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Hierarchical utilization of raw Ti_(3)C_(2)T_(x) MXene for fast preparation of various Ti_(3)C_(2)T_(x) MXene derivatives

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Nano Research 2022年第3期15卷 2746-2755页

作者： Shunlong Zhang Hangjun Ying Pengfei Huang Tiantian Yang wei-qiang Han School of Materials Science and Engineering Zhejiang UniversityHangzhou 310027China

Due to easy re-stacking,low yield of few-layered MXenes(f-MXenes),the applications of MXenes are mainly restricted in multi-layered MXenes(m-MXenes)*** f-MXenes can be prepared from m-MXenes,after exfoliation process,a mass of sediments which are still essentially compact MXenes are usually directly discarded,leading to low utilization of raw ***,a classified preparation strategy is adopted to exploit the raw m-MXenes and traditional MXenes sediments,taking multi-layered Ti_(3)C_(2)T_(x)MXene as an *** rational delamination and subsequent treatment to Ti_(3)C_(2)T_(x)sediments,we succeed in achieving classified and large-scale preparation of various Ti_(3)C_(2)T_(x)MXene derivatives,including few-layered Ti_(3)C_(2)T_(x)(f-Ti_(3)C_(2)T_(x))powders,f-Ti_(3)C_(2)T_(x)films,and Ti_(3)C_(2)T_(x)MXene-derived nanowires with heterostructure of potassium titanate and Ti_(3)C_(2)T_(x).We demonstrate the necessity of“step-by-step delamination”towards traditional Ti_(3)C_(2)T_(x)sediments to improve the yield of f-Ti_(3)C_(2)T_(x)from 15%to 72%;the feasibility of“solution-phase flocculation(SPF)”to fundamentally solve the re-stacking phenomenon,and oxidation degradation issues of f-Ti_(3)C_(2)T_(x)during storage;as well as the convenience of SPF to deal with time-consuming issues of fabricating Ti_(3)C_(2)T_(x)***’s more,alkali-heat treatment of final Ti_(3)C_(2)T_(x)sediments turns waste into treasure of Ti_(3)C_(2)T_(x)-derived nanowires,leading to 100%utilization of raw Ti_(3)C_(2)T_(x).The content of one-dimensional(1D)nanowires in the hybrids can be adjusted by controlling alkalization *** 3D architecture heterostructure composed of 1D nanowires and 2D nanosheets exhibits gorgeous application *** work can expand preparation and application of various MXenes derivatives,promoting process of various MXenes.

关键词： MXenes MXenes derivatives Ti_(3)C_(2)T_(x) step-by-step delamination solution-phase flocculation Alkali-heat treatment

The impacts of evaluation indices and normalization methods on E-TOPSIS optimization of return vent height for an impinging jet ventilation system

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Building Simulation 2022年第12期15卷 2081-2095页

作者： Chao Qin Shi-Hai Wu Hong-qiang Fang wei-Zhen Lu Department of Architecture and Civil Engineering City University of Hong KongHong KongChina School of Architecture and Art Central South UniversityChangshaChina

Stratified air distribution(STRAD)systems have been intensively investigated in recent decades for their energy-saving potential and good indoor air quality ***,the evaluation indices used to optimize STRAD systems and the normalization methods for weight calculation vary from one research to *** study aims to investigate the impacts of evaluation indices on the optimal return vent height of a room cooled by an impinging jet ventilation system(one type of STRAD system).The effects of several widely used normalization methods(i.e.,vector normalization,sum normalization,min-max normalization,and no normalization)on indices weights are *** evaluation indices are cooling coil load(Q_(coil)),energy-saving potential(ΔQ_(coil)),mean age of air(MAA),CO_(2) mass fraction,temperature difference between the head and ankles(ΔT_(0.1-1.1)),predicted mean vote(PMV),predicted percentage of dissatisfied(PPD),and draft rate(DR).The multi-criteria optimization method is the entropy-based technique for order preference by similarity to ideal solution(E-TOPSIS).As a result,the min-max normalization method evens the weight of each index and results in unreasonable relative ***,the raw matrix(i.e.,the normalization is omitted)is suggested for weight *** these indices,ΔT_(0.1-1.1) and PPD play critical ***ΔT_(0.1-1.1),the optimal return vent height changes from mid-level to near-floor,while without PPD,it changes to *** important result is that the Q_(coil) plays the most trivial role,followed by MAA and ***,the optimal return vent height is not determined by energy-saving performance but by performances of thermal comfort.

关键词： evaluation indices normalization method impinging jet ventilation return vent height E-TOPSIS

Density-Functional Theories for Polyelectrolyte Systems

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Chinese Journal of Polymer Science 2024年第9期42卷 1302-1312,I0006页

作者： Jia-wei Zhang Yu-Hang Zhang Bao-Hui Li qiang Wang School of Physics Nankai UniversityTianjin90001China Department of Chemical and Biological Engineering Colorado State University1370 Campus DeliveryFort CollinsCO80523-1370USA

Polymer density-functional theories(PDFTs)have distinct advantages in the study of polyelectrolyte(PE)systems over experiments and molecular *** we give an introductory review of some PDFTs recently developed for PE *** start with a general formalism of PDFTs and its relation to the widely used polymer self-consistent field theory(SCFT),then explain the various correlations that are neglected in SCFT but can be accounted for in PDFTs,including those due to the excluded-volume interaction and chain connectivity of uncharged polymers,the electrostatic correlations of small ions,and the chain correlations in *** also list some applications of PDFTs for PE systems,and finally give some perspectives on future *** hope that our review can attract more researchers to apply and further develop PDFTs as a promising class of theoretical and computational tools.

关键词： Polymer density-functional theories Polyelectrolytes Correlations

Effects of Ni, Cr and W on the microstructural stability of multicomponent CoNi-base superalloys studied using CALPHAD and diffusion-multiple approaches

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Journal of Materials Science & Technology 2021年第21期80卷 139-149页

作者： Wendao Li Longfei Li Changdong wei Ji-Cheng Zhao qiang Feng Beijing Advanced Innovation Center for Materials Genome Engineering State Key Laboratory for Advanced Metals and MaterialsUniversity of Science and Technology BeijingBeijing100083China Department of Materials Science&Engineering The Ohio State UniversityColumbusOH43210USA Department of Materials Science and Engineering University of MarylandCollege ParkMD20742USA

The alloying effects of Ni,W and Cron the microstructural stability of CoNi-base alloys were investigated using a multicomponent diffusion multiple after being aged at 1000℃ for 1000 *** diffusion multiple was carefully designed based on thermodynamic *** relationships between alloy compositions and microstructural characteristics were established over a large compositional range using this single sample,and the alloying effects of Ni,W and Cron the elemental partitioning behaviors betweenγ and γ' two phases were thermodynamically analyzed using high-throughput *** results together show that an increase of Ni content increases the γ' volume faction in the long-term aged ***,the higher Ni content leads to the precipitation of the χ phase by promoting the partitioning of W from the γ' phase to the γ *** decrease of W content dramatically reduces theγ' volume faction,but the addition of Cr can properly counteract this effect by promoting the partitioning of Al and Ti from the γ phase to the γ' *** study will be helpful for accelerating the development of novel γ'-strengthened multicomponent CoNi-base alloys,as well as providing experimental data to improve the thermodynamic database.

关键词： CoNi-base superalloys Microstructural stability Diffusion-multiple CAHPHAD Partitioning behavior

Partial Atomic Tin Nanocomplex Pillared Few-Layered Ti_(3)C_(2)Tx MXenes for Superior Lithium-Ion Storage

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Nano-Micro Letters 2020年第6期12卷 176-189页

作者： Shunlong Zhang Hangjun Ying Bin Yuan Renzong Hu wei-qiang Han School of Materials Science and Engineering Zhejiang University310027 HangzhouPeople’s Republic of China School of Materials Science and Engineering South China University of Technology510641 GuangzhouPeople’s Republic of China Key Laboratory of Advanced Energy Storage Materials of Guangdong Province 510641 GuangzhouPeople’s Republic of China

MXenes have attracted great interest in various fields,and pillared MXenes open a new path with larger interlayer ***,the further study of pillared MXenes is blocked at multilayered state due to serious restacking phenomenon of few-layered MXene *** this work,for the first time,we designed a facile NH4+method to fundamentally solve the restacking issues of MXene nanosheets and succeeded in achieving pillared few-layered *** nanocomplex pillared few-layered Ti3C2Tx(STCT)composites were synthesized by introducing atomic Sn nanocomplex into interlayer of pillared few-layered Ti3C2Tx MXenes via pillaring *** MXene matrix can inhibit Sn nanocomplex particles agglomeration and serve as conductive ***,the Sn nanocomplex particles can further open the interlayer spacing of Ti3C2Tx during lithiation/delithiation processes and therefore generate extra *** from the“pillar effect,”the STCT composites can maintain 1016 mAh g^?1 after 1200 cycles at 2000 mA g^?1 and deliver a stable capacity of 680 mAh g^?1 at 5 A g^?1,showing one of the best performances among MXene-based *** work will provide a new way for the development of pillared MXenes and their energy storage due to significant breakthrough from multilayered state to few-layered one.

关键词： Pillared MXene Few-layered MXene Tin nanocomplex Lithium-ion storage

Overview of Graphene as Anode in Lithium-Ion Batteries

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Journal of Electronic Science and Technology 2018年第1期16卷 57-68页

作者： Ri-Peng Luo wei-qiang Lyu Ke-Chun Wen wei-Dong He School of Energy Science and Engineering University of Electronic Science and Technology of ChinaChengdu 611731

Graphene, as a fabulously new-emerging carbonaceous material with an ideal two-dimensional rigid honeycomb structure, has drawn extensive attention in the field of material science due to extraordinary properties, including mechanical robustness, large specific surface area, desirable flexibility, and high electronic conductivity. In particular,as an auxiliary material of electrode materials, it has the potential to improve the performance of lithium-ion batteries. However, wide utilization of graphene in lithium-ion batteries is not implemented since tremendous challenges and issues,such as quality,quantity, and cost concerns, hinder its *** remains a debate whether graphene can act as an impetus in the evolution of lithium-ion batteries. In this review, we summarize the desirable properties, several common synthesis methods as well as applications of graphene as the anode in lithium-ion batteries, seeking to provide insightful guidelines for further development of graphene-based lithium-ion batteries.

关键词： Applications electrical properties graphene lithium-ion battery

Impacts of land disturbance and restoration on runoff production and sediment yield in the Chinese Loess Plateau

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Journal of Arid Land 2017年第1期9卷 76-86页

作者： AI Ning wei Tianxing ZHU Qingke qiang Fangfang MA Huan QIN wei School of Soil and Water Conservation Beijing Forestry UniversityBeijing 100083China College of Life Science Yan'an UniversityYan'an 716000China China Institute of Water Resources and Hydropower Research Beijing 100048China International Research and Training Center on Erosion and Sedimentation Beijing 100048China

Land disturbance and land restoration are important factors influencing runoff production and sediment yield in the semi-arid loess regions of China. This study compared the runoff production and sediment yield during the early stage after land disturbance（ESLD） with those during restoring stage after land disturbance（RSLD）. Grey relational analysis was used to analyse the importance of each one of the influencing factors（vegetation, rainfall, soil and topography） in affecting the runoff production and sediment yield. Our results showed that during ESLD, topography was the most critical factor controlling the runoff production, while soil was the most important factor controlling the sediment yield. During RSLD, vegetation was more important in affecting runoff production, while rainfall was more important in affecting sediment yield. In additional, this study demonstrated that both the runoff production and the sediment yield can be effectively reduced by restoring vegetation on severely-disturbed lands, thus providing an important theoretical basis for better implementations of the Grain for Green Program. Our results revealed that the vegetation types of Hippophae rhamnoides＋Pinus tabulaeformis and H. rhamnoides are better plant selections for land restoration in this area, especially for relatively gentle slopes（i.e., less than 20 degrees）.

关键词： land disturbance/ restoration grey relational analysis runoff sediment yield Loess Plateau

A field investigation into the characteristics and formation mechanisms of particles during the operation of laser printers and photocopiers

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Journal of Environmental Sciences 2023年第4期126卷 697-707页

作者： qiang Wang Daizhi An Zhengquan Yuan Rubao Sun wei Lu Lili Wang Chinese People’s Liberation Army Center for Disease Control and Prevention Beijing 100071China

Indoor particle release from toner printing equipment (TPE) is a major health concern and has received wide *** this study,nine printing centers were randomly selected and three working phases were simulated,namely,non-working,normal printing/copying,and heavy printing/*** dynamics of the ozone (O_(3)),volatile organic compound (VOC),and particle emissions from TPE were determined by portable *** showed that particles,VOCs,and O_(3)were indeed discharged,and particles and VOCs concentrations remained at high *** them,44%of the rooms represented high-level particle ***-sized particles,especially nanoparticles,were positively correlated with VOCs,but were inversely proportional to the O_(3)*** elements,Ca,Al,Mg and Ni,were usually present in nanoparticles because of the discharge of ***,Al,K,Ni and Pb were found in the submicrometer-sized particles and were consistent with the toner *** potential particle precursors were identified,which suggested that styrene was the most likely secondary organic aerosol (SOA) ***,the use of the toner formulation and the discharge of paper attribute to the TPE-emitted particles,in which styrene is a specific monitoring indicator for the formation of SOA.

关键词： Toner-based printing equipment Particulate matter Ozone Volatile organic compound Secondary organic aerosol precursor

A Dual-Band Coaxial Waveguide Mode Converter for High-Power Microwave Applications

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Chinese Physics Letters 2011年第6期28卷 326-328页

作者： ZHANG qiang YUAN Cheng-wei LIU Lie Lab 206 College of Optoelectronic Science and EngineeringNational University of Defense TechnologyChangsha 410073

A dual-band coaxial waveguide mode converter is *** the converter,the TEM mode(***)and TM01 circular waveguide(***01)mode are transformed simultaneously into TE11 coaxial waveguide(***11)mode and TE11 circular waveguide(***11)mode,*** optimized geometrical dimensions are achieved by employing the mode coupling theory.A mode converter at 1.3 GHz and 5.0 GHz is designed,and conversion efficiencies of ***−***11 and ***01−***11 are 99.88%and 99.70%at central frequency,*** the frequency ranges 1.15–1.51 GHz and 4.87–5.19 GHz,the conversion efficiency exceeds 90%.A good agreement between theoretical calculations and computer simulations is observed,demonstrating the feasibility of the dual-band mode converter.

关键词： waveguide coaxial Converter