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Journal of Materials Science & Technology 2009年第2期25卷 264-268页

作者： xianfeng yang Zhipeng Xie Yong Huang State Key Laboratory of New Ceramics and Fine Processing Department of Materials Science and Engineering Tsinghua University Beijing 100084 China

During thermal debinding in ceramic injection molding, the inhomogeneity of green body is a key origin of cracks. In this study, the impact of low molecular weight binders on the homogeneity of the green body was investigated. Incidence of cracks during thermal debinding indicated that the volume ratio of wax to stearic acid should be out of high viscosity and incompletely wetting region. In these two formulation regions, typical inhomogeneous microstructures were observed. By mercury intrusion method, it was shown that pore size distribution of the debinded compacts was determined by thermal degradation of low molecular weight binders. A particle-rich region model was established to predict the nucleation of cracks caused by solid loading fluctuation. The criterion of cracks nucleation was that local capillary force from solid loading fluctuation was larger than the suction force from the surroundings.

关键词： Ceramic injection molding Cracks Debinding Homogeneity

Analysis of highway performance under mixed connected and regular vehicle environment

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Journal of Intelligent and Connected Vehicles 2021年第2期4卷 68-79页

作者： Zhao Zhang xianfeng(Terry)yang Department of Civil and Environmental Engineering University of UtahSalt Lake CityUSA

Purpose–This study aims to study the connected vehicle(CV)impact on highway operational performance under a mixed CV and regular vehicle(RV)***/methodology/approach–The authors implemented a mixed trafﬁcﬂow model,along with a CV speed control model,in the simulation *** to the different trafﬁc characteristics between CVs and RVs,this researchﬁrst analyzed how the operation of CVs can affect highway capacity under both one-lane and multi-lane cases.A hypothesis was then made that there shall exist a critical CV penetration rate that can signiﬁcantly show the beneﬁt of CV to the overall trafﬁ*** prove this concept,this study simulated the mixed trafﬁc pattern under various ***–The results of this research revealed that performing optimal speed control to CVs will concurrently beneﬁt RVs by improving highway ***,a critical CV penetration rate should exist at a speciﬁed trafﬁc demand level,which can signiﬁcantly reduce the speed difference between RVs and *** results offer effective insight to understand the potential impacts of different CV penetration rates on highway operation ***/value–This approach assumes that there shall exist a critical CV penetration rate that can maximize the beneﬁts of CV *** penetration rate(the proportion of CVs in mixed trafﬁc)is the key factor affecting the impacts of CV on freeway operational *** evaluation criteria for freeway operational performance are using average travel time under different given trafﬁc demand patterns.

关键词： Connected vehicle Highway capacity Mixed trafﬁc Penetration rate Variable speed limit Paper type Research

Effects of different backbone binders on the characteristics of zirconia parts using wax-based binder system via ceramic injection molding

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Journal of Advanced Ceramics 2016年第4期5卷 321-328页

作者： Jiaxin WEN Zhipeng XIE Wenbin CAO xianfeng yang School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100084 China State Key Laboratory of New Ceramics and Fine Processing Department of Materials Science and EngineeringTsinghua University Beijing 100084 China College of Physics and Electronics Science Changsha University of Science & Technology Changsha 410014 China

In this work,various backbone binders were used in wax-based binder system to formulate zirconia parts by ceramic injection molding (CIM).The effect of different backbone binders on the molding,debinding,and sintering behaviors was *** blending process,the feedstock using multi-polymer components exhibited more homogeneous structure compared with that using the mono-polymer ones due to the synergistic effect of *** solvent debinding,some defects such as 'slumping' and 'peeling' appeared in the parts containing ethylene-vinyl acetate copolymer (EVA),but they were not found in the parts with other thermal ***,as for the parts after sintering,the one using low density polyethylene (LDPE) and high density polyethylene (HDPE) as backbone binders presented a more uniform microstructure with finer zirconia grains among all the investigated compositions,and thus obtained the highest flexural strength (～949 MPa) and relative density (～98.9％).

关键词： ceramic injection molding (CIM) ZrO2 backbone binders solvent debinding sintering

Facet-selective growth of MOF-on-MOF heterostructures enables etching-free synthesis of highly-open Co/N-doped carbon nanoframes for efficient catalysis

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Science China Chemistry 2022年第12期65卷 2450-2461页

作者： Yaohui Wu Liyu Chen xianfeng yang Yingwei Li Kui Shen Guangdong Provincial Key Laboratory of Fuel Cell Technology School of Chemistry and Chemical EngineeringSouth China University of TechnologyGuangzhou510640China State Key Laboratory of Pulp and Paper Engineering School of Chemistry and Chemical EngineeringSouth China University of TechnologyGuangzhou510640China Analytical and Testing Centre South China University of TechnologyGuangzhou510640China

Highly-open nanoframe structures consisting of interconnected and exposed ridges are highly desirable for achieving efficient catalysis,but preparing them by a facile etching-free methodology is still a very daunting ***,we propose a novel metal-organic framework(MOF)-assisted and etching-free strategy for the construction of Co/N-doped carbon nanoframes with highly-open and precisely-controllable *** strategy is based on the face-selective epitaxial growth of ZIF-67 on the 36{110}facets of 72-facet ZIF-8 to form an unprecedented anisotropic ZIF-67-on-ZIF-8 heterostructure,which is subsequently pyrolyzed under Ar atmosphere to realize a solid-to-frame *** highly-open nanoframe structure enables the substrates to readily penetrate into the catalyst interior and thereby create additional exposed active sites,which together with the good mass transport,high atomic utilization and increased surface area are responsible for its remarkably enhanced catalytic activity for the biomass valorisation when compared with its solid and closed hollow *** study could shed valuable insights into the design and preparation of various highly-open nanoframes with abundant exposed active species by using an etching-free strategy for efficient catalysis and beyond.

关键词： metal-organic frameworks etching-free synthesis highly-open nanoframes pyrolysis efficient catalysis

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Simple synthesis of a porous Sb/Sb2O3 nanocomposite for a high-capacity anode material in Na-ion batteries

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Nano Research 2017年第5期10卷 1794-1803页

作者： Jun Pan Nana Wang Yanli Zhou xianfeng yang Wenyao Zhou Yitai Qian Jian yang Key Laboratory of Colloid and Interface Chemistry Ministry University Jinan 250100 China of Education School of Chemistry and Chemical Engineering Shandong Analytical and Testing Center South China University of Technology Guangzhou 510640 China Jinan Licheng No.2 High School Jinan 250105 China Department of Chemistry Hefei National Laboratory for Physical Sciences at Microscale University of Science and Technology of China Hefei 230026 China

High-capacity anode materials are highly desirable for sodium ion batteries. Here, a porous Sb/Sb2O3 nanocomposite is successfully synthesized by the mild oxidization of Sb nanocrystals in air. In the composite, Sb contributes good conductivity and Sb2O3 improves cycling stability, particularly within the voltage window of 0.02-1.5 V. It remains at a reversible capacity of 540 mAh-g-1 after 180 cycles at 0.66 A-g-1. Even at 10 A-g-1, the reversible capacity is still preserved at 412 mAh·g-1, equivalent to 71.6% of that at 0.066 A.g-L These results are much better than Sb nanocrystals with a similar size and structure. Expanding the voltage window to 0.02-2.5 V includes the conversion reaction between Sb203 and Sb into the discharge/charge profiles. This would induce a large volume change and high structure strain、stress, deteriorating the cycling stability. The identification of a proper voltage window for Sb/Sb2O3 paves the way for its development in sodium ion batteries.

关键词： Sb/Sb2O3 high-capacity anode material sodium ion batteries

CoFe_2O_4/carbon nanotube aerogels as high performance anodes for lithium ion batteries

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Green Energy & Environment 2017年第2期2卷 160-167页

作者： Xin Sun Xiaoyi Zhu xianfeng yang Jin Sun Yanzhi Xia Dongjiang yang School of Environmental Science and Engineering Collaborative Innovation Center for Marine Biomass Fibers Materials and Textiles of Shandong ProvinceCollege of Automation and Electrical Engineering Qingdao University Analytical and Testing Centre South China University of Technology Queensland Micro- and Nanotechnology Centre (QMNC) Griffith University

High-performance lithium ion batteries(LIBs) require electrode material to have an ideal electrode construction which provides fast ion transport, short solid-state ion diffusion, large surface area, and high electric conductivity. Herein, highly porous three-dimensional(3D)aerogels composed of cobalt ferrite(CoFe_2O_4, CFO) nanoparticles(NPs) and carbon nanotubes(CNTs) are prepared using sustainable alginate as the precursor. The key feature of this work is that by using the characteristic egg-box structure of the alginate, metal cations such as Co^(2+)and Fe^(3+) can be easily chelated via an ion-exchange process, thus binary CFO are expected to be prepared. In the hybrid aerogels, CFO NPs interconnected by the CNTs are embedded in carbon aerogel matrix, forming the 3D network which can provide high surface area, buffer the volume expansion and offer efficient ion and electron transport pathways for achieving high performance LIBs. The as-prepared hybrid aerogels with the optimum CNT content(20 wt%) delivers excellent electrochemical properties, i.e., reversible capacity of 1033 mAh g^(-1) at 0.1 A g^(-1) and a high specific capacity of 874 mAh g^(-1) after 160 cycles at 1 A g^(-1). This work provides a facile and low cost route to fabricate high performance anodes for LIBs.

关键词： Alginate Aerogels Cobalt ferrite Anode Lithium-ion battery

Carbon-coated mesoporous Co9S8 nanoparticles on reduced graphene oxide as a long-life and high-rate anode material for potassium-ion batteries

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Nano Research 2020年第3期13卷 802-809页

作者： Guangyao Ma Xiao Xu Zhenyu Feng Chenjing Hu Yansong Zhu xianfeng yang Jian yang Yitai Qian Key Laboratory of Colloid and Interface Chemistry Ministry of EducationSchool of Chemistry and Chemical EngineeringShandong UniversityJinan250100China Analytical and Testing Center South China University of TechnologyGuangzhou510640China Hefei National Laboratory for Physical Science at Microscale Department of ChemistryUniversity of Science and Technology of ChinaHefei230026China

Carbon-coated mesoporous Co9S8 nanoparticles supported on reduced graphene oxide(rGO)are successfully synthesized by a simple *** composite makes full use of the protection of the carbon layer on the surface,the good conductivity and three-dimensional(3D)structure of rGO,the mesoporous structure and nanoscale size of Co9S8,thereby presenting the excellent electrochemical performances in potassium-ion batteries,407.9 mAh·g^−1 after 100 cycles at 0.2 A·g^−1 and 215.1 mAh·g^−1 at 5 A·g^−1 in rate *** 1,200 cycles at 1.0 A·g^−1,this composite still remains a capacity of 210.8 mAh·g^−*** redox reactions for potassium storage are revealed by ex-situ transmission electron microscope(TEM)/high-resolution TEM(HRTEM)images,selected area electron diffraction(SAED)patterns and X-ray photoelectron spectroscopy(XPS)*** application of this composite as the host of sulfur for Li-S batteries is also *** sustains a capacity of 431.8 mAh·g^−1 after 800 cycles at 3 C,leading to a degradation of 0.052%per *** results confirm the wide applications of this composite for electrochemical energy storage.

关键词： sulfides graphene nanocomposite mesoporous structure potassium ion batteries

Resonance-enhanced multiphoton ionization spectroscopy on the B'~2Σ^+ and B^2Π states of NS

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Chinese Science Bulletin 2007年第5期52卷 596-602页

作者： WANG Ting-Ting LI ChunYan ZHENG xianfeng CHEN yang Hefei National Laboratory for Physical Sciences at Microscale Department of Chemical Physics University of Science and Technology of China Hefei 230026 China

Resonance-enhanced multiphoton ionization (REMPI) spectra of N32S and N34S have been recorded in the range of 35700―40200 cm?1. The radical was generated by a pulsed dc discharge of a mixture of SF6 and N2 under a supersonic free jet condition. All the 16 observed bands of N32S radicals have been as-signed, among which 12 bands belong to three transition progressions (v'=0-4, 0), (v'=1-4, 1) and (v'=2-4, 2) from the X2Π ground state to the B'2Σ+ upper state and the rest correspond to (9, 0), (10, 0), (11, 0) and (12, 0) bands of B2Π-X2Π transition, respectively. Analysis of the rotationally resolved spectra yields exhaustive spectroscopic constants of both the X2Π ground state and the B'2Σ+ excited state. The electronic transition bands of the isotopic molecule N34S have been rotationally analyzed for the first time and the rotational constants of the ground and upper states have been determined simultaneously.

关键词： NS自由基共振增强多光子电离光谱电子跃迁基态转动常数

Resisting metal aggregation in pyrolysis of MOFs towards highdensity metal nanocatalysts for efficient hydrazine assisted hydrogen production

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Nano Research 2023年第5期16卷 6067-6075页

作者： Jieting Ding Danyu Guo Anqian Hu xianfeng yang Kui Shen Liyu Chen Yingwei Li School of Chemistry and Chemical Engineering South China University of TechnologyGuangzhou 510640China Analytical and Testing Centre South China University of TechnologyGuangzhou 510640China South China University of Technology-Zhuhai Institute of Modern Industrial Innovation Zhuhai 519175China

The preparation of supported high-density metal nanoparticles(NPs)is of great importance to boost the performance in heterogeneous *** transformation of metal-organic frameworks(MOFs)has been demonstrated as a promising route for the synthesis of supported metal NPs with high metal loadings,but it is challenge to achieve uniform metal *** we report a strategy of“spatial isolation and dopant anchoring”to resist metal aggregation in the pyrolysis of MOFs through converting a bulk MOF into dual-heteroatom-containing flower-like MOF sheets(B/N-MOF-S).This approach can spatially isolate metal ions and increase the number of anchoring sites,thus efficiently building physical and/or chemical barriers to cooperatively prevent metal NPs from aggregation in the high-temperature transformation *** thermolysis at 1,000℃,the B/N-MOFS affords B,N co-doped carbon-supported Co NPs(Co/BNC)with uniform dispersion and a high Co loading of 37.3 wt.%,while untreated bulk MOFs yield much larger sizes and uneven distribution of Co *** as-obtained Co/BNC exhibits excellent electrocatalytic activities in both hydrogen evolution and hydrazine oxidation reactions,only a voltage of 0.617 V at a high current density of 100 mA·cm^(−2)is required when applied to a two-electrode overall hydrazine splitting electrolyzer.

关键词： electrocatalysis metal-organic frameworks metal nanoparticles overall hydrazine splitting thermal transformation

Comparative study of China and USA public private partnerships in public transportation

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Journal of Modern Transportation 2016年第3期24卷 215-223页

作者： Zhijie Dong Meicheng Wang xianfeng yang School of Civil and Environmental Engineering Cornell University Department of City and Regional Planning Cornell University Department of Civil Construction& Environmental EngineeringSan Diego State University

As an effective alternative approach to provide goods and services for public infrastructure, the Public Private Partnership （PPP） has been studied extensively over the past few decades. On a global scale, China and the United States have developed cooperation on PPP projects in various areas. To perform a comparative study, this paper analyzes how PPP projects work in both countries for public transportation. The basic features, types, and phases of PPPs in public transportation are introduced first, fol- lowed by a thorough discussion on their advantages and challenges. This paper adopts a case study method to analyze the achievements and problems of PPP projects in both countries and then proposes important findings and suggestions for future research.

关键词： Public private partnership Publictransportation China USA