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Invisible vapor catalysis in graphene growth by chemical vapor deposition

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Nano Research 2024年第5期17卷 4259-4269页

作者： Xiucai sun Xiaoting Liu Zhongti sun Xintong Zhang Yuzhu Wu Yeshu Zhu Yuqing Song Kaicheng Jia Jincan Zhang Luzhao sun Wan-Jian Yin Zhongfan Liu Center for Nanochemistry Beijing Science and Engineering Center for NanocarbonsBeijing National Laboratory for Molecular ScienceCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China Beijing Graphene Institute(BGI) Beijing 100095China Academy for Advanced Interdisciplinary Studies Peking UniversityBeijing 100871China School of Materials Science and engineering Jiangsu UniversityZhenjiang 212013China Department of engineering University of CambridgeCambridge CB30FAUK college of Energy Soochow Institute for Energy and Materials InnovationS(SIEMIS)Jiangsu Provincial Key Laboratory for Advanced Carbon Materials and Wearable Energy TechnologiesSoochow UniversitySuzhou 215006China

Vapor catalysis was recently found to play a crucial role in superclean graphene growth via chemical vapor decomposition(CVD).However,knowledge of vapor-phase catalysis is scarce,and several fundamental issues,including vapor compositions and their impact on graphene growth,are ***,by combining density functional theory(DFT)calculations,an ideal gas model,and a designed experiment,we found that the vapor was mainly composed of Cui clusters with tens of *** vapor pressure was estimated to be~10^(-12)-10^(-1)1 bar under normal low-pressure CVD system(LPCVD)conditions for graphene growth,and the exposed surface area of Cui clusters in the vapor was 22-269 times that of the Cu substrate surface,highlighting the importance of vapor *** calculations show Cu clusters,represented by Cu17,have strong capabilities for adsorption,dehydrogenation,and decomposition of *** exhibit an adsorption lifetime and reaction flux six orders of magnitude higher than those on the Cu surface,thus providing a sufficient supply of active C atoms for rapid graphene growth and improving the surface cleanliness of the synthesized *** experimental validation showed that increasing the amount of Cu vapor improved the as-synthesized graphene growth rate and surface *** study provides a comprehensive understanding of vapor catalysis and the fundamental basis of vapor control for superclean graphene rapid growth.

关键词： vapor catalysis graphene growth chemical vapor deposition first-principles calculation

Interface engineering enabled sintering-resistant metal nanocatalysts via reverse Ostwald ripening

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Science China Chemistry 2024年第9期67卷 2789-2791页

作者： Ying sun Wenhui Fang Jieshan Qiu Institute of Clean Energy Chemistry Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials of Liaoning ProvinceCollege of ChemistryLiaoning UniversityShenyang 110036China State Key Laboratory of Chemical Resource engineering College of Chemical EngineeringBeijing University of Chemical TechnologyBeijing 100029China

The design and fabrication of advanced nanocatalysts with the high activity,selectivity,and superior durability remains a big challenge in industrial catalysis[1,2].The sintering of nanocatalysts under the thermally and/or chemically triggered conditions is a bottle-neck issue,which seriously decreases the amount of the exposed active sites and changes the original electronic structure of catalysts,resulting in the irreversible catalyst deactivation and high capital and time cost in industrial operation[3].

关键词： durability irreversible catalysis

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多因素下迷宫密封泄漏分析及实验验证

清华大学学报（自然科学版） 2024年第8期64卷 1414-1423页

作者：孙巍伟刘跃李永健蒋杰北京信息科技大学机电工程学院北京100192 清华大学机械工程系高端装备界面科学与技术全国重点实验室北京100084 成都市排水有限责任公司物资设备中心成都610039

迷宫密封作为转轴密封的主要形式,被广泛应用于离心式压缩机、航空发动机和膨胀透平机等旋转机械。为提高迷宫密封的密封性能和满足现代旋转机械需求,需要从多角度开展迷宫密封的结构优化研究。该文基于FLUENT软件进行迷宫密封流场仿真... 详细信息

迷宫密封作为转轴密封的主要形式,被广泛应用于离心式压缩机、航空发动机和膨胀透平机等旋转机械。为提高迷宫密封的密封性能和满足现代旋转机械需求,需要从多角度开展迷宫密封的结构优化研究。该文基于FLUENT软件进行迷宫密封流场仿真,采用计算流体动力学(computational fluid dynamics, CFD)方法,分析了迷宫密封几何参数及齿形结构对泄漏量的影响规律;提出了占空比、深宽比2种参数定义,通过调整参数设置,可以消除空腔高度、空腔宽度、齿厚和齿距4种参数间的耦合影响,可为参数优化设计提供重要参考;建立了高转速迷宫密封实验系统,通过实验验证,仿真结果最大误差仅为3%。结果表明:在工况参数中,压差对泄漏量具有显著影响,而转速基本不会影响泄漏量;在几何参数中,密封间隙对泄漏量具有显著影响,而占空比、深宽比和齿距对泄漏量的影响较小;在齿形结构中,斜齿具有更小的泄漏量,并且减小前齿与后齿倾斜角将有益于降低泄漏量。

关键词：迷宫密封占空比深宽比齿形结构泄漏量

Synthesis of multifunctional additives for solid propellants:Structure,properties and mechanism

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Defence Technology（防务技术） 2024年第3期33卷 308-316页

作者： Pingan Zhang Lina sun Jianmin Yuan Jianru Deng college of Chemistry and Chemical engineering Hunan UniversityChangsha 410082PR China college of Material Science and engineering Hunan UniversityChangsha 410082PR China Hu Bei Sanjiang Aerospace Jianghe Chemical Technology Co. LtdYichang 444200PR China

To simplify the composite propellant formulation and address the current issue of the single-functionality present in existing additives,the multi-cyano,amine-based polybutadiene(AEHTPB-CN)was prepared based on AEHTPB by adopting appropriate synthesis *** replacing 10% of HTPB binder in the propellant formulation,it can effectively enhance the interfacial bond strength between the propellant binder matrix and solid fillers(AP(ammonium perchlorate)and RDX(cyclotrimethylene-trinitramine)),the mechanical properties of the HTPB/AP/RDX/Al propellant were superior to blank control propellant with an improvement of 35.4% in tensile strength,62.0% enhancement in elongation at break,and reduce the propellant burn rate by 10.7% with any energy *** function mechanism of AEHTPB-CN was systematically elucidated through experiments and computer simulation *** results show that the tertiary amine group in AEHTPB-CN can react with AP to form ammonium ionic bonds,and the hydroxyl and cyano groups can form hydrogen bonding interactions with AP,which enables AEHTPB-CN to be firmly adsorbed on the AP surface through chemical and physical *** RDX,the interfacial bonding effect of AEHTPB-CN is attributed to their ability to form C-H···N≡C weak hydrogen bonding interaction between the cyano group and RDX methylene group.

关键词： Hydroxyl-terminated polybutadiene(HTPB) HTPB propellant Chemical modification Bonding agent Mechanism

Influence of modulation ratio on structure and properties of nanoscale ZrB_2/ZrAlN multilayered coatings

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Science China(Technological Sciences) 2010年第3期53卷 772-775页

作者： LI DeJun 1,KANG YuanBin 1,DONG Lei 1,DENG XiangYun 1,LIU Hao 2 &sun XueLiang 2 1college of Physics and Electronic Information Science,Tianjin Normal University,Tianjin 300387,China 2 Department of mechanical&Materials engineering,University of Western Ontario,London ON,Canada college of Physics and Electronic Information Science Tianjin Normal University

ZrB2/ZrAlN multilayered coatings with various modulation ratios(t ZrB2:t ZrAlN)and constant modulation periods were prepared by magnetron sputtering system at room ***,XRD,surface profiler and nano-indenter were employed to investigate the influences of tZ rB 2:tZrAlNon the microstructure and mechanical properties of the *** interfaces and nanoscale multilayered modulation were confirmed by *** multilayer with modulation period of 40 nm and ratio of 3:1 displayed the highest hardness(36.4 GPa)and critical fracture load(76.477 mN)with lower *** polycrystalline structure and multilayered modulate structure were directly responsible for the enhanced mechanical properties.

关键词： ZrB2/ZrAlN multilayered coating magnetron sputtering modulation ratio nanoscale

Imide-based covalent organic framework with excellent cyclability as an anode material for lithium-ion battery

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Chinese Chemical Letters 2024年第6期35卷 206-210页

作者： Yue Qian Zhoujia Liu Haixin Song Ruize Yin Hanni Yang Siyang Li weiwei Xiong Saisai Yuan Junhao Zhang Huan Pang School of Environmental&Chemical engineering Jiangsu University of Science and TechnologyZhenjiang 212003China School of Chemistry&Chemical engineering Yangzhou UniversityYangzhou 225009China Shandong Key Laboratory of Biochemical Analysis College of Chemistry and Molecular EngineeringQingdao University of Science and TechnologyQingdao 266042China

Covalent organic frameworks(COFs)exhibiting reversible redox behaviors have been identified as promising candidates for constructing electrode materials in lithium-ion batteries(LIBs).However,their extensive application has been limited due to finite redox sites and poor structural *** this study,we design and synthesize a novel polyimide covalent organic framework(PI-COF)using the traditional solvothermal method and successfully apply it as an anode material for *** large conjugated structure of PI-COF accelerates charge transfer,while its large surface area provides more active sites,making PI-COF an attractive anode material for ***,the PI-COF anode material demonstrates high reversible specific capacity and excellent long-term cycling stability due to its COF ***,the PI-COF electrodes deliver a specific capacity of 800 m Ah/g at a current density of 200 m A/g after 200 cycles,while a specific capacity of 450 m Ah/g at a current density of 1000 m A/g is sustained after 800 *** outstanding lithium storage capacity,particularly the satisfactory long-term cycling stability,establishes PI-COF as a promising material for LIBs.

关键词： Ethylenediaminetetraacetic dianhydride Covalent organic frameworks Polyimide Lithium-ion battery Anode material

Interfacial charge redistribution to promote the catalytic activity of Vs-CoP-CoS_(2)/C n-n heterojunction for oxygen evolution

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Chinese Chemical Letters 2024年第2期35卷 611-616页

作者： Jiawen sun Hui Xue Jing sun Niankun Guo Tianshan Song Yi-Ru Hao Qin Wang college of Chemistry and Chemical engineering Inner Mongolia UniversityHohhot 010021China

Modulating surface charge redistribution based on interface and defect engineering has been considered as a resultful means to boost electrocatalytic ***,the mechanism of synergistic regulation of heterojunction and vacancy defects remains ***,a Vs-CoP-CoS_(2)/C n-n heterojunction with sulfur vacancies is successfully constructed,which manifests superior electrocatalytic activity for oxygen evolution,as demonstrated by a low overpotential of 170 mV to reach 10 mA/cm^(2).The experimental results and density functional theory calculations testify that the outstanding OER performance of Vs-CoP-CoS_(2)/C heterojunction is owed to the synergistic effect of sulfur vacancies and built-in electric field at n-n heterogeneous interface,which accelerates the electron transfer,induces the charge redistribution,and regulates the adsorption energy of active intermediates during the *** study affords a promising means to regulate the electrocatalytic performance by the construction of heterogeneous interfaces and defects,and in-depth explores the synergistic mechanisms of n-n heterojunction and vacancies.

关键词： Charge redistribution n-n Heterojunction Built-in electric field Sulfur vacancy Oxygen evolution reaction

Dynamic damage and stress-strain relations of ultra-high performance cementitious composites subjected to repeated impact

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Science China(Technological Sciences) 2010年第6期53卷 1520-1525页

作者： LAI JianZhong1 & sun Wei2 1 Department of Materials Science and engineering,Nanjing University of Science and Technology,Nanjing 210094,China 2 college of Materials Science and engineering,Southeast University,Nanjing 211189,China Department of Materials Science and engineering Nanjing University of Science and Technology college of Materials Science and engineering Southeast University

Ultra-high performance cementitious composites (UHPCC) were prepared by replacing 60% of cement with ultra-fine industrial waste *** dynamic damage and compressive stress-strain relations of UHPCC were studied using split Hopkinson pressure bar (SHPB).The damage of UHPCC subjected to repeated impact was measured by the ultrasonic pulse velocity *** show that the dynamic damage of UHPCC increases linearly with impact times and the abilities of repeated impact resistance of UHPCC are improved with increasing fiber volume *** stress waves on impact were recorded and the average stress,strain and strain rate of UHPCC were calculated based on the wave propagation *** effects of strain rate,fibers volume fraction and impact times on the stress-strain relations of UHPCC were *** show that the peak stress and elastic modulus decrease while the strain rate and peak strain increase gradually with increasing impact times.

关键词： ultra-high performance cementitious composites (UHPCC) split Hopkinson pressure bar (SHPB) repeated impact damage stress-strain

Phenotypic Image Recognition of Asparagus Stem Blight Based on Improved YOLOv8

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Computers, Materials & Continua 2024年第9期80卷 4017-4029页

作者： Shunshun Ji Jiajun sun Chao Zhang college of Information Science and engineering Shandong Agricultural UniversityTai’an271000China

Asparagus stem blight,also known as“asparagus cancer”,is a serious plant disease with a regional *** widespread occurrence of the disease has had a negative impact on the yield and quality of asparagus and has become one of the main problems threatening asparagus *** improve the ability to accurately identify and localize phenotypic lesions of stem blight in asparagus and to enhance the accuracy of the test,a YOLOv8-CBAM detection algorithm for asparagus stem blight based on YOLOv8 was *** algorithm aims to achieve rapid detection of phenotypic images of asparagus stem blight and to provide effective assistance in the control of asparagus stem *** enhance the model’s capacity to capture subtle lesion features,the Convolutional Block AttentionModule(CBAM)is added after C2f in the ***,the original CIoU loss function in YOLOv8 was replaced with the Focal-EIoU loss function,ensuring that the updated loss function emphasizes higher-quality bounding *** YOLOv8-CBAM algorithm can effectively detect asparagus stem blight phenotypic images with a mean average precision(mAP)of 95.51%,which is 0.22%,14.99%,1.77%,and 5.71%higher than the YOLOv5,YOLOv7,YOLOv8,and Mask R-CNN models,*** greatly enhances the efficiency of asparagus growers in identifying asparagus stem blight,aids in improving the prevention and control of asparagus stem blight,and is crucial for the application of computer vision in agriculture.

关键词： YOLOv8 asparagus stem blight image recognition pest