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Gas-phase synthesis of Ti_(2)CCl_(2) enables an efficient catalyst for lithiumsulfur batteries

The Innovation 2024年第1期5卷 33-40页

作者： Maoqiao Xiang Zihan Shen Jie Zheng Miao Song Qiya He Yafeng Yang Jiuyi Zhu Yuqi Geng Fen Yue Qinghua Dong Yu Ge Rui Wang jiake wei weiliang Wang Haiming Huang Huigang Zhang Qingshan Zhu Chuanfang John Zhang State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China School of Chemical Engineering University of the Chinese Academy of SciencesBeijing 100049China Innovation Academy for Green Manufacture Chinese Academy of SciencesBeijing 100190China China Nuclear Power Engineering Co. Ltd.117 West Third Ring RoadNorth SectionBeijing 100840China College of Materials Science&Engineering Sichuan UniversityChengdu 610065China State Key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China School of Physics Guangdong Province Key Laboratory of Display Material and TechnologyCenter for Neutron Science and TechnologySun Yat-sen UniversityGuangzhou 510275China Solid State Physics&Material Research Laboratory School of Physics and Materials ScienceGuangzhou UniversityGuangzhou 510006China

MXenes have aroused intensive enthusiasm because of their exotic properties and promising ***,to date,they are usually synthesized by etching *** synthetic technologies provides more opportunities for innovation and may extend unexplored ***,we report a bottom-up gas-phase synthesis of Cl-terminated MXene(Ti_(2)CCl_(2)).The gas-phase synthesis endows Ti_(2)CCl_(2) with unique surface chemistry,high phase purity,and excellent metallic conductivity,which can be used to accelerate polysulfide conversion kinetics and dramatically prolong the cyclability of Li-S ***-depth mechanistic analysis deciphers the origin of the formation of Ti_(2)CCl_(2) and offers a paradigm for tuning MXene chemical vapor *** brief,the gas-phase synthesis transforms the synthesis of MXenes and unlocks the hardly achieved potentials of MXenes.

关键词： synthesis phase lithium

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In-situ TEM study of the dynamic behavior of the graphene-metal interface evolution under Joule heating

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Science China(Technological Sciences) 2016年第7期59卷 1080-1084页

作者： wei jiake XU Zhi WANG Hao WANG WenLong BAI XueDong Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China International Center for Quantum Materials and School of Physics Peking University Beijing 100871 China Collaborative Innovatton Center of Quantum Matter Beijing 100871 China

The dynamic behavior of the interface between few layer graphene(FLG) and tungsten metal tips under Joule heating has been studied by in-situ transmission electron microscopy(TEM) method. High-resolution and real-time observations show the tungsten tip ‘swallow' carbon atoms of the FLG and ‘spit' graphite shells at its surface. The tip was carbonized to tungsten carbide(WC, W_2 C and WC_x) after this process. A carbon diffusion mechanism has been proposed based on the diffusion of carbon atoms through the tungsten tip and separation from the surface of the tip. After Joule heating, the initial FLG-metal mechanical contact was transformed to FLG-WCx-W contact, which results in significant improvement on electrical conductivity at the interface.

关键词： In-situ TEM graphene-metal contact Joule heating carbon atoms diffusion

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3D graphene foam-supported cobalt phosphate and borate electrocatalysts for high-efficiency water oxidation

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Science Bulletin 2015年第16期60卷 1426-1433页

作者： Min Zeng Hao Wang Chong Zhao jiake wei Wenlong Wang Xuedong Bai Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences

The cobalt phosphate-/cobalt borate-based oxygen-evolving catalysts （OECs） are the important class of earth-abundant electrocatalysts that can operate with high activity for water splitting under benign conditions. This article reports the integration of cobalt phosphate （Co- Pi） and cobalt borate （Co-Bi） OECs with three-dimensional （3D） graphene foam （GF） for the electrocatalytic water oxidation reaction. The GF showed a unique advantage to serve as a highly conductive 3D support with large capacity for anchoring and loading Co-OECs, thereby facilitating mass and charge transfer due to the large amount of active sites provided by the 3D graphene scaffold. As a result, this integrated system of GF and Co-OECs exhibits synergistically enhanced catalytic activity. The overpotential （η） of Co-Pi and Co-Bi/graphene catalysts is about 0.390 and 0.315 V in neutral solutions, respectively. Besides, the integrated Co-OECs/graphene catalysts have also exhibited improved and stable oxygen evolution catalytic ability in alkaline solution.

关键词： Water splitting Oxygen evolutioncatalyst Cobalt phosphate and borate Graphene foam

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Electrochemical solid-state amorphization in the immiscible Cu-Li system

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Science Bulletin 2018年第18期63卷 1208-1214页

作者： Muhua Sun jiake wei Zhi Xu Qianming Huang Yu Zhao Wenlong Wang Xuedong Bai Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences School of Physical Sciences University of Chinese Academy of Sciences

As a typical immiscible binary system, copper (Cu) and lithium (Li) show no alloying and chemical intermixing under normal circumstances. Here we show that, when decreasing Cu nanoparticle sizes into ultrasmall range, the nanoscale size effect can play a subtle yet critical role in mediating the chemical activity of Cu and therefore its miscibility with Li, such that the electrochemical alloying and solidstate amorphization will occur in such an immiscible system. This unusual observation was accomplished by performing in-situ studies of the electrochemical lithiation processes of individual CuO nanowires inside a transmission electron microscopy (TEM). Upon lithiation, CuO nanowires are first electrochemically reduced to form discrete ultrasmall Cu nanocrystals that, unexpectedly, can in turn undergo further electrochemical lithiation to form amorphous Cu Lixnanoalloys. Real-time TEM imaging unveils that there is a critical grain size (ca. 6 nm), below which the nanocrystalline Cu particles can be continuously lithiated and amorphized. The possibility that the observed solid-state amorphization of Cu-Li might be induced by electron beam irradiation effect can be explicitly ruled out; on the contrary, it was found that electron beam irradiation will lead to the dealloying of as-formed amorphous Cu Lixnanoalloys.

关键词： Immiscible Cu-Li system Electrochemical solid-state amorphization Nanoscale size effect In-situ TEM Lithium ion battery

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Filament growth dynamics in solid electrolyte-based resistive memories revealed by in situ TEM

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Nano Research 2014年第7期7卷 1065-1072页

作者： Xuezeng Tian Lifen Wang jiake wei Shize Yang Wenlong Wang Zhi Xu Xuedong Bai Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 7 O0190 China

Solid electrolyte based-resistive memories have been considered to be a potential candidate for future information technology with applications in non-volatile memory, logic circuits and neuromorphic computing. A conductive filament model has been generally accepted to be the underlying mechanism for the resistive switching. However, the growth dynamics of such conductive filaments is still not fully understood. Here, we explore the controllability of filament growth by correlating observations of the filament growth with the electric field distribution and several other factors. The filament growth behavior has been recorded using in situ transmission electron microscopy. By studying the real- time recorded filament growth behavior and morphologies, we have been able to simulate the electric field distribution in accordance with our observations. Other factors have also been shown to affect the filament growth, such as Joule heating and electrolyte infrastructure. This work provides insight into the controllable growth of conductive filaments and will help guide research into further functionalities of nanoionic resistive memories.

关键词： resistive switching conductive filaments in situ transmissionelectron microscope real-time observation computer simulation

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Real-time in situ TEM studying the fading mechanism of tin dioxide nanowire electrodes in lithium ion batteries

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Science China(Technological Sciences) 2013年第11期56卷 2630-2635页

作者： WANG LiFen XU Zhi YANG ShiZe TIAN XueZeng wei jiake WANG WenLong BAI XueDong Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of Sciences

Fading mechanism of tin dioxide （SnO2） electrodes in lithium ion batteries has attracted much attentions, which is of great importance for the battery applications. In this paper, electrochemical lithiation-delithiation cycles of individual SnO2 nanowires were conducted in situ in a high-resolution transmission electron microscopy （TEM）. Major changes in volume with expan- sions of 170%~300% on SnO2 nanowire electrodes were observed during the first lithiation process in electrochemical cycling, including conversion reaction of SnO2 precursor to Li20 matrix and active lithium host Sn, and alloying of Sn with Li to form brittle Li-Sn alloy. SnO2 nanowire electrodes were inclined to suffer from thermal runaway condition in the first two cycles. During cycling, morphology and composition evolution of SnO2 nanowire electrodes were recorded. Cyclic lithiation and del- ithiation of the electrode demonstrated the phase transition between Lii3Sn5 and Sn. Metallic Sn clusters were formed and their sizes enlarged with increasing cycle times. Detrimental aggregation of Sn clusters caused pulverization in SnO2 nanowire elec- trodes, which broke the conduction and transport path for electrons and lithium ions. The real-time in situ TEM revealed fading mechanism provides important guidelines for the viable design of the SnO2 nanowire electrodes in lithium ion batteries.

关键词： lithium ion battery tin dioxide nanowire electrode fading mechanism tin aggregation in situ TEM

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Towards the controlled CVD growth of graphitic B-C-N atomic layer films： The key role of B-C delivery molecular precursor

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Nano Research 2016年第5期9卷 1221-1235页

作者： Hao Wang Chong Zhao Lei Liu Zhi Xu jiake wei Wenlong Wang Xuedong Bai Enge Wang In ternational Center for Quantum Materials School of Physics Peking University Beijing 100871 China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China Collaborative Innovation Center of Quantum Matter Beijing 100871 China

Graphene-like, ternary system B-C-N atomic layer materials promise highly tunable electronic properties and a plethora of potential applications. However, thus far, experimental synthesis of the B-C-N atomic layers normally yields a microscopic phase-segregated structure consisting of pure C and BN domains. Further, growing the truly ternary B-C-N phase layers with homogenous atomic arrangements has proven to be very challenging. Here, in designing a better- controlled process for the chemical vapor deposition （CVD） growth of B-C-N atomic layer films with the minimized C and BN phase segregation, we selected trimethyl borane （TMB）, a gaseous organoboron compound with pre-existing B--C bonds, as the molecular precursor to react with ammonia （NH3） gas that serves as the nitrification agent. The use of this unique B-C delivery precursor allows for the successful synthesis of high-quality and large-area B-C-N atomic layer films. Moreover, the TMB/NH3 reactant combination can offer a high level of tunability and control of the overall chemical composition of B-C-N atomic layers by regulating the relative partial pressure of two gaseous reactants. Electrical transport measurements show that a finite energy gap can be opened in the as-grown B-C-N atomic layers and its tunability is essentially dependent on the relative C to BN atomic compositions. On the basis of carefully controlled experiments, we show that the pre-existing B-C bonds in the TMB molecular precursor have played a crucial role in effectively reducing the C and BN phase segregation problem, thereby facilitating the formation of truly ternary B-C-N phase atomic layers.

关键词： graphitic B-C-N atomic layer chemical vapor deposition B-C delivery precursor minimized phase segregation

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Recent development of studies on the mechanism of resistive memories in several metal oxides

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Science China(Physics,Mechanics & Astronomy) 2013年第12期56卷 2361-2369页

作者： TIAN XueZeng WANG LiFen LI XiaoMin wei jiake YANG ShiZe XU Zhi WANG WenLong BAI XueDong Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of Sciences

Resistive switching random access memories(RRAM)have been considered to be promising for future information technology with applications for non-volatile memory,logic circuits and neuromorphic *** performances of those resistive devices are approaching the realistic levels for *** this paper,we review the progress of valence change type memories,including relevant work reported by our *** electrode engineering and in-situ transmission electron microscopy(TEM)high-resolution observation have been implemented to reveal the influence of migration of oxygen anions/vacancies on the resistive switching *** understanding of resistive memory mechanism is significantly important for device applications.

关键词： resistive switching effect valence change memory electrode engineering in-situ TEM

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江苏利用科技催生文化新业态的机理与路径

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江苏科技信息 2015年第5期32卷 4-6页

作者：魏加科江苏经贸职业技术学院公共管理学院江苏南京210000

发展新兴文化业态是助推文化产业成为国民经济支柱产业的核心力量。科技创新是创新文化业态的源泉,促进高新技术与文化深度融合,发展新文化业态,是江苏转变经济发展方式,推动产业结构转型升级的战略利器,也是建成文化强省的重要途径。... 详细信息

发展新兴文化业态是助推文化产业成为国民经济支柱产业的核心力量。科技创新是创新文化业态的源泉,促进高新技术与文化深度融合,发展新文化业态,是江苏转变经济发展方式,推动产业结构转型升级的战略利器,也是建成文化强省的重要途径。文章分析了新兴文化业态的特点,探讨江苏利用科技催生文化新业态的内在机理和实现路径,并且提出具体举措,为江苏文化新业态发展提供对策和参考。

关键词：科技文化新业态文化产业实现路径机理

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矩镰荚苜蓿越冬期地下芽的组织化学特征与分化规律

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草业科学 2022年第2期39卷 300-308页

作者：杨小霞魏甲科夏建强方强恩张勃甘肃农业大学草业学院甘肃兰州730070

为了揭示矩镰荚苜蓿(Medicago archiducis-nicolai)地下芽越冬机理,采用石蜡切片法,通过组织化学染色,跟踪观测了该植物在自然越冬过程中地下芽的组织化学特征与分化过程。结果显示:在越冬期,地下芽内淀粉粒主要贮存在芽体皮层、髓部、... 详细信息

为了揭示矩镰荚苜蓿(Medicago archiducis-nicolai)地下芽越冬机理,采用石蜡切片法,通过组织化学染色,跟踪观测了该植物在自然越冬过程中地下芽的组织化学特征与分化过程。结果显示:在越冬期,地下芽内淀粉粒主要贮存在芽体皮层、髓部、芽尖外围幼叶、芽尖基层组织和叶原基底部,蛋白质主要贮存在芽尖生长锥、叶原基顶部和芽体形成层;秋末冷适应期,地下芽芽体快速伸长,芽内淀粉粒开始急速降解,但与其他时期相比,淀粉总含量仍处较高水平;进入初冬期后,随气温的下降,芽分化与伸长生长开始减慢,到隆冬冻胁迫期,芽锥和芽体生长停止,芽内淀粉几乎全部降解;之后随气温回升,芽体开始恢复生长,但芽锥分生生长直至返青期才开始恢复。分析表明,矩镰荚苜蓿越冬期间地下芽生长停滞和芽内淀粉粒含量降低是其休眠态转变的重要标志,休眠芽通过淀粉粒水解代谢,增加细胞可溶性糖浓度、降低细胞冰点是其抵御冬季低温胁迫的适应机制。

关键词：地下芽结构越冬休眠组织化学淀粉粒腋芽青藏高原

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