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Influence of La^(3+) and Dy^(3+) on the properties of the long afterglow phosphor CaAl_2O_4: Eu^(2+), Nd^(3+)

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Rare Metals 2008年第4期27卷 335-339页

作者： TENG Xiaoming ZHUANG weidong he Huaqiang National Engineering Research Center for Rare Earth Materials General Research Institute for Nonferrous Metals and Grirem Advanced Materials Co. Ltd. Beijing 100088 China

The long afterglow phosphor CaAl2O4： Eu^2＋, Nd^3＋ was prepared by the high temperature solid-state reaction method, and the influence of La^3＋ and Dy^3＋ on the properties of the long afterglow phosphor was studied by X-ray diffiaction （XRD）, photoluminescence （PL）, and thermoluminescence （TL）. The XRD pattem shows the host phase of CaAl2O4 is produced and no impurity phase appears. The peak wavelength of the phosphor does not vary with La^3＋ and Dy^3＋ doping. It implies that the crystal field, which affects the 5d electron states of Eu^2＋, is not changed dramatically after doping of La^3＋ and Dy^3＋. The TL spectra indicate that the phosphor doped with La^3＋ or Dy^3＋ produces different depths of trap energy level. In the mechanism of long afterglow luminescence, it is considered that La^3＋ or Dy^3＋ works as trap energy level. The decay time lies on the number of electrons in the trap energy level and the rate of the electrons returning to the excitation level.

关键词： rare earth aluminate long afterglow phosphor electron traps

Self-supported metal(Fe, Co, Ni)-embedded nitrogen-doping carbon nanorod framework as trifunctional electrode for flexible Zn-air batteries and switchable water electrolysis

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Green Energy & Environment 2023年第6期8卷 1644-1653页

作者： Qiuyan Jin Liping Xiao weidong he Hao Cui Chengxin Wang State Key Laboratory of Optoelectronic Materials and Technologies School of Materials Science and EngineeringSun Yat-sen UniversityGuangzhou510275China The Key Laboratory of Low-Carbon Chemistry&Energy Conservation of Guangdong Province Sun Yat-sen UniversityGuangzhou510275China

To meet the practical demand of wearable/portable electronics, developing high-efficiency and durable multifunctional catalyst and in-situ assembling catalysts into electrodes with flexible features are urgently needed but challenging. herein, we report a simple route to fabricate bendable multifunctional electrodes by in-situ carbonization of metal ion absorbed polyaniline precursor. Alloy nanoparticles encapsulated in graphite layer are uniformly distributed in the N-doping carbon nanorod skeleton. Profiting from the favorable free-standing structure and the cooperative effect of metallic nanoparticles, graphitic layer and N doped-carbon architecture, the trifunctional electrodes exhibit prominent activities and stability toward heR, OER and ORR. Notably, due to the protection of carbon layer, the electrocatalysts show the reversible catalytic heR/OER properties. The overall water splitting device can continuously work for 12 h under frequent exchanges of cathode and anode. Importantly, the bendable metal air batteries fabricated by self-supported electrode not only displays the outstanding battery performance,achieving a decent peak power density(125 mW cm^(-2)) and exhibiting favorable charge-discharge durability of 22 h, but also holds superb flexible stability. Specially, a lightweight self-driven water splitting unit is demonstrated with stable hydrogen production.

关键词： Trifunctional catalysts Self-supported electrodes Switchable water splitting Flexible Zn-air battery Self-powered system

Dynamic Logic in Control

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Journal of Systems Engineering and Electronics 1994年第3期5卷 20-31页

作者： he, weidong Yu, Xinyao Chen, Zhongji Zhang, Minglian Beijing Univ of Aeronautics & Astronautics Beijing China

For the dynamic property in the control system, in this paper we advance dynamic logic to analyze and synthesize the control problems. This approach is similar to the way in which people always resolve such problems, and it can reflect the nature of the system. The dynamic logic combines the people's logic analysis with the dynamic property of the control system. On the basis of the dynamic logic qualitative model, the analyzing process and synthesizing process may go on. So there are many of the non-linear and logic factors which can be directly taken into consideration in the analyzing and designing process. The combination of the human intelligence and artificial intelligent techniques with the conventional methods of analysis and design, has provide an effective tool for the qualitative analysis and the qualitative design of the intelligent control system. We have successfully resolved the stabilizing problem of the inverted pendulum with dynamic logic.

关键词： Artificial intelligence Control system analysis Control system synthesis Intelligent control Mathematical models System stability

A surfactant-modified composite separator for high safe lithium ion battery

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Journal of Energy Chemistry 2023年第1期76卷 398-403,I0010页

作者： Botao Yuan Niandong he Yifang Liang Liwei Dong Jipeng Liu Jiecai Han weidong he Yuanpeng Liu National Key Laboratory of Science and Technology on Advanced Composites in Special Environments Center for Composite Materials and StructuresHarbin Institute of TechnologyHarbin 150080HeilongjiangChina MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage School of Chemistry and Chemical EngineeringHarbin Institute of TechnologyHarbin 150080HeilongjiangChina Chongqing Research Institute Harbin Institute of TechnologyChongqing 401151China

Separators have been gaining increasing attention to improve the performance of lithium ion batteries(LIBs),especially for high safe and long cycle ***,commercial polyolefin separators still face the problems of rapid capacity decay and safety issues due to the poor wettability with electrolytes and low thermal ***,a novel composite separator is proposed by introducing a surfactant of sodium dodecyl thiosulfate(SDS)into the polytetrafluoroethylene(PTFE)substrate with the binder of polyacrylic acid(PAA)through the suction filtration *** introduction of PAA/SDS enhances the adsorption energy between PTFE substrate and electrolyte through density functional theory calculations,which improves wettability and electrolyte uptake of the separator *** asachieved composite separator enables the LIBs to own high Li^(+)conductivity(0.64×10^(-3)S cm^(-1))and Li^(+)transference number(0.63),further leading to a high capacity retention of 93.50%after 500 cycles at 1 *** addition,the uniform and smooth surface morphology of Li metal employed the composite separator after cycling indicates that the lithium dendrites can be successfully *** work indicates a promising route for the preparation of a novel composite separator for high safe LIBs.

关键词： Composite separator PTFE Surfactant High safe Lithium ion batteries

Modeling and simulation of solvent behavior and temperature distribution within long stick propellants with large web thickness undergoing drying

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Defence Technology（防务技术） 2023年第10期28卷 42-55页

作者： Enfa Fu Qianling Liu Yu Luan Yao Zhu weidong he Zhenggang Xiao Key Laboratory of Special Energy Materials Ministry of EducationSchool of Chemistry and Chemical EngineeringNanjing University of Science and TechnologyNanjing210094People's Republic of China

Drying is a complicated physical process which involves simultaneous heat and mass transfer in the removal of solvents inside *** drying techniques may result in the formation of a hard skin layer near the surface to block the free access of most solvent through for long stick propellants with large web thickness,which lead to lower drying efficiency and worse drying *** study aims to gain a comprehensive understanding of drying process and clarify the mechanism of the blocked layer near the propellant surface.A new three-dimensional coupled heat and mass transfer(3D-CHMT)model was successfully developed under transient *** drying experiment results show that the 3DCHMT model could be applied to describe the drying process well since the relative error of the content of solvent between simulation and experiment values is only 5.5%.The solvent behavior simulation demonstrates that the mass transfer process can be divided into super-fast(SF)and subsequent minorfast(MF)stages,and the SF stage is vital to the prevention of the blocked layer against the free access for solvent molecules inside propellant *** effective solvent diffusion coefficient(Deff)of the propellant surface initially increases from 3.4×10^(-6)to 5.3×10^(-6)m^(2)/s as the temperature increases,and then decreases to 4.1×10^(-8)m^(2)/s at 60-100 *** value of Deffof surface between 0-1.4 mm has a unique trend of change compared with other regions,and it is much lower than that of the internal at100 min under simulation ***,the temperature of the propellant surface increases rapidly at the SF stage(0-100 min)and then very slowly *** the evolution of Deffand temperature distribution demonstrate that the blocked layer near the propellant surface has been formed in the time period of approximately 0-100 min and its thickness is about 1.4 *** mitigate the formation of blocked layer and improve its drying quality of finial prop

关键词： Stick propellants Drying Large web thickness 3D numerical modeling heat transfer Solvent behavior

Hierarchical Ni-Co-S@Ni-W-O core-shell nanosheet arrays on nickel foam for high-performance asymmetric supercapacitors

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Nano Research 2018年第3期11卷 1415-1425页

作者： weidong he Zhifu Liang Keyu ji Qingfeng Sun Tianyou Zhai Xijin Xu School of Physics and Technology University of Jinan 336 West Road of Nan Xinzhuang Jinan 250022 China State Key Laboratory of Material Processing and Die & Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology (HUST) Wuhan 430074 China School of Engineering Zhejiang A & F University Hangzhou 311300 China

Nickel cobalt sulfides （Ni-Co-S） have attracted extensive attention for application in electronic devices owing to their excellent conductivity and high electrochemical capacitance. To facilitate the large-scale practical application of Ni-Co-S, the excellent rate capability and cyclic stability of these compounds must be fully exploited. Thus, hierarchical Ni-Co-S@Ni-W-O （Ni-Co-S-W） core/shell hybrid nanosheet arrays on nickel foam were designed and synthesized herein via a facile three-step hydrothermal method, followed by annealing in a tubular furnace under argon atmosphere. The hybrid structure was directly assembled as a free-standing electrode, which exhibited a high specific capacitance of 1,988 F·g^-1 at 2 A·g^-1 and retained an excellent capacitance of approximately 1,500 F·g^-1 at 30 A·g^-1, which is superior to the performance of the pristine Ni-Co-S nanosheet electrode. The assembled asymmetric supercapacitors achieved high specific capacitance （155 F·g^-1 at 1 A·g^-1）, electrochemical stability, and a high energy density of 55.1 W·h·kg^-1 at a power density of 799.8 W·kg^-1 with the optimized Ni-Co-S-W core/shell nanosheets as the positive electrode, activated carbon as the negative electrode, and 6 M KOH as the electrolyte.

关键词： core/shell structure free-standing electrode supercapacitors high energy density excellent stability

Valence modulated nickel oxynitride network as integrated bifunctional electrodes for enhanced energy storage

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Journal of Energy Chemistry 2021年第5期30卷 56-63页

作者： Shouzhi Wang hengshuai Li weidong he hehe Jiang Yongliang Shao Yongzhong Wu Xiaopeng Hao State Key Lab of Crystal Materials Shandong UniversityJinan 250100ShandongChina School of Mechanical&Automotive Engineering Liaocheng UniversityLiaocheng 252000ShandongChina

As promising electrode materials,transition metal oxides have attracted considerable attention owing to their excellent performance in electrochemical energy ***,their poor conductivity and fragile structure limit their practical *** this study,a binder-free nickel oxide/oxynitride network(NiON WS)bifunctional electrodes with cation multivalent states that exhibit high energy storage performance were synthesized for the first *** massive active sites,high specific surface areas,and multiple cation valence states of NiON WS were advantageous for electrochemical redox reaction during its application in supercapacitors(1283.5 mF cm^(-2))and lithium-ion batteries(1345.0 mA h g^(-1)).Particularly,the NiON WS based flexible asymmetric SCs exhibit excellent capacitance and energy ***-principle calculations were employed to study the mechanism of the electrochemical performance improvement of NiON *** study demonstrates the potential of transition metal oxides electrode with high capacity and activity for electrochemical energy storage and conversion.

关键词： Nickel oxynitride Bifunctional electrodes Flexible supercapacitors Lithium-ion battery First-principle calculation

Self-standing hollow porous Co/a-WO_(x)nanowire with maximum Mott-Schottky effect for boosting alkaline hydrogen evolution reaction

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Nano Research 2023年第4期16卷 4603-4611页

作者： Jianpo Chen Jianping Zheng weidong he Haikuan Liang Yan Li Hao Cui Chengxin Wang School of Materials Science and Engineering The Key Laboratory of Low-Carbon Chemistry&Energy Conservation of Guangdong ProvinceSun Yatsen UniversityGuangzhou 510275China

The sufficient utilization of Mott-Schottky effect for boosting alkaline hydrogen evolution reaction(heR)depends upon scale minimizing of interface components and exposure maximizing of Mott-Schottky ***,a self-standing porous tubular Mott-Schottky electrocatalyst is constructed by a self-template etching strategy,where amorphous WO_(x)(a-WO_(x))nano-matrix connects Co *** novel“Janus”electrocatalyst maximizes the Mott-Schottky effect by not only providing a highly exposed micro interface,but also simultaneously accelerating the water dissociation and optimizing the hydrogen desorption *** findings and theoretical calculations reveal that Co/a-WO_(x)Mott-Schottky heterointerface triggers the electron redistribution and a build-in electric field,which can not only optimize the adsorption energy of the reaction intermediates,but also facilitate the charge ***,Co/a-WO_(x)requires an overpotential of only 36.3 mV at 10 mA·cm^(−2)and shows a small Tafel slope of 53.9 mV·dec^(−1)as well as an excellent 200-h long-term *** work provides a novel design strategy for maximizing the Mott-Schottky effect on promoting alkaline heR.

关键词： Mott-Schottky effect electrocatalyst self-template etching hydrogen evolution reaction(heR) electron redistribution

Surface modification of CeO_(2-x) nanorods with Sn doping for enhanced nitrogen electroreduction

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Journal of Energy Chemistry 2023年第12期87卷 400-407,I0011页

作者： Yuhang Xiao Xiaohong Tan Yingying Guo Jianpo Chen weidong he Hao Cui Chengxin Wang School of Materials Science and Engineering Sun Yat-sen UniversityGuangzhou 510275GuangdongChina The Key Laboratory of Low-Carbon Chemistry&Energy Conservation of Guangdong Province Sun Yat-sen UniversityGuangzhou 510275GuangdongChina

While the electrochemical nitrogen reduction reaction(NRR) represents a prospective blueprint for environmentally renewable ammonia generation,it has yet to overcome the limitations of weak activity and inferior *** this regard,surface modification tactic was constructed to markedly enhance the activity and selectivity via introducing Sn atoms into the surface of defective cerium oxide(denoted as Sn-CeO_(2-x)) as the active and robust electrocatalyst for NRR under benign *** introduction of Sn atoms in CeO_(2-x)can not only inhibit the heR activity of the catalyst but also modulate the electronic structure of ceria and optimize N-Ce interaction,thus enhancing NRR activity and *** all previous CeO_(2)-based NRR catalysts,this catalyst has demonstrated an ammonia yield rate of 41.1 μg mg_(cat)^(-1) h^(-1) and an exceptional Faradic efficiency of 35.3%.This work presents a viable approach for the development of advanced NRR electrocatalysts.

关键词： Ceria-based materials Nitrogen reduction reaction Sn-doping Surface modification Electrocatalysis