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Journal of Materials Science & Technology 2021年第22期81卷 162-174页

作者： xuemin yin Hejun Li Ruimei Yuan Jinhua Lu State Key Laboratory of Solidification Processing Shaanxi Province Key Laboratory of Fiber Reinforced Light Composite MaterialsCarbon/Carbon Composites Research CenterNorthwestern Polytechnical UniversityXi’an710072China

To overcome the disadvantages of traditional powder electrodes,such as the insufficient performance,the aggregation of active materials,and the complex fabrication process,rationally constructing free-standing electrode materials with hierarchical architecture is an effective and promising method,which could further improve the electrochemical ***,using metal-organic framework nanoarrays(MOFNAs)as self-sacrificial templates and SiC nanowires(SiCNWs)network as nanoscale conductive skeletons,we successfully fabricated the hierarchical core-shell SiCNWs@NiCo_(2)O_(4)NAs on carbon cloth(CC)*** advantages of structural merits,such as hierarchical porous triangle-like NiCo_(2)O_(4)NAs,the interwoven SiCNWs network and conductive CC substrate,when evaluated as a binder-free supercapacitor electrode,the CC/SiCNWs@NiCo_(2)O_(4)NAs shows a high specific capacitance of 1604.7 F g^(-1)(specific capacity of 222.9 mA h g^(-1))at 0.5 A g^(-1),good rate performance,and excellent cycling ***,the hybrid supercapacitor assembled with CC/SiCNWs@NiCo_(2)O_(4)NAs as the cathode and MOF derived CC/SiCNWs@CNAs as the anode,could deliver a high specific density of 49.9 W h kg^(-1) at a specific power of 800 W kg^(-1),stable cycling performance,and good ***,this feasible strategy for fabricating hierarchical structure displays great potential in the field of energy storage.

关键词： Metal-organic framework SiC nanowire NiCo_(2)O_(4) Flexible hybrid supercapacitors

NiCoLDH nanosheets grown on MOF-derived Co_(3)O_(4) triangle nanosheet arrays for high-performance supercapacitor

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Journal of Materials Science & Technology 2021年第3期62卷 60-69页

作者： xuemin yin Hejun Li Ruimei Yuan Jinhua Lu State Key Laboratory of Solidification Processing Carbon/Carbon Composites Research CenterNorthwestern Polytechnical UniversityXi’an 710072China

Hierarchical Co_(3)O_(4)@NiCoLDH nanosheets(NSs)were prepared on carbon cloth through a multistep method,containing Metal-organic frameworks(MOF)-templated thermal annealing and *** triangle-shaped Co_(3)O_(4 NSs)were firstly obtained by thermal treatment of MOF templates in ***,ultrathin NiCoLDH_(NSs)were in-situ electrodeposited on the surface of Co_(3)O_(4NSs),constructing a core-shell *** the unique hierarchical structure,high conductivity of Co_(3)O_(4 NSs)core and large surface area of NiCoLDHNSs shell,the Co_(3)O_(4)@NiCoLDH_(NSs)array served as supercapacitor electrode exhibits excellent electrochemical properties,such as high specific capacitance of 1708 F g^(-1)(850 C g^(-1))at a current density of 1 A g^(-1),good rate capability,and excellent cycling ***,the asymmetric supercapacitor assembled by Co_(3)O_(4)@NiCoLDH_(NSs)and activated carbon,also displays superior electrochemical perfo rmance with high energy density and power ***,the strategy of constructing core-shell structure based on MOF templates could be extended to other electrochemical fields.

关键词： NiCoLDH Co_(3)O_(4) Core-shell Supercapacitor MOF

Effects of PyC shell thickness on the microstructure,ablation resistance of SiCnws/PyC-C/C-ZrC-SiC composites

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Journal of Materials Science & Technology 2021年第12期71卷 55-66页

作者： Qinchuan He Hejun Li xuemin yin Jinhua Lu College of Materials and Chemistry&Chemical Engineering Chengdu University of TechnologyChengdu 610059China Carbon/Carbon Composites Research Center Northwestern Polytechnical UniversityXi’an710072China

SiC nanowires/pyrocarbon(SiCnws/PyC)core-shell structure toughenedC/C-ZrC-SiC composites were fabricated by CLVD process,and the influences of PyC shell thickness on the microstructure and ablation resistance of the composites were *** results presented that SiCnws/PyC core-shell structure had a linear shape,and the composites became dense with the increasing PyC *** the thickness of PyC shell increased from 0 to 2.4μm,the density and thermal conductivity of the composites was improved gradually,but the coefficient of thermal expansion(CTE)decreased firstly and then *** the ablation test for 90 s,the ablation rates of the composites decreased continuously as the PyC thickness increased from 0 to 1.4μm,but increased when the PyC thickness was up to 2.4μ*** when the PyC thickness was 1.4μm,the linear and mass ablation rates of the composites were 71.25%and 63.01%lower than those of the composites without PyC *** reasons behind the remarkable improvement of anti-ablation property were that the proper PyC thickness could alleviate the CTE mismatch to promote the formation of complete oxide coating,improve the thermal conductivity to reduce heat corrosion and enhance the capability to limit the mechanical erosion.

关键词： SiCnws/PyC core-shell structure C/C-ZrC-SiC composites Microstructure Ablation resistance CLVD

Flexible double-wall carbon foam/Cu-Co oxides based symmetric supercapacitor with ultrahigh energy density

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Journal of Materials Science & Technology 2023年第29期160卷 109-117页

作者： Ruimei Yuan xuemin yin Shengyue Gu Jingjing Chang Hejun Li Advanced Interdisciplinary Research Center for Flexible Electronics Xidian UniversityXi’an 710071China Carbon/Carbon Composites Research Center Northwestern Polytechnical UniversityXi’an 710072China School of Science XI’AN University of Posts&TelecommunicationsXi’an 710121China

Electrochemical supercapacitors are regarded as a promising electrochemical energy storage device,because of its fast chargeability,long cycle life,and high power *** connection of porous carbon and extensive electroactive substances have significantly improved their ***,the unsuitable constructing strategy and unclear electrochemical mechanism lead to a mismatch between the fast double-layer effect and the sluggish Faradaic behavior at the electrode,degrading the energy density and capacitance ***,the construction strategy based on the double-wall carbon foam,carbon nanotubes and copper nanocubes provides enhanced electronic structure and ion transport path,resulting in accelerated proton transport and redox insertion/deinsertion processes,as well as surprising electrochemical behaviors of Cu-Co oxide on both positive and negative electrodes(927.9 and 427.0 F g^(−1)at 1 A g^(−1)).A flexible symmetric supercapacitor assembled with the SCF/CNT@Cu/Cu-Co-O delivers a extremely excellent *** 1 A g^(−1),the specific capacitance is 337.8 F g^(−1),the energy density hits 60 Wh kg^(−1)at the power density of 17.8 kW kg^(−1).At 10 A g^(−1),the energy density is up to 120.1 Wh kg^(−1),representing the top energy density of *** systematical structural optimization and mechanism study,this work broadens the fabricating strategy of hierarchical nanostructures and high-performance electrode materials for energy storage.

关键词： Carbon foam Cu-Co oxides Symmetric supercapacitors Energy density

Stable controlled growth of 3D CuO/Cu nanoflowers by surfactant-free method for non-enzymatic hydrogen peroxide detection

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Journal of Materials Science & Technology 2018年第9期34卷 1692-1698页

作者： Ruimei Yuan Hejun Li xuemin yin Leilei Zhang Jinhua Lu State Key Laboratory of Solidification Processing Carbon/Carbon Composites Research Center Northwestern Polytechnical University

Sensitive, convenient and rapid detection of hydrogen peroxide（H2 O2） is highly desirable in fields like fundamental biological research, food industries, and clinical environmental analysis. Herein, a hierarchical porous CuO/Cu flower-like active electrode material for non-enzymatic H2 O2 sensor was synthesized via a low-cost and one-step chemical oxidation of Cu powder in water bath without surfactants. In order to discuss the growth mechanism of the product, products with different growth time length were fabricated. The electro-catalysis of all products were first exhibited by cyclic-voltammetry,and the product under 6 h reaction shows the best result. The detailed electro-catalytic behaviors of the best product（under 6 h reaction） are characterized by cyclic-voltammetry and amperometry under alkaline conditions. The materials have high sensitivity of 103 μA mM^（-1） cm^（-2）（R^2= 0.9979）, low detection limit of 2 μmol/L and wide concentration range（from 2 μmol/L to 19.4 mmol/L）. Large specific surface area and stabled nanostructure enabled good features, such as stability and sensitivity for the H2 O2 determination.

关键词： CuO nanoparticles Surfactant-free Electrical properties Sensors H2O2

Effects of electroacupuncture versus nimodipine on long-term potentiation and synaptophysin expression in a rat model of vascular dementia

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Neural Regeneration Research 2011年第30期6卷 2357-2361页

作者： Dengming Wei xuemin Jia Xiangxu yin Wenwen Jiang Department of Pathology Medical School of Ningbo University Ningbo 315211 Zhejiang Province China

The present study stimulated Baihui （DU 20） and Dazhui （DU 14） acupoints in a rat model of vascular dementia with electroacupuncture to investigate changes in long-term potentiation and synaptophysin expression in the hippocampus. The results revealed that synaptophysin expression in brain tissues was increased after electroacupuncture. After high4requency stimulation, the population spike latency was shortened and the excitatory postsynaptic potential slope and population spike amplitude were increased. In addition, cognitive function was enhanced, similar to the effects of intragastric perfusion of nimodipine. The results indicated that electroacupuncture at Baihui and Dazhui acupoints can improve learning and memory functions of a rat model of vascular dementia by promoting synaptophysin expression, enhancing hippocampal synaptic plasticity and accelerating synaptic transmission.

关键词： vascular dementia electroacupuncture learning and memory ability long-term potentiation synaptophysin neural regeneration

Construction of multi-structures based on Cu NWs-supported MOF-derived Co oxides for asymmetric pseudocapacitors

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Journal of Materials Science & Technology 2021年第6期65卷 182-189页

作者： Ruimei Yuan Hejun Li xuemin yin Peipei Wang Jinhua Lu Leilei Zhang State Key Laboratory of Solidification Processing Carbon/Carbon Composites Research CenterNorthwestern Polytechnical UniversityXi'an 710072China

Cu@MOF core-shell nanowires are synthesized by introducing oxidizable and CTAB-modified metal nanowires as self-engaged templates and supporting MOFs for a one-dimension *** following thermal process is controlled to obtain several one-dimension structure s ofCuCo-mixed materials,such as nanorods,single-shell and double-shell *** hollow structure for electrode materials enlarges the surface area,provides buffer space for electrolyte to accelerate the ion/charge transfers and for the structure to reduce injuries of volume expansion during *** with some other merits,such as adequate oxidation of the MOFs,small crystal grains of the material,and well-mixed Cu/Co oxides,the double-shell Cu@MOF nanowires(CuCo-DS5)applied for pseudocapacitors deliver advanced electrochemical performance with a specific capacitance of 563.8 F g^(-1)at 1 A g^(-1)as well as an outstanding cycling stability with a 92%retention after 3000 cycles at 5 A g^(-1).Meanwhile,an asymmetric pseudocapacitor constructed with the CuCo-DS5 and active carbon(AC)shows a high specific capacitance and energy density.

关键词： Modified nanowires MOF-derived Hollow Core-shell Double-shell Energy storage

Grow defect-rich bamboo-like carbon nanotubes on carbon black for enhanced microwave absorption properties in X band

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Journal of Materials Science & Technology 2022年第24期119卷 200-208页

作者： Yameng Jiao Qiang Song xuemin yin Liyuan Han Wei Li Hejun Li State Key Laboratory of Solidification Processing Shannxi Province Key Laboratory of Fiber Reinforced Light Composite MaterialsCarbon/Carbon Composites Research CenterNorthwestern Polytechnical UniversityXi’an 710072China

Due to the limited electromagnetic wave(EMW)loss capacity and agglomeration,carbon black(CB)gradually fails to meet the increasingly harsh demanding ***,defect-rich bamboo-like carbon nanotubes(CNTs)were grown on CB by the process of chemical vapor *** prepared in situ on CB can assist it to build a developed multilevel conductive network and introduce plentiful CB/CNTs ***’s more,the defects that accompany the growth of CNTs endow CNTs with a moderate conductivity and good impedance matching,thereby causing an effective microwave absorption(MA).Meanwhile,the high-density defects on CNTs can induce dipole polarization to further strengthen the EMW loss *** influence of CNTs with different growth time on MA performance has been *** from the structural merits,the synthesized CB-CNT with CNTs growth time of 40 min exhibits the optimal absorbing property,which has the minimum reflection loss of-53.6 d B and maximum effective absorption bandwidth of 4.1 GHz with the thickness of 2.7 mm,covering almost the entire X *** introduction of defect-rich CNTs significantly enhances the EMW loss ability of CB,which provides a rational strategy for the design of high-efficient microwave absorption materials.

关键词： Microwave absorption Carbon nanotubes Defect-rich Conductive network Interface polarization

Deep understanding of typical CNT morphology on the microstructure and mechanical properties of 2D carbon/carbon composites

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Journal of Materiomics 2024年第2期10卷 396-407页

作者： Jiajia Sun Qiang Song Liyuan Han xuemin yin Hejun Li State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of Fiber Reinforced Light Composite MaterialsNorthwestern Polytechnical UniversityXi'an710072China

For the inadequate interlaminar strength of 2D carbon/carbon(C/C)composite,in-situ grown carbon nanotubes(CNTs)reinforcing strategy was put forward to strengthen the interlaminar matrix at the nanoscale and inhibit the interlaminar *** morphology is an essential factor in influencing the enhancement ***,the influence of in-situ grown CNT morphology on the microstructure and mechanical properties of C/C composite was deeply *** radially-aligned straight CNTs could induce the formation of highly-ordered pyrolytic carbon(PyC),while PyC in randomly-distributed curved CNTs concentrated area exhibits an isotropic ***,radially-aligned straight CNTs show better improvement on the flexural and shear strength of C/C *** to the fine structural characterization and finite element simulation,the influence mechanism of CNT morphology was *** morphology can influence the stress distribution in the PyC protective layer,and compared with radially-aligned straight CNTs,randomly-distributed curved CNTs induce higher tensile stress in the PyC protective layer,which has a detrimental impact on the flexural and shear properties of C/C *** work provides novel insights into the effect of CNT morphology on the microstructure and mechanical properties of C/C composites,which gives a basis for the structural design and preparation of CNTs reinforced C/C composites.

关键词： CNT morphology C/C composite Microstructure Mechanical properties

Two birds with one stone: Simultaneous fabrication of HfC nanowires and CNTs through efficient utilization of polymer-derived ceramics

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Journal of Materials Science & Technology 2022年第34期129卷 163-172页

作者： Yanqin Fu Yulei Zhang xuemin yin Liyuan Han Qiangang Fu Hejun Li Ralf Riedel Shaanxi Province Key Laboratory of Fiber Reinforced Light Composite Materials Northwestern Polytechnical UniversityXi’an 710072China Technische Universität Darmstadt Institut für MaterialwissenschaftOtto-Berndt-Straβe 3Darmstadt D-64287Germany

Carbon nanotubes(CNTs) are fabricated in carbon cloth by ultilizing the waste gasses when fabricating hafnium carbide nanowires(HfC_(NWS)) through thermal pyrolysis of Hf-containing polymer *** formed HfC_(NWS) are distributed uniformly on the surface of the carbon fibers in carbon/carbon(C/C) composites and display perfect single crystal *** pyrolysis of the Hf-containing organic precursor provides hafnium and carbon source for the growth of HfC_(NWS).The released waste gasses containing CO,CH4and CO_(2)are the main carbon source for the growth of ***,the flexural strength of HfC_(NWS) reinforced carbon/carbon(HfC_(NWS)-C/C) composites is enhanced by ~105% compared with pure C/C,and the CNTs/carbon cloth also displays improved electrochemical performance with respect to capacitor *** present study introduces a novel sustainable and eco-friendly process related to polymer-derived ceramics to form advanced ceramic nanocomposites and proposes a deep understanding of the growth mechanism of CNTs.

关键词： HfC nanowires Carbon nanotubes Waste gasses Effective utilization Polymer-derived ceramics