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International Journal of Minerals,Metallurgy and Materials 2023年第6期30卷 1190-1197页

作者： Fuyuan Liang Jiaran Yang Haiqing Wang Junwei Wu School of Materials Science and Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China

Physical vapor deposition(PVD)can be used to produce high-quality Gd_(2)O_(3)-doped CeO2(GDC)films.Among various PVD methods,reactive sputtering provides unique benefits,such as high deposition rates and easy upscaling for industrial applications.GDC thin films were successfully fabricated through reactive sputtering using a Gd_(0.2)Ce_(0.8)(at%)metallic target,and their application in solid oxide fuel cells,such as buffer layers between yttria-stabilized zirconia(YSZ)/La0.6Sr0.4Co0.2Fe0.8O_(3−δ)and as sublayers in the steel/coating system,was evaluated.First,the direct current(DC)reactive-sputtering behavior of the GdCe metallic target was determined.Then,the GDC films were deposited on NiO-YSZ/YSZ half-cells to investigate the influence of oxygen flow rate on the quality of annealed GDC films.The results demonstrated that reactive sputtering can be used to prepare thin and dense GDC buffer layers without high-temperature sintering.Furthermore,the cells with a sputtered GDC buffer layer showed better electrochemical performance than those with a screen-printed GDC buffer layer.In addition,the insertion of a GDC sublayer between the SUS441 interconnects and the Mn-Co spinel coatings contributed to the reduction of the oxidation rate for SUS441 at operating temperatures,according to the area-specific resistance tests.

关键词： solid oxide fuel cell physical vapor deposition Gd2O3-doped CeO_(2) metallic interconnects electrical conductivity

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An iron-catalyzed multicomponent reaction of cycloketone oxime esters, alkenes, DABCO·(SO_(2))_(2) and trimethylsilyl azide

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Organic Chemistry Frontiers 2022年第4期9卷 917-922页

作者： Jun Zhang Junwei Wu Xiaotong Chang Peiqi Wang Jiemin Xia Jie wu School of Pharmaceutical and Materials Engineering&Institute for Advanced Studies Taizhou UniversityJiaojiang 318000ZhejiangChina State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of Sciences345 Lingling RoadShanghai 200032China School of Chemistry and Chemical Engineering Henan Normal UniversityXinxiang 453007China

An iron-catalyzed four-component reaction of cycloketone oxime esters,alkenes,DABCO·(SO_(2))_(2) and tri-methylsilyl azide(TMSN_(3))is described.This multicomponent radical transformation presents excellent regio-and chemoselectivity,leading to a range of β-azidosulfones in moderate to excellent yields.In this protocol,the utilization of a sulfur dioxide surrogate of DABCO·(SO_(2))_(2) as the source of the sulfonyl group enables the reaction to proceed efficiently under mild conditions without the need for strong oxidants.Additionally,the products can be transformed intoβ-aminosulfones and other valuable sulfonyl-contain-ing nitrogen heterocycles.

关键词： azide ketone esters

Effects of ancillary ligands in acceptorless benzyl alcohol dehydrogenation mediated by phosphine-free cobalt complexes

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Frontiers of Chemical Science and Engineering 2023年第3期17卷 314-325页

作者： Yan Xu Lu Wang Junwei Wu Guanzhong Zhai Daohua Sun Department of Chemical and Biochemical Engineering College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China Department of Chemical and Biochemical Engineering National Engineering Laboratory for Green Chemical Productions of Alcohols−Ethers−EstersCollege of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China Luoyang Ship Material Institute Luoyang 471039China

Acceptorless alcohol dehydrogenation stands out as one of the most promising strategies in hydrogen storage technologies.Among various catalytic systems for this reaction,cost-effective molecular catalysts using phosphine-free ligands have gained considerable attention.However,the central challenge for using non-precious metals is to overcome the propensity of reacting by oneelectron pathway.Herein,we synthesized a phosphine-freeη^(5)-C_(5)Me_(5)-Co complex by using the metal-ligand cooperative strategy and compared its activity with analogous catalysts toward acceptorless alcohol dehydrogenation.The catalyst showed excellent performance with a turnover number of 130.4 and a selectivity close to 100%.The improved performance among the class ofη^(5)-C_(5)Me_(5)-Co complexes could be attributed to the more accessible Co center and its cooperation with the redox-active ligand.To further study the systematic structure-activity relationship,we investigated the electronic structures ofη^(5)-C_(5)Me_(5)-Co complexes by a set of characterizations.The results showed that the redox-active ligand has a significant influence on theη^(5)-C_(5)Me_(5)-Co moiety.In the meantime,the proximal O−/OH group is beneficial for shuttling protons.For the catalytic cycle,two dehydrogenation scenarios were interrogated through density functional theory,and the result suggested that the outer-sphere pathway was preferred.The formation of a dihydrogen complex was the rate-determining step with aΔG value of 16.9 kcal∙mol‒1.The electron population demonstrated that theη^(5)-C_(5)Me_(5)ligand played a key role in stabilizing transition states during dehydrogenation steps.This work identified the roles of vital ligand components to boost catalytic performance and offered rationales for designing metal-ligand cooperative nonprecious metal complexes.

关键词： acceptorless alcohol dehydrogenation η^(5)-C_(5)Me_(5)-Co metal-ligand cooperation theoretical calculation

A flexible solid polymer electrolyte enabled with lithiated zeolite for high performance lithium battery

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Nano Research 2023年第7期16卷 9443-9452页

作者： Zhiyu Ding Qiming Tang Qi Zhang Penghui Yao Xingjun Liu Junwei Wu Shenzhen Key Laboratory of Advanced Materials Department of Materials Science and EngineeringHarbin Institute of Technology(Shenzhen)Shenzhen 518055China Maryland Energy Innovation Institute University of MarylandCollege ParkMD 20742USA Department of Chemical and Metallurgical Engineering Aalto UniversityKemistintie 1Aalto FI-00076Finland

Solid-state lithium batteries using composite polymer electrolytes(CPEs)have attracted much attention owing to their higher safety compared to liquid electrolytes and flexibility compared to ceramic electrolytes.However,their unsatisfactory lithium-ion conductivity still limits their development.Herein,a high ion conductive CPE with multiple continuous lithium pathways is designed.This new electrolyte consists of poly(vinylidene fluorideco-hexafluoropropylene)(PVDF-HFP)and lithiated X type zeolite(Li-X),which possesses a high ionic conductivity(1.98×10^(-4)S/cm),high lithium transference number(t_(Li^(+))=0.55),wide electrochemical window(4.7 V),and excellent stability against the lithium anode.Density functional theory(DFT)calculation confirms that the Lewis acid sites in zeolite can graft with N,N-dimethylformamide(DMF)and PVDF-HFP chains,resulting in decreased crystallinity of polymer and providing rapid Li+transmission channels.When used in a full cell,the solid Li|Li-X-3%|LiFePO_(4) cell displays excellent cycling stability and rate performance at room temperature and 60℃.Furthermore,pouch cells with the Li-X-3%electrolyte exhibit brilliant safety under extreme conditions,such as folding and cutting.Thus,this proposed zeolite-PVDF-HFP CPE represents a promising potential in the application of making a safer,higher performing,and flexible solid-state lithium battery.

关键词： solid-state lithium batteries composite polymer electrolytes zeolite poly(vinylidene fluorideco-hexafluoropropylene)(PVDF-HFP) flexible

Advances on Na-K liquid alloy-based batteries

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Journal of Energy Chemistry 2022年第8期31卷 313-323,I0009页

作者： Junwei Wu Zhuang Xue Lixuan Yuan Jilei Ye Qinghong Huang Lijun Fu Yuping wu State Key Laboratory of Materials-Oriented Chemical Engineering College of Energy Science and EngineeringNanjing Tech UniversityNanjing 211816JiangsuChina

Sodium-potassium(Na^(-)K)liquid alloys attract increasing research attention,as an ideal alternative of Li metal for metal-based batteries,attributing to their high abundance,low redox potential,high capacity,and dendrite-free properties.In addition,the liquid and self-healing features of Na^(-)K alloys endow good electrode/electrolyte interfacial contact.The recent advances on the Na^(-)K liquid alloy-based batteries(NKBs)are reviewed herein.The anode designs for immobilization of the liquid alloy are introduced.The influences of the electrolyte and cathode materials on the battery performances are discussed.In addition,considering the co-existence of both K^(+)and Na^(+)in the electrolyte,the working mechanisms of the NKBs are elaborated.We also show that despite the improvement,challenges of the NKBs remain.The compatibility between Na^(-)K liquid alloy and electrolyte,as well as disputed working mechanisms,request detailed surface analyses of the liquid alloy and local element distribution evolution in the battery.This review would shed light on the fundamental understanding of Na^(-)K alloy electrochemistry and the development of dendrite-free metal-based energy storage systems with high energy density.

关键词： Sodium-potassium alloy Liquid anode Metal battery Dendrite-free Mechanism

Recent Development of SOFC Metallic Interconnect

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Journal of Materials Science & Technology 2010年第4期26卷 293-305页

作者： Junwei Wu Mechanical & Aerospace Engineering Department West Virginia University Morgantown WV 26506 US National Energy Technology Laboratory Morgantown WV 26507 US Department of Materials Science and Engineering Shenzhen Graduate School Harbin Institute of Technology University Town XiLi Shenzhen 518055 China

Interest in solid oxide fuel cells （SOFC） stems from their higher efficiencies and lower levels of emitted pollutants, compared to traditional power production methods. Interconnects are a critical part in SOFC stacks, which connect cells in series electrically, and also separate air or oxygen at the cathode side from fuel at the anode side. Therefore, the requirements of interconnects are the most demanding, i.e., to maintain high electrical conductivity, good stability in both reducing and oxidizing atmospheres, and close coefficient of thermal expansion （CTE） match and good compatibility with other SOFC ceramic components. The paper reviewed the interconnect materials, and coatings for metallic interconnect materials.

关键词： Solid oxide fuel cells （SOFC） Interconnect Spinel Coating

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Recent advances in modification strategies of silicon-based lithiumion batteries

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Nano Research 2023年第3期16卷 3781-3803页

作者： Wenlei Wang Yu Wang Lixuan Yuan Chaolin You Junwei Wu Lili Liu Jilei Ye Yunling wu Lijun Fu State Key Laboratory of Materials-Oriented Chemical Engineering School of Energy Science and EngineeringNanjing Tech UniversityNanjing 211816China

As potential alternatives to graphite,silicon(Si)and silicon oxides(SiO_(x))received a lot of attention as anode materials for lithiumion batteries owing to their relatively low working potentials,high theoretical specific capacities,and abundant resources.However,the commercialization of Si-based anodes is greatly hindered by their massive volume expansion,low conductivity,unstable solid electrolyte interface(SEI),and low initial Coulombic efficiency(ICE).Continuous endeavors have been devoted to overcoming these challenges to achieve practical usage.This review is centered on the major challenges and latest developments in the modification strategies of Si-based anodes,including structure optimization,surface/interface regulation,novel binders,and innovative design of electrolyte.Finally,outlooks and perspectives of Si-based anodes for future development are presented.

关键词： lithium-ion batteries silicon silicon oxides modification strategies

Realizing complex beams via amplitude-phase digital coding metasurfaces and semidefinite relaxation optimization

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Frontiers of Information Technology & Electronic Engineering 2023年第12期24卷 1708-1716页

作者： Junwei Wu Qiong HUA Hui XU Hanqing YANG Zhengxing WANG Qiang CHENG Tie Jun CUI State Key Laboratory of Millimeter Waves Southeast UniversityNanjing210096China Peng Cheng Laboratory Shenzhen518055China Pazhou Laboratory(Huangpu) Guangzhou510555China

Complex beams play important roles in wireless communications,radar,and satellites,and have attracted great interest in recent years.In light of this background,we present a fast and efficient approach to realize complex beams by using semidefinite relaxation(SDR)optimization and amplitude-phase digital coding metasurfaces.As the application examples of this approach,complex beam patterns with cosecant,flat-top,and double shapes are designed and verified using full-wave simulations and experimental measurements.The results show excellent main lobes and low-level side lobes and demonstrate the effectiveness of the approach.Compared with previous works,this approach can solve the complex beam-forming problem more rapidly and effectively.Therefore,the approach will be of great significance in the design of beam-forming systems in wireless applications.

关键词： Antenna beams Amplitude-phase coding metasurface Far-field synthesis Semidefinite relaxation

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Code recommendation for Android development:how does it work and what can be improved?

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Science China(Information Sciences) 2017年第9期60卷 149-162页

作者： Junwei Wu Liwei SHEN wunan GUO Wenyun ZHAO School of Computer Science Fudan University Shanghai Key Laboratory of Data Science Fudan University

Android applications are developed based on framework and are always pattern-based. For Android developers, they can be facilitated by code recommendation to ensure high development efficiency and quality.Existing research work has proposed several methods and tools to support recommendation in diverse ways.However, how code recommendation work in Android development and what can be further improved to better support Android development has not been clarified. To understand the reality, we conduct a qualitative review on current code recommendation techniques and tools reported in prime literature. The collected work is first grouped into three categories based on a multidimensional framework. Then the review is performed to draw a comprehensive image of the adoption of recommendation in Android development when meeting specific development requirements. Based on the review, we give out possible improvements of code recommendation from two aspects. First, a set of improvement suggestions are presented to enhance the ability of the state-ofthe-art code recommendation techniques. Second, a customizable tool framework is proposed to facilitate the design of code recommendation tools and the tool framework is able to integrate the recommendation features more easily.

关键词： Android code recommendation code search code suggestion code completion code generation

Resistive switching and artificial synaptic performances of memristor based on low-dimensional bismuth halide perovskites

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Nano Research 2023年第7期16卷 10108-10119页

作者： Feifei Luo Yanzhao wu junwei Tong Fubo Tian Xianmin Zhang Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China Department of Physics Freie Universität Berlin14195 BerlinGermany State Key Laboratory of Superhard Materials College of PhysicsJilin UniversityChangchun 130012China

Zero-dimensional(0D)-Cs_(3)Bi_(2)I_(9),two-dimensional(2D)-Cs_(3)Bi_(2)Br_(9),and one-dimensional(1D)-Cs3Bi2Cl9 perovskite films have been successfully grown on indium tin oxide(ITO)glass substrates,which were used to fabricate memristors with the structure of Al/Cs_(3)Bi_(2)X_(9)(X=I,Br,and Cl)/ITO glass.The current three types of memristors exhibited bipolar resistive switching behaviors.Both the endurance and retention time tests clearly demonstrated the excellent stability of present devices.Especially,the ON/OFF ratio of the 0D-Cs_(3)Bi_(2)I_(9)device is close to 104 at the reading voltage of 0.1 V,which is nearly 100 and 1000 times larger than those of the 1D-Cs3Bi2Cl9 device and the 2D-Cs_(3)Bi_(2)Br_(9)device,respectively.The activation energy of halide vacancies in the Cs_(3)Bi_(2)X_(9)(X=I,Br,and Cl)films was calculated using the density functional theory by considering a minimum migration path,demonstrating the dimensionality of the Cs_(3)Bi_(2)X_(9)(X=I,Br,and Cl)film affected the formation and rupture of conductive filaments.Moreover,the short-term plasticity and long-term plasticity of biological synapse were simulated by evaluating the conductance responses of Al/Cs_(3)Bi_(2)X_(9)(X=I,Br,and Cl)/ITO devices under various voltage pulses in detail.The duration time of long-term plasticity in all the present devices can last for up to 250 s.The 0D-Cs_(3)Bi_(2)I_(9)device showed both the highest spikeduration-dependent plasticity and paired-pulse facilitation indexes compared to the other two devices.Additionally,the 0DCs_(3)Bi_(2)I_(9)device successfully established the associative learning behavior by simulating the Pavlov’s dog experiment.

关键词： perovskite films low-dimension resistive switching artificial synapse