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structural transformation of metal–organic framework with constructed tetravalent nickel sites for efficient water oxidation

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Journal of Energy Chemistry 2022年第11期31卷 404-411,I0011页

作者： Weijian Wu Zhen Gao Qun Li Zhiya Wang Shiyin Liu Hongbo Wu Yuanchun Zhao Yalong Jiao Xiaojia Zhao Hebei Key Laboratory of Inorganic Nano-materials College of Chemistry and Materials ScienceHebei Normal UniversityShijiazhuang 050024HebeiChina Hebei Key Laboratory of Photophysics Research and Application College of PhysicsHebei Normal UniversityShijiazhuang 050024HebeiChina State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004HebeiChina

A mixture of Ni and Fe oxides is among the most commonly active catalysts for the oxygen evolution reaction(OER)during the water oxidation process.In particular,Ni oxide incorporated with even a small amount of Fe leads to substantively enhanced OER activity.However,the critical role of Fe species during the electrocatalytic process is still under evaluation.Herein,we report nickel(oxy)hydroxide incorporated with Fe through the surface reconstruction of a bimetallic metal-organic framework(NiFe-MOF)during the water oxidation process.The spectroscopic investigations with theoretical calculations reveal the critical role of Fe in promoting the formation of highly oxidized Ni^(4+),which directly correlates with an enhanced OER activity.Both the geometric and electronic structu res of the as-reconstructed Ni_(1-x)Fe_(x)OOH electrocatalysts can be delicately tuned by the Ni-Fe ratio of the bimetallic NiFe-MOF,further affecting the catalytic activity.As a result,the Ni_(1-x)Fe_(x)OOH derived from Ni_(0.9)Fe_(0.1)-MOF delivers low overpotentials of 260 mV at 10 mA cm^(-2)and 400 mV at 300 mA cm^(-2).

关键词： structural transformation Bimetallic metal-organic framework Oxygen evolution reaction In-situ Raman spectroscopy High-valence metal sites

structural transformation,TFP and High-Quality Development

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China Economist 2022年第1期17卷 70-82页

作者：刘志彪凌永辉 Yangtze River Industrial Economic Research Institute Nanjing UniversityNanjingChina

In this paper,we performed an empirical study on the TFP effect of structural transformation based on panel data of economic growth in 169 countries across the world.Our findings are threefold:First,structural transformation has an inverted U-shaped effect on TFP.When the degree of structural transformation is on the left side of the inflection point,structural transformation is conducive to softening industrial structure and inducing TFP;when the degree of structural transformation is on the right side of the inflection point,structural transformation will induce industrial hollowing out and inhibit TFP.Second,since the reform and opening up program was launched in 1978,China’s structural transformation has evolved from the stage of adaptation to the stage of strategic adjustment with an increasingly evident trend towards a service-based economy,but structural transformation remains on the left side of the inflection point of the inverted U-shaped curve,i.***.the TFP effect of structural transformation is positive.Third,TFP improvement lies at the heart of high-quality development.In pursuing high-quality development,China should lower growth rate expectations,attach greater importance to supply-side structural reforms,and accelerate structural transformation to promote TFP improvement.

关键词： Economic growth structural transformation TFP high-quality development

In-situ observation of structural evolution of single-atom catalysts:From synthesis to catalysis

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ChemPhysMater

ChemPhysMater 2024年第1期3卷 24-35页

作者： Lei Wang Shuyuan Lyu Shuohao Li School of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou 225009China School of Art and Design Huaiyin Institute of TechnologyHuaian 223003China School of Safety Engineering China University of Mining and TechnologyXuzhou 221116China

Atomically dispersed single-atom catalysts(SACs)have been extensively studied over the past decade because of their high atom utilization efficiencies and specific selectivities.Although numerous strategies have been proposed to obtain SACs with high densities and stabilities,the transformation mechanism that occurs during the reaction is still unclear.This review summarizes the structural evolution of SACs in the preparation process and reaction with various electron microscopy techniques at atomic scale under environmental conditions.Current state-of-the-art environmental electron microscopy studies on SACs mainly focus on porous carbons,metals or metal oxides,and some specific composite materials.The dynamic evolution of SACs under various reaction conditions is also investigated in this study.Finally,we highlight the challenges and drawbacks of the current studies and the prospects for the future exploration of SACs with environmental strategies.

关键词： Single-atom catalysts structural transformation Atomization Environmental electron microscope

World’s first implementation of close-fit pipe jacking of twin tunnels for construction of subway station--Innovation in equipment and construction technology

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Frontiers of Engineering Management 2024年第2期11卷 369-376页

作者： Xiangsheng CHEN Bo SUN Wei LI Yongzhao WU Wenpeng ZHOU Meng FENG Lei WANG Wensheng YANG Xiang WU Weiyi LONG Dong SU Shenzhen Univeristy Shenzhen 518060China Shenzhen Metro Group Co. Ltd.Shenzhen 518031China Shenzhen Municipal Design&Research Co. Ltd.Shenzhen 518000China Sinohydro Bureau 11 Co. Ltd.Zhengzhou 450001China China Railway Engineering Equipment Group Co. LTD.Zhengzhou 450000China Shenzhen University Shenzhen 518060China

1 Project overview The Shasan station of Phase II of Shenzhen’s urban rail transit Line 12 is situated in Bao’an District,Shenzhen.It comprises a two-level underground island platform station,measuring 212 m in length,and 22.6 m in width,with an overburden thickness of about 7.0 m.Fig.1 illustrates the presence of a large underground reinforced concrete stormwater culvert,measuring 11.5 m by 3.6 m,traversing the station’s center.

关键词： Subway station close-fit pipe jacking of twin tunnels modular rectangular pipe jacking machine structural transformation equipment construction

Dramatic Difference Between Cu_(20)H_(8)and Cu_(20)H_(9)Clusters in Catalysis

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CCS Chemistry 2024年第6期6卷 1581-1590页

作者： Chun-Yu Liu Tong-Yu Liu Zong-Jie Guan Song Wang Yuan-Yuan Dong Feng Hu De-en Jiang Quan-Ming Wang Department of Chemistry Engineering Research Center of Advanced Rare Earth Materials(Ministry of Education)Tsinghua UniversityBeijing 100084 Jiangsu Engineering Research Centre for Digital Textile Inkjet Printing Key Laboratory of Eco-Textile Jiangnan UniversityMinistry of EducationWuxiJiangsu 214122 Department of Chemical and Biomolecular Engineering Vanderbilt UniversityNashvilleTennessee 37235 Department of Chemistry Vanderbilt UniversityNashvilleTennessee 37235 College of Chemistry and Chemical Engineering Hunan UniversityChangsha 410082 Hefei National Research Center for Physical Sciences at the Microscale School of Chemistry and Materials ScienceUniversity of Science and Technology of ChinaHefeiAnhui 230026

Sensitivity to structure and composition is very challenging to establish in nanocatalysis due to inadequate definition of structures that are very close in composition.We synthesized a pair of atomically precise copper clusters that are very close in composition,[Cu_(20)H_(9)(Tf-dpf)10]·BF4(Cu_(20)H_(9))and[Cu_(20)H_(8)(Tf-dpf)_(10)]·(BF_(4))_(2)(Cu_(20)H_(8)),by using a pyridyl-functionalized flexible amidinate ligand,N,N′-di(5-trifluoromethyl-2-pyridyl)formamidinate.The one-hydride difference in their composition leads to significant variation in geometric and electronic structures and,consequently,distinctly different optical and catalytic properties.Cu_(20)H_(8)exhibits 25 times higher catalytic activity than Cu_(20)H_(9)(96.7%vs 3.7%in yield)in the selective hydrogenation of anα,β-unsaturated aldehyde(cinnamaldehyde)to saturated aldehyde(3-phenylpropanal).Electrospray ionization mass spectrometry combined with density functional theory calculations reveal that the greater ease of dissociation of one Tf-dpf ligand compared to Cu_(20)H_(8)is the key to its higher activity.This work demonstrates a clear case of structure and composition sensitivity in nanocatalysis and that one hydride,out of∼330 atoms in the nanoclusters,can make a huge difference in the catalytic activity.These insights will be useful in the design and synthesis of atomically precise nanocatalysts.

关键词： copper cluster hydride amidinate ligand structural transformation hydrogenation catalysis

An old story with new insight into the structural transformation and radical production of micron-scale zero-valent iron on successive reactivities

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Chinese Chemical Letters 2020年第10期31卷 2634-2640页

作者： Xinhao Wang Xueting Pu Yue Yuan Yunjie Xiang Yuling Zhang Zhaokun Xiong Gang Yao Bo Lai State Key Laboratory of Hydraulics and Mountain River Engineering College of Architecture and EnvironmentSichuan UniversityChengdu 610065China Sino-German Centre for Water and Health Research Sichuan UniversityChengdu 610065China National Engineering Laboratory for Clean Technology of Leather Manufacture College of Biomass Science and EngineeringSichuan UniversityChengdu 610065China Institute of Environmental Engineering RWTH Aachen UniversityAachen 52062Germany

It is generally recognized that the formation and accumulation of iron oxides on the surface of zero-valent iron(Fe^(0))resulting in significant decrease of contaminant degradation rates during the long-term reactions.However,in this study,we found that the removal efficiencies of p-nitrophenol(PNP)by micro zero-valent iron(mFe^(0))could maintain at the satisfactory level in the process of continuous reactions(20 cycles).The removal rate constant(0.1779 min^(-1))of the 5th cycle was 6.74 times higher than that of the 1streaction(0.0264 min^(-1)),even the 20th cycle(0.0371 min^(-1))was higher than that of the 1st reaction.Interestingly,almost no dissolved iron was detected in the solution,and the total iron concentrations decreased dramatically with the process of continuous reactions.The results of scanning electron microscope and energy dispersive spectrometry(SEM-EDS)and X-ray diffraction(XRD)revealed that the structure and composition of corrosion products change from amorphous to highly crystal with the increase of the number of cycles.The corrosion products were mainly magnetite(Fe_(3)O_(4))and a small part of maghemite(γ-Fe_(2)O_(3)),which were in the form of micro sphe res on the surface of mFe^(0).The formation of surface oxidation shell hindered the release of Fe^(2+).X-ray photoelectron spectroscopy(XPS)results illustrated that partial Fe3O_(4) could be converted into y-Fe_(2)O_(3).Electrochemical analysis proved that the electron transfer rate of mFe^(0) increased with the formation of the oxides shell.However,the consumption of iron core and thicker oxide film weakened the electron transfer rate.Besides,the quenching experiments indicated that the reaction activity of mFe^(0) could be enhanced with the addition of scavengers.This study deepened the understanding of the structural transformation and radical production of mFe^(0) in continuous reactions.

关键词： Zero-valent iron Iron oxides p-Nitrophenol structural transformation Successive reactivities

Hcp-icosahedron structural transformation induced by the change in Ag concentration during the freezing of (CoAg)_(561) clusters

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Chinese Physics B 2012年第4期21卷 424-427页

作者：肖绪洋 School of Electronics Engineering Chongqing University of Arts and SciencesChongqing 402160China

The synergy effect of alloy elements in bimetallic clusters can be used to tune the chemical and physical properties. Research on the influences of alloy concentration and distribution on the frozen structure of bimetallic clusters plays a key rolc in exploring new structural materials. In this paper, we study the influence of Ag concentration on the frozen structure of the （AgCo）561 cluster by using molecular dynamics simulation with a general embedded atom method. The results indicate that tt^e structure and chemical ordering of the （AgCo）561 cluster are strongly related to Ag concentration. Hcp-icosahedron structural transformation in the frozen （CoAg）561 cluster can be induced by changing Ag concentration. The chemical ordering also transforms to Janus-like Co Ag from core-shell Co-Ag.

关键词： bimetallic cluster freeze molecular dynamics structural transformation

A Unique Solvent-Induced structural transformation of Two Acentric [Zn2（H2O）（Hdtim）2] Isomers

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Chinese Journal of Chemistry 2012年第9期30卷 2232-2236页

作者：党琴琴冀芳张献明 School of Chemistry&Material Science Shanxi Normal UniversityLinfenShanxi 041004China

Solvent-induced structural transformation was observed in two layered supramolecular isomers of [Zn2（H2O）（Hdtim）2] （H3dtim--4,5-ditetrazoyl-imidazole）. structural analyses revealed that the two isomers have the similar geometry of Zn, coordination mode of Hdtim2-, and topology. Their structural differences only arise from different arrangement of the layers which seemingly corresponds to cooperative clockwise and counter-clockwise 90° rotation of the adjacent layers. This is a quite unique solvent-dependent supramolecular isomerism in coordination polymers.

关键词： structural transformation isomers packing fashion

A rare porous zinc phosphonocarboxylate framework with high thermal stability and interesting structural transformation

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Chinese Chemical Letters 2018年第6期29卷 959-962页

作者： Yan-Jie Qi Jin-Hua Liu Wen-Xu Zheng Xin-Xiong Li Shou-Tian Zheng State Key Laboratory of Photocatalysis on Energy and Environment College of Chemistry Fuzhou University

A rare porous zinc-organic framework with ultrahigh thermal stability over 500℃ was obtained, which exhibits a CaF2-type topology formed by 8-connected tetranuclear Zn4 clusters and 4-connected phosphonocarboxylate ligands. Interestingly, the similar reactions to the 2 zinc-organic framework but in the absence of H2 O or by the replacement of Zn2＋with Co2＋can yield three different 3 D cluster-based frameworks but with the same CaF2-type topology.

关键词： Phosphonocarboxylate ligand Metal-organic framework Stability structural transformation Gas adsorption