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Insights into the kinetics–morphology relationship of 1-, 2-, and 3D TiNb_(2)O_(7) anodes for Li-ion storage

Nano Research 2024年第4期17卷 2770-2780页

作者： Wenlei Xu Yaolin Xu Veronika Grzimek Andrea Martin Thorsten Schultz Patrícia ARusso Yan Lu Norbert Koch Nicola Pinna Department of Chemistry IRIS Adlershof and the Center for the Science of Materials BerlinHumboldt-Universität zu BerlinBrook-Taylor-Str.212489 BerlinGermany Department of Electrochemical Energy Storage Helmholtz-Zentrum Berlin für Materialien und EnergieHahn-Meitner-Platz 114109 BerlinGermany Institut für Physik and IRIS Adlershof Humboldt-Universität zu BerlinBrook-Taylor-Str.212489 BerlinGermany Joint Research Group of Molecular Systems Helmholtz-Zentrum Berlin für Materialien und Energie12489 BerlinGermany

understanding the influence of electrode material’s morphology on electrochemical behavior is of great significance for the development of rechargeable batteries,however,such studies are often limited by the inability to precisely control the morphology of electrode materials.Herein,nanostructured titanium niobium oxides(TiNb_(2)O_(7))with three different morphologies(one-dimensional(1D),two-dimensional(2D),and three-dimensional(3D))were synthesized via a facile microwave-assisted solvothermal method.The influence of the morphological dimension of TiNb_(2)O_(7) as electrode material on the electrochemical performance in Li-ion batteries(LIBs)and the underlying correlation with the electrochemical kinetics were studied in detail.2D TiNb_(2)O_(7)(TNO-2D)shows a superior rate capability and cycling stability,associated with improved kinetics for charge transfer and Li-ion diffusion,compared to the 1D and 3D materials.Operando X-ray diffraction measurements reveal the structural stability and crystallographic evolution of TNO-2D upon lithiation and delithiation and correlate the Li-ion diffusion kinetics with the lattice evolution during battery charge and discharge.Moreover,carbon-coated TNO-2D achieves enhanced rate capability(205 mAh·g^(-1) at 50 C)and long-term cycling stability(87%after 1000 cycles at 5 C).This work provides insights into the rational morphology design of electrode materials for accelerated charge transfer and enhanced fast-charging capability,pushing forward the development of electrode materials for high-power rechargeable batteries in future energy storage.

关键词： morphological dimension electrochemical kinetics lithium-ion batteries TiNb_(2)O_(7) structural evolution

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Anomalies in the short-range local environment and atomic diffusion in single crystalline equiatomic CrMnfeCoNi highentropy alloy

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Nano Research 2024年第6期17卷 5336-5348页

作者： Alevtina Smekhova Daniel Gaertner Alexei Kuzmin Ana Guilherme Buzanich Goetz Schuck Ivo Zizak Gerhard Wilde Kirill V.Yusenko Sergiy Divinski helmholtz-zentrum berlin für Materialien und energie(HZB) D-12489 BerlinGermany Institute of Materials Physics University of MünsterD-48149 MünsterGermany Institute of Solid State Physics University of LatviaLV-1063 RigaLatvia Bundesanstalt für Materialforschung und–prüfung(BAM) D-12489 BerlinGermany

Multi-edge extended X-ray absorption fine structure(EXAfS)spectroscopy combined with reverse Monte Carlo(RMC)simulations was used to probe the details of element-specific local coordinations and component-dependent structure relaxations in single crystalline equiatomic CrMnfeCoNi high-entropy alloy as a function of the annealing temperature.Two representative states,namely a high-temperature state,created by annealing at 1373 K,and a low-temperature state,produced by long-term annealing at 993 K,were compared in detail.Specific features identified in atomic configurations of particular principal components indicate variations in the local environment distortions connected to different degrees of compositional disorder at the chosen representative temperatures.The detected changes provide new atomistic insights and correlate with the existence of kinks previously observed in the Arrhenius dependencies of component diffusion rates in the CrMnfeCoNi high-entropy alloy.

关键词： high-entropy alloys diffusion short-range order extended X-ray absorption fine structure(EXAfS) reverse Monte Carlo

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Recent advances in core-shell organic framework-based photocatalysts for energy conversion and environmental remediation

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Journal of Energy Chemistry 2024年第8期95卷 168-199页

作者： Qibing Dong Ximing Li Yanyan Duan Qingyun Tian Xinxin Liang Yiyin Zhu Lin Tian Junjun Wang Atif Sial Yongqian Cui Ke Zhao Chuanyi Wang School of Environmental Science and Engineering Shaanxi University of Science and Technology Guangdong Engineering Technology Research Center for Environmental Purification and functional Materials Guangzhou Institute of Industrial Intelligence helmholtz-zentrum berlin für Materialien und energie Jiangxi Key Lab of flexible Electronics Flexible Electronics Innovation Institute Jiangxi Science and Technology Normal University

Direct conversion of solar energy into chemical energy in an environmentally friendly manner is one of the most promising strategies to deal with the environmental pollution and energy crisis. Among a variety of materials developed as photocatalysts, the core-shell metal/covalent-organic framework（MOf or COf）photocatalysts have garnered significant attention due to their highly porous structure and the adjustability in both structure and functionality. The existing reviews on core-shell organic framework photocatalytic materials have mainly focused on core-shell MOf materials. However, there is still a lack of indepth reviews specifically addressing the photocatalytic performance of core-shell COfs and MOfs@COfs. Simultaneously, there is an urgent need for a comprehensive review encompassing these three types of core-shell structures. Based on this, this review aims to provide a comprehensive understanding and useful guidelines for the exploration of suitable core-shell organic framework photocatalysts towards appropriate photocatalytic energy conversion and environmental governance. firstly, the classification, synthesis, formation mechanisms, and reasonable regulation of core-shell organic framework were summarized. Then, the photocatalytic applications of these three kinds of core-shell structures in different areas, such as H2evolution, CO2reduction, and pollutants degradation are emphasized. finally, the main challenges and development prospects of core-shell organic framework photocatalysts were introduced. This review aims to provide insights into the development of a novel generation of efficient and stable core-shell organic framework materials for energy conversion and environmental remediation.

关键词： Core-shell structure Energy conversion Environmental remediation Organic framework Photocatalysis

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Anomalous thermal expansion and enhanced magnetocaloric effect in <001>-textured Mnxfe5–xSi3alloys

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Rare Metals 2024年第5期43卷 2263-2274页

作者： Yong Gong Xue-fei Miao Tapas Samanta Chris Taake Jun Liu feng-Jiao Qian Yan-Yan Shao Yu-Jing Zhang Qing-Yong Ren Luana Caron feng Xu MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology School of Materials Science and Engineering Nanjing University of Science and Technology Department of Physics Bielefeld University College of Physics Nanjing University of Aeronautics and Astronautics Institute of High Energy Physics Chinese Academy of Sciences Spallation Neutron Source Science Center Guangdong-Hong Kong-Macao Joint Laboratory for Neutron Scattering Science and Technology helmholtz-zentrum berlin fu¨r Materialien und energie

The development of zero and negative therma expansion （i.e.,ZTE and NTE） materials is of crucial importance to the control of undesirable thermal expansion for high-precision devices.In the present work,ZTE and NTE were obtained in directionally-solidified Mnxfe5–xSi3alloys with a strongtexture,in striking contrast to positive thermal expansion in their isotropic counterparts Magnetometry and in-situ X-ray diffraction （XRD） measurements were performed to uncover the origin of the anomalous thermal expansion.Magnetic measurements indicate a strong easy-plane magnetocrystalline anisotropy in the textured samples,where the magnetic moments are aligned within the ab plane of the hexagonal structure Temperature-dependent XRD on the x=1 sample reveals a ZTE character in the ab plane that is coupled to a ferromagnetic transition.As a result,the macroscopic ZTE(～0.22×10–6K-1) in the x=1 sample can be attributed to the microscopic magneto volume effect within the ab plane,which is realized by the introduction of the-textured microstructure.Besides,the competition between antiferromagnetic and ferromagnetic exchange coupling leads to NTE in textured x=1.5 and 2 samples.Additionally,textured x=1 sample displays enhanced magnetocaloric properties as compared to the conventional counterparts with randomly-oriented grains.Consequently this work demonstrates a new strategy toward the exploration of anomalous thermal expansion properties as well as the enhancement of magnetocaloric properties for materials with a strong magnetocrystalline anisotropy.

关键词： Mnfe 4 Si 3 Magnetocaloric effect Magnetic phase transition Negative thermal expansion

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Characterization and modeling of the temperature-dependent thermal conductivity in sintered porous silicon-aluminum nanomaterials

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Nano Research 2022年第6期15卷 5663-5670页

作者： Danny Kojda Tommy Hofmann Natalia Gostkowska-Lekner Klaus Habicht Department Dynamics and Transport in Quantum Materials Helmholtz-Zentrum Berlin für Materialien und Energie GmbHBerlin D-14109Germany Institute of Physics and Astronomy University of PotsdamPotsdam D-14476Germany

Nanostructured silicon and silicon-aluminum compounds are synthesized by a novel synthesis strategy based on spark plasma sintering(SPS)of silicon nanopowder,mesoporous silicon(pSi),and aluminum nanopowder.The interplay of metal-assisted crystallization and inherent porosity is exploited to largely suppress thermal conductivity.Morphology and temperaturedependent thermal conductivity studies allow us to elucidate the impact of porosity and nanostructure on the macroscopic heat transport.Analytic electron microscopy along with quantitative image analysis is applied to characterize the sample morphology in terms of domain size and interpore distance distributions.We demonstrate that nanostructured domains and high porosity can be maintained in densified mesoporous silicon samples.In contrast,strong grain growth is observed for sintered nanopowders under similar sintering conditions.We observe that aluminum agglomerations induce local grain growth,while aluminum diffusion is observed in porous silicon and dispersed nanoparticles.A detailed analysis of the measured thermal conductivity between 300 and 773 K allows us to distinguish the effect of reduced thermal conductivity caused by porosity from the reduction induced by phonon scattering at nanosized domains.With a modified Landauer/Lundstrom approach the relative thermal conductivity and the scattering length are extracted.The relative thermal conductivity confirms the applicability of Kirkpatrick’s effective medium theory.The extracted scattering lengths are in excellent agreement with the harmonic mean of log-normal distributed domain sizes and the interpore distances combined by Matthiessen’s rule.

关键词： thermal conductivity mesoporous silicon porosity spark plasma sintering nanoscale modeling

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Al-driven peculiarities of local coordination and magnetic properties in single-phase Al_(x)-CrfeCoNi high-entropy alloys

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Nano Research 2022年第6期15卷 4845-4858页

作者： Alevtina Smekhova Alexei Kuzmin Konrad Siemensmeyer Chen Luo Kai Chen florin Radu Eugen Weschke Uwe Reinholz Ana Guilherme Buzanich Kirill V.Yusenko helmholtz-zentrum berlin für Materialien und energie(HZB) D-12489Germany Institute of Solid State Physics University of LatviaLV-1063Latvia Bundesanstalt für Materialforschung und-prüfung(BAM) D-12489Germany

Modern design of superior multi-functional alloys composed of several principal components requires in-depth studies of their local structure for developing desired macroscopic properties.Herein,peculiarities of atomic arrangements on the local scale and electronic states of constituent elements in the single-phase face-centered cubic(fcc)-and body-centered cubic(bcc)-structured high-entropy Alx-CrfeCoNi alloys(x=0.3 and 3,respectively)are explored by element-specific X-ray absorption spectroscopy in hard and soft X-ray energy ranges.Simulations based on the reverse Monte Carlo approach allow to perform a simultaneous fit of extended X-ray absorption fine structure spectra recorded at K absorption edges of each 3d constituent and to reconstruct the local environment within the first coordination shells of absorbers with high precision.The revealed unimodal and bimodal distributions of all five elements are in agreement with structure-dependent magnetic properties of studied alloys probed by magnetometry.A degree of surface atoms oxidation uncovered by soft X-rays suggests different kinetics of oxide formation for each type of constituents and has to be taken into account.X-ray magnetic circular dichroism technique employed at L2,3 absorption edges of transition metals demonstrates reduced magnetic moments of 3d metal constituents in the sub-surface region of in situ cleaned fcc-structured Al0.3-CrfeCoNi compared to their bulk values.Extended to nanostructured versions of multicomponent alloys,such studies would bring new insights related to effects of high entropy mixing on low dimensions.

关键词： high-entropy alloys reverse Monte Carlo magnetism element-specific spectroscopy extended X-ray absorption fine structure(EXAfS) X-ray magnetic circular dichroism(XMCD)

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平衡三阳离子钙钛矿中带隙和电荷传输以实现高效的室内光伏（英文）

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Science China Materials 2024年

作者：唐颖张祖宏刘海瑞马哈茂德·侯赛因·阿尔达马西穆罕默德·比拉尔杨枫杨纪恩秦朝朝杨勇刚李哲刘玉芳李萌 School of Physics Henan Normal University Key Lab for Special functional Materials of Ministry of Education National & Local Joint Engineering Research Center for High-Efficiency Display and Lighting Technology School of Nanoscience and Materials Engineering Collaborative Innovation Center of Nano Functional Materials and ApplicationsHenan University School of Materials Science and Engineering Henan Normal University helmholtz-zentrum berlin für Materialien und energie GmbH Hahn-Meitner-Platz 1 School of Engineering and Materials Science (SEMS) Queen Mary University of London Institute of Physics Henan Academy of Sciences

带隙可调的钙钛矿材料在室内光伏(IPVs)领域具有广阔的应用前景.然而,与室内光相匹配的宽带隙钙钛矿通常导电性较差,缺陷密度较高,往往不利于电荷提取和传输,限制了其光伏特性.在这里,我们通过调节Br/I比,探究了不同带隙三阳离子钙钛矿...

带隙可调的钙钛矿材料在室内光伏(IPVs)领域具有广阔的应用前景.然而,与室内光相匹配的宽带隙钙钛矿通常导电性较差,缺陷密度较高,往往不利于电荷提取和传输,限制了其光伏特性.在这里,我们通过调节Br/I比,探究了不同带隙三阳离子钙钛矿的IPVs特性.研究表明,宽带隙钙钛矿能充分利用室内光,在低照度下能获得较高的开路电压,但高Br/I比的钙钛矿具有较高的缺陷密度,不利于获得高短路电流密度和填充因子.通过进一步研究不同带隙钙钛矿的结晶动力学、缺陷密度和电荷传输特性,我们发现主流观念中高效IPVs着重考虑室内光伏材料的带隙是不全面的,我们证明了通过适当降低宽带隙晶体中的Br含量可以获得室内光伏特性更优异的器件.也就是说,室内光伏晶体材料的制备需要兼顾带隙和电荷传输特性.在此工作中,平衡带隙和电荷传输的器件(Br 0.23, 1.62 eV)在1035 lux的LED灯照射下取得了40.71%的最佳效率.我们的研究为高效室内光伏的设计提供了新思路.

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Radiofrequency induced heating of biodegradable orthopaedic screw implants during magnetic resonance imaging

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Bioactive Materials 2023年第7期25卷 86-94页

作者： Jonathan Espiritu Mostafa Berangi Hanna Cwieka Kamila Iskhakova Andre Kuehne D.C.florian Wieland Berit Zeller-Plumhoff Thoralf Niendorf Regine Willumeit-Römer Jan-Marten Seitz Syntellix AG HannoverGermany MRI.TOOLS GmbH BerlinGermany Charité-Universitätsmedizin berlin Corporate Member of Freie Universität Berlin and Humboldt Universität zu BerlinBerlinGermany berlin Ultrahigh field facility(B.U.f.f.) Max-Delbrueck Center for Molecular Medicine in the Helmholtz AssociationBerlinGermany Institute of Metallic Biomaterials Helmholtz Zentrum HereonGeesthachtGermany

Magnesium(Mg)-based implants have re-emerged in orthopaedic surgery as an alternative to permanent implants.Literature reveals little information on how the degradation of biodegradable implants may introduce safety implications for patient follow-up using medical imaging.Magnetic resonance imaging(MRI)benefits post-surgery monitoring of bone healing and implantation sites.Previous studies demonstrated radiofrequency(Rf)heating of permanent implants caused by electromagnetic fields used in MRI.Our investigation is the first to report the effect of the degradation layer on Rf-induced heating of biodegradable orthopaedic implants.WE43 orthopaedic compression screws underwent in vitro degradation.Imaging techniques were applied to assess the corrosion process and the material composition of the degraded screws.Temperature measurements were performed to quantify implant heating with respect to the degradation layer.for comparison,a commercial titanium implant screw was used.Strongest Rf induced heating was observed for non-degraded WE43 screw samples.Implant heating had shown to decrease with the formation of the degradation layer.No statistical differences were observed for heating of the non-degraded WE43 material and the titanium equivalent.The highest risk of implant Rf heating is most pronounced for Mg-based screws prior to degradation.Amendment to industry standards for MRI safety assessment is warranted to include biodegradable materials.

关键词： Biodegradable implants Magnesium Medical imaging Magnetic resonance imaging Patient safety

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Tracking the phase transformation and microstructural evolution of Sn anode using operando synchrotron X-ray energy-dispersive diffraction and X-ray tomography

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Journal of Energy Chemistry 2023年第1期76卷 429-437,I0011页

作者： Kang Dong fu Sun Andre Hilger Paul H.Kamm Markus Osenberg francisco Garcia-Moreno Ingo Manke Institute of Applied Materials Helmholtz-Zentrum Berlin fur Materialien und EnergieHahn-Meitner-Platz 1Berlin 14109Germany Institute of Materials Science and Technology Technische Universitat BerlinHardenbergstraβe 36Berlin 10623Germany Qingdao Institute of BioEnergy and Bioprocess Technology Chinese Academy of Sciences189 Songling RoadQingdao 266101ShandongChina

Tin(Sn)holds great promise as an anode material for next-generation lithium(Li)ion batteries but suffers from massive volume change and poor cycling performance.To clarify the dynamic chemical and microstructural evolution of Sn anode during lithiation and delithiation,synchrotron X-ray energydispersive diffraction and X-ray tomography are simultaneously employed during Li/Sn cell operation.The intermediate Li-Sn alloy phases during de/lithiation are identified,and their dynamic phase transformation is unraveled which is further correlated with the volume variation of the Sn at particle-and electrode-level.Moreover,we find that the Sn particle expansion/shrinkage induced particle displacement is anisotropic:the displacement perpendicular to the electrode surface(z-axis)is more pronounced compared to the directions(x-and y-axis)along the electrode surface.This anisotropic particle displacement leads to an anisotropic volume variation at the electrode level and eventually generates a net electrode expansion towards the separator after cycling,which could be one of the root causes of mechanical detachment and delamination of electrodes during long-term operation.The unraveled chemical evolution of Li-Sn and deep insights into the microstructural evolution of Sn anode provided here could guide future design and engineering of Sn and other alloy anodes for high energy density Li-and Na-ion batteries.

关键词： Sn anode Li-Sn phase transformation X-ray tomography Operando X-ray diffraction Anisotropic displacement Digital volume correlation(DVC)

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Defect-density control of platinum-based nanoframes with high-index facets for enhanced electrochemical properties

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Nano Research 2019年第11期12卷 2881-2888页

作者： Shaohan Yang Shuna Li Lianghao Song Yipin Lv Zhongyao Duan Chunsheng Li Raphael francesco Praeg Daowei Gao Guozhu Chen School of Chemistry and Chemical Engineering University of JinanJinan250022China Institute for Solar fuels Helmholtz Zentrum Berlin für Materialien und Energie GmbHBerlin14109Germany Young Investigator Group Operando Characterization of Solar fuel Materials Helmholtz-Zentrum Berlin für Materialien und Energie GmbHBerlin12489Germany

Structure-engineered platinum-based nanoframes(Nfs)at the atomic level can effectively improve the catalytic performance for fuel cells and other heterogeneous catalytic fields.We report herein,a microwave-assisted wet-chemical method for the preparation of platinum-copper-cobalt Nfs with tunable defect density and architecture,which exhibit enhanced activity and durability towards the electro-oxidation reactions of methanol(MOR)and formic acid(fAOR).By altering the reduction/capping agents and thus the nucleation/growth kinetics,trimetallic platinum-copper-cobalt hexapod Nfs with different density high-index facets are achieved.Especially,the rough hexapod nanoframes(rh-Nfs)exhibit excellent specific activities towards MOR and fAOR,7.25 and 5.20 times higher than those of benchmark Pt/C,respectively,along with prolonged durability.The excellent activities of the rh-Nfs are assigned to a synergistic effect,including high density of defects and high-index facets,suitable d-band center,and open-framework structure.This synergistic working mechanism opens up a new way for enhancing their electrocatalytic performances by increasing defect density and high-index facets in open-framework platinum-based Nfs.

关键词： nanoframes defect-density high-index facets electrocatalyst

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