battery has a more stable cycling stability either in KOH or NH4Cl + KCl electrolyte.

关键词: energy storage and conversion     metallic composites     nanocomposites     iron-air battery     iron anode    

Effect of noble metal nanoparticle size on C–N bond cleavage performance in hydrodenitrogenation: a study

《化学科学与工程前沿(英文)》 2023年 第17卷 第12期   页码 1986-2000 doi: 10.1007/s11705-023-2337-5

摘要: Breakage of the C–N bond is a structure sensitive process, and the catalyst size significantly affects its activity. On the active metal nanoparticle scale, the role of catalyst size in C–N bond cleavage has not been clearly elucidated. So, Ru catalysts with variable nanoparticle sizes were obtained by modulating the reduction temperature, and the catalytic activity was evaluated using 1,2,3,4-tetrahydroquinoline and o-propylaniline with different C–N bond hybridization patterns as reactants. Results showed a 13 times higher reaction rate for sp3-hybridized C–N bond cleavage than sp2-hybridized C–N bond cleavage, while the reaction rate tended to increase first and then decrease as the catalyst nanoparticle size increased. Different concentrations of terrace, step, and corner sites were found in different sizes of Ru nanoparticles. The relationship between catalytic site variation and C–N bond cleavage activity was further investigated by calculating the turnover frequency values for each site. This analysis indicates that the variation of different sites on the catalyst is the intrinsic factor of the size dependence of C–N bond cleavage activity, and the step atoms are the active sites for the C–N bond cleavage. When Ru nanoparticles are smaller than 1.9 nm, they have a strong adsorption effect on the reactants, which will affect the catalytic performance of the Ru catalyst. Furthermore, these findings were also confirmed on other metallic Pd/Pt catalysts. The role of step sites in C–N bond cleavage was proposed using the density function theory calculations. The reactants have stronger adsorption energies on the step atoms, and step atoms have d-band center nearer to the Fermi level. In this case, the interaction with the reactant is stronger, which is beneficial for activating the C–N bond of the reactant.

关键词: sp3/sp2-hybridized C–N bond     noble metal nanoparticle     catalytic active site     turnover frequency     DFT    

Iron oxide nanoparticle-based theranostics for cancer imaging and therapy

Xiaoqing REN,Hongwei CHEN,Victor YANG,Duxin SUN

《化学科学与工程前沿(英文)》 2014年 第8卷 第3期   页码 253-264 doi: 10.1007/s11705-014-1425-y

摘要: Theranostic platform, which is equipped with both diagnostic and therapeutic functions, is a promising approach in cancer treatment. From various nanotheranostics studied, iron oxide nanoparticles have advantages since IONPs have good biocompatibility and spatial imaging capability. This review is focused on the IONP-based nanotheranostics for cancer imaging and treatment. The most recent progress for applications of IONP nanotheranostics is summarized, which includes IONP-based diagnosis, magnetic resonance imaging (MRI), multimodal imaging, chemotherapy, hyperthermal therapy, photodynamic therapy, and gene delivery. Future perspectives and challenges are also outlined for the potential development of IONP based theranostics in clinical use.

关键词: theranostics     iron oxide nanoparticles     MRI     drug delivery     photothermal therapy     photodynamic therapy    

Nanoparticle-enhanced coolants in machining: mechanism, application, and prospects

《机械工程前沿(英文)》 2023年 第18卷 第4期 doi: 10.1007/s11465-023-0769-8

摘要: Nanoparticle-enhanced coolants (NPECs) are increasingly used in minimum quantity lubrication (MQL) machining as a green lubricant to replace conventional cutting fluids to meet the urgent need for carbon emissions and achieve sustainable manufacturing. However, the thermophysical properties of NPEC during processing remain unclear, making it difficult to provide precise guidance and selection principles for industrial applications. Therefore, this paper reviews the action mechanism, processing properties, and future development directions of NPEC. First, the laws of influence of nano-enhanced phases and base fluids on the processing performance are revealed, and the dispersion stabilization mechanism of NPEC in the preparation process is elaborated. Then, the unique molecular structure and physical properties of NPECs are combined to elucidate their unique mechanisms of heat transfer, penetration, and anti-friction effects. Furthermore, the effect of NPECs is investigated on the basis of their excellent lubricating and cooling properties by comprehensively and quantitatively evaluating the material removal characteristics during machining in turning, milling, and grinding applications. Results showed that turning of Ti‒6Al‒4V with multi-walled carbon nanotube NPECs with a volume fraction of 0.2% resulted in a 34% reduction in tool wear, an average decrease in cutting force of 28%, and a 7% decrease in surface roughness Ra, compared with the conventional flood process. Finally, research gaps and future directions for further applications of NPECs in the industry are presented.

关键词: nanoparticle-enhanced coolant     minimum quantity lubrication     biolubricant     thermophysical properties     turning     milling     grinding    

Cobalt nanoparticle decorated N-doped carbons derived from a cobalt covalent organic framework for oxygen

《化学科学与工程前沿(英文)》 2021年 第15卷 第6期   页码 1550-1560 doi: 10.1007/s11705-021-2104-4

摘要: The low cost and highly efficient construction of electrocatalysts has attracted significant attention owing to the use of clean and sustainable energy technologies. In this work, cobalt nanoparticle decorated N-doped carbons (Co@NC) are synthesized by the pyrolysis of a cobalt covalent organic framework under an inert atmosphere. The Co@NC demonstrates improved electrocatalytic capabilities compared to N-doped carbon without the addition of Co nanoparticles, indicating the important role of cobalt. The well-dispersed active sites (Co-Nx) and the synergistic effect between the carbon matrix and Co nanoparticles greatly enhance the electrocatalytic activity for the oxygen reduction reaction. In addition, the Co content has a significant effect on the catalytic activity. The resulting Co@NC-0.86 exhibits a superb electrocatalytic activity for the oxygen reduction reaction in an alkaline electrolyte in terms of the onset potential (0.90 V), half-wave potential (0.80 V) and the limiting current density (4.84 mA·cm–2), and a high selectivity, as well as a strong methanol tolerance and superior durability, these results are comparable to those of the Pt/C catalyst. Furthermore, the superior bifunctional activity of Co@NC-0.86 was also confirmed in a home-built Zn-air battery, signifying the possibility for application in electrode materials and in current energy conversion and storage devices.

关键词: cobalt embedment     N-doped carbons     covalent organic framework     oxygen reduction     Zn-air battery    

Cobalt-nanoparticle catalysts derived from zeolitic imidazolate framework@MXene composites for efficient

《化学科学与工程前沿(英文)》 2023年 第18卷 第1期 doi: 10.1007/s11705-023-2378-9

摘要: In this study, we synthesize a catalyst comprising cobalt nanoparticles supported on MXene by pyrolyzing a composite in a N2 environment. Specifically, the composite comprises a bimetallic Zn/Co zeolitic imidazole framework grown in situ on the outer surface of MXene. The catalytic efficiency of the catalyst is tested for the self-coupling of 4-methoxybenzylamine to produce value-added imine, where atmospheric oxygen (1 atm) is used as the oxidant. Based on the results, the catalyst displayed impressive catalytic activity, achieving 95.4% yield of the desired imine at 383 K for 8 h. Furthermore, the catalyst showed recyclability and tolerance toward benzylamine substrates with various functional groups. The outstanding performance of the catalyst is primarily attributed to the synergetic catalytic effect between the cobalt nanoparticles and MXene support, while also benefiting from the three-dimensional porous structure. Additionally, a preliminary investigation of potential reaction mechanisms is conducted.

关键词: MXene     sacrificial template     oxidative self-coupling     Co nanoparticles     imine    

A mini-review of ferrites-based photocatalyst on application of hydrogen production

《能源前沿(英文)》 2021年 第15卷 第3期   页码 621-630 doi: 10.1007/s11708-021-0761-0

摘要: Photocatalytic water splitting for hydrogen production is a promising strategy to produce renewable energy and decrease production cost. Spinel-ferrites are potential photocatalysts in photocatalytic reaction system due to their room temperature magnetization, the high thermal and chemical stability, narrow bandgap with broader visible light absorption, and proper conduction band energy level with strong oxidation activity for water or organic compounds. However, the fast recombination of the photoexcited electrons and holes is a critical drawback of ferrites. Therefore, the features of crystallinity, particle size, specific surface area, morphology, and band energy structure have been summarized and investigated to solve this issue. Moreover, composites construction with ferrites and the popular support of TiO2 or g-C3N4 are also summarized to illustrate the advanced improvement in photocatalytic hydrogen production. It has been shown that ferrites could induce the formation of metal ions impurity energy levels in TiO2, and the strong oxidation activity of ferrites could accelerate the oxidation reaction kinetics in both TiO2/ferrites and g-C3N4/ferrites systems. Furthermore, two representative reports of CaFe2O4/MgFe2O4 composite and ZnFe2O4/CdS composite are used to show the efficient heterojunction in a ferrite/ferrite composite and the ability of resistance to photo-corrosion, respectively.

关键词: photocatalyst     spinel-ferrite     composite     photocatalytic hydrogen production    

A review on the application of nanofluids in enhanced oil recovery

《化学科学与工程前沿(英文)》 2022年 第16卷 第8期   页码 1165-1197 doi: 10.1007/s11705-021-2120-4

摘要: Enhanced oil recovery (EOR) has been widely used to recover residual oil after the primary or secondary oil recovery processes. Compared to conventional methods, chemical EOR has demonstrated high oil recovery and low operational costs. Nanofluids have received extensive attention owing to their advantages of low cost, high oil recovery, and wide applicability. In recent years, nanofluids have been widely used in EOR processes. Moreover, several studies have focused on the role of nanofluids in the nanofluid EOR (N-EOR) process. However, the mechanisms related to N-EOR are unclear, and several of the mechanisms established are chaotic and contradictory. This review was conducted by considering heavy oil molecules/particle/surface micromechanics; nanofluid-assisted EOR methods; multiscale, multiphase pore/core displacement experiments; and multiphase flow fluid-solid coupling simulations. Nanofluids can alter the wettability of minerals (particle/surface micromechanics), oil/water interfacial tension (heavy oil molecules/water micromechanics), and structural disjoining pressure (heavy oil molecules/particle/surface micromechanics). They can also cause viscosity reduction (micromechanics of heavy oil molecules). Nanofoam technology, nanoemulsion technology, and injected fluids were used during the EOR process. The mechanism of N-EOR is based on the nanoparticle adsorption effect. Nanoparticles can be adsorbed on mineral surfaces and alter the wettability of minerals from oil-wet to water-wet conditions. Nanoparticles can also be adsorbed on the oil/water surface, which alters the oil/water interfacial tension, resulting in the formation of emulsions. Asphaltenes are also adsorbed on the surface of nanoparticles, which reduces the asphaltene content in heavy oil, resulting in a decrease in the viscosity of oil, which helps in oil recovery. In previous studies, most researchers only focused on the results, and the nanoparticle adsorption properties have been ignored. This review presents the relationship between the adsorption properties of nanoparticles and the N-EOR mechanisms. The nanofluid behaviour during a multiphase core displacement process is also discussed, and the corresponding simulation is analysed. Finally, potential mechanisms and future directions of N-EOR are proposed. The findings of this study can further the understanding of N-EOR mechanisms from the perspective of heavy oil molecules/particle/surface micromechanics, as well as clarify the role of nanofluids in multiphase core displacement experiments and simulations. This review also presents limitations and bottlenecks, guiding researchers to develop methods to synthesise novel nanoparticles and conduct further research.

关键词: nanofluid     EOR mechanism     nanoparticle adsorption     interface property     internal property    

Floret-like Fe–N nanoparticle-embedded porous carbon superstructures from a Fe-covalent triazine polymer

《化学科学与工程前沿(英文)》 2023年 第17卷 第5期   页码 525-535 doi: 10.1007/s11705-022-2232-5

摘要: Fe–Nx nanoparticles-embedded porous carbons with a desirable superstructure have attracted immense attention as promising catalysts for electrochemical oxygen reduction reaction. Herein, we employed Fe-coordinated covalent triazine polymer for the fabrication of Fe–Nx nanoparticle-embedded porous carbon nanoflorets (Fe/N@CNFs) employing a hypersaline-confinement-conversion strategy. Presence of tailored N types within the covalent triazine polymer interwork in high proportions contributes to the generation of Fe/N coordination and subsequent Fe–Nx nanoparticles. Owing to the utilization of NaCl crystals, the resultant Fe/N@CNF-800 which was generated by pyrolysis at 800 °C showed nanoflower structure and large specific surface area, which remarkably suppressed the agglomeration of high catalytic active sites. As expect, the Fe/N@CNF-800 exhibited unexpected oxygen reduction reaction catalytic performance with an ultrahigh half-wave potential (0.89 V vs. reversible hydrogen electrode), a dominant 4e transfer approach and great cycle stability (> 92% after 100000 s). As a demonstration, the Fe/N-PCNF-800-assembled zinc–air battery delivered a high open circuit voltage of 1.51 V, a maximum peak power density of 164 mW·cm–2, as well as eminent rate performance, surpassing those of commercial Pt/C. This contribution offers a valuable avenue to exploit efficient metal nanoparticles-based carbon catalysts towards energy-related electrocatalytic reactions and beyond.

关键词: Fe–Nx nanoparticles     hypersaline-confinement conversion     floret-like carbon     covalent triazine polymers     oxygen reduction reaction    

Decoration of CdMoO micron polyhedron with Pt nanoparticle and their enhanced photocatalytic performance

《化学科学与工程前沿(英文)》 2023年 第17卷 第12期   页码 1949-1961 doi: 10.1007/s11705-023-2360-6

摘要: This study aimed to prepare and apply a novel Pt/CdMoO4 composite photocatalyst for photocatalytic N2 fixation and tetracycline degradation. The Pt/CdMoO4 composite was subjected to comprehensive investigation on the morphology, structure, optical properties, and photoelectric chemical properties. The results demonstrate the dispersion of Pt nanoparticles on the CdMoO4 surface. Close contact between CdMoO4 and Pt was observed, resulting in the formation of a heterojunction structure at their contact region. Density functional theory calculation and Mott-Schottky analysis revealed that Pt possesses a higher work function value than CdMoO4, resulting in electron drift from CdMoO4 to Pt and the formation of a Schottky barrier. The presence of this barrier increases the separation efficiency of electron-hole pairs, thereby improving the performance of the Pt/CdMoO4 composite in photocatalysis. When exposed to simulated sunlight, the optimal Pt/CdMoO4 catalyst displayed a photocatalytic nitrogen fixation rate of 443.7 μmol·L‒1·g‒1·h‒1, which is 3.2 times higher than that of pure CdMoO4. In addition, the composite also exhibited excellent performance in tetracycline degradation, with hole and superoxide species identified as the primary reactive species. These findings offer practical insights into designing and synthesizing efficient photocatalysts for photocatalytic nitrogen fixation and antibiotics removal.

关键词: photocatalytic N2 fixation     Pt/CdMoO4     tetracycline degradation     Schottky barrier    

δ-TRIP 钢的物理与力学冶金

易红亮,陈蓬,王国栋,马鸣图

《中国工程科学》 2014年 第16卷 第2期   页码 18-30

摘要:

δ-相变诱发塑性(TRIP)钢具有高的强韧性,可达到第三代汽车钢性能要求,且可电阻点焊,是一种新型的具有较高产业化前景的先进汽车钢。主要阐述了δ-TRIP钢的发展、组织与性能、相变与组织演化机理、强韧性机理、电阻点焊工艺与物理冶金机理。

关键词: TRIP钢     δ铁素体     贝氏体相变     组织演化     性能    

A Pt-Bi bimetallic nanoparticle catalyst for direct electro-oxidation of formic acid in fuel cells

Shu-Hong LI, Yue ZHAO, Jian CHU, Wen-Wei LI, Han-Qing YU, Gang LIU, Yang-Chao TIAN

《环境科学与工程前沿(英文)》 2013年 第7卷 第3期   页码 388-394 doi: 10.1007/s11783-012-0475-y

摘要: Direct formic acid fuel cells are a promising portable power-generating device, and the development of efficient anodic catalysts is essential for such a fuel cell. In this work Pt-Bi nanoparticles supported on micro-fabricated gold wire array substrate were synthesized using an electrochemical deposition method for formic acid oxidation in fuel cells. The surface morphology and element components of the Pt-Bi/Au nanoparticles were characterized, and the catalytic activities of the three Pt-Bi/Au nanoparticle electrodes with different Pt/Bi ratios for formic acid oxidation were evaluated. It was found that Pt Bi /Au had a much higher catalytic activity than Pt Bi /Au and Pt Bi /Au, and Pt Bi /Au exhibited a current density of 2.7 mA·cm , which was 27-times greater than that of Pt/Au. The electro-catalytic activity of the Pt-Bi/Au electrode for formic acid oxidation increased with the increasing Bi content, suggesting that it would be possible to achieve an efficient formic acid oxidation on the low Pt-loading. Therefore, the Pt-Bi/Au electrode offers a promising catalyst with a high activity for direct oxidation of formic acid in fuel cells.

关键词: catalyst     electrochemical deposition     formic acid oxidation     fuel cell     gold wire array     microfabrication    

标题 作者 时间 类型 操作

Influences of spinel type and polymeric surfactants on the size evolution of colloidal magnetic nanocrystals (MFe

Tahereh R. BASTAMI,Mohammad H. ENTEZARI,Chiwai KWONG,Shizhang QIAO

期刊论文

Activated carbon induced oxygen vacancies-engineered nickel ferrite with enhanced conductivity for supercapacitor

期刊论文

A novel algorithm for frequency dependent modeling of ferrite ring and its optimum design to study VFTO

Mehrdad MAJIDI, Hamid JAVADI, Moein MANBACHI

期刊论文

Performance of iron-air battery with iron nanoparticle-encapsulated C–N composite electrode

期刊论文

Effect of noble metal nanoparticle size on C–N bond cleavage performance in hydrodenitrogenation: a study

期刊论文

Iron oxide nanoparticle-based theranostics for cancer imaging and therapy

Xiaoqing REN,Hongwei CHEN,Victor YANG,Duxin SUN

期刊论文

Nanoparticle-enhanced coolants in machining: mechanism, application, and prospects

期刊论文

Cobalt nanoparticle decorated N-doped carbons derived from a cobalt covalent organic framework for oxygen

期刊论文

Cobalt-nanoparticle catalysts derived from zeolitic imidazolate framework@MXene composites for efficient

期刊论文

A mini-review of ferrites-based photocatalyst on application of hydrogen production

期刊论文

A review on the application of nanofluids in enhanced oil recovery

期刊论文

Floret-like Fe–N nanoparticle-embedded porous carbon superstructures from a Fe-covalent triazine polymer

期刊论文

Decoration of CdMoO micron polyhedron with Pt nanoparticle and their enhanced photocatalytic performance

期刊论文

δ-TRIP 钢的物理与力学冶金

易红亮,陈蓬,王国栋,马鸣图

期刊论文

A Pt-Bi bimetallic nanoparticle catalyst for direct electro-oxidation of formic acid in fuel cells

Shu-Hong LI, Yue ZHAO, Jian CHU, Wen-Wei LI, Han-Qing YU, Gang LIU, Yang-Chao TIAN

期刊论文