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  • Thermal meta-device in analogue of zero-index photonics
    Nat. Mater. (IF 39.235) Pub Date : 2018-12-03
    Ying Li, Ke-Jia Zhu, Yu-Gui Peng, Wei Li, Tianzhi Yang, He-Xiu Xu, Hong Chen, Xue-Feng Zhu, Shanhui Fan, C.-W. Qiu

    Inspired by the developments in photonic metamaterials, the concept of thermal metamaterials has promised new avenues for manipulating the flow of heat. In photonics, the existence of natural materials with both positive and negative permittivities has enabled the creation of metamaterials with a very wide range of effective parameters. In contrast, in conductive heat transfer, the available range of thermal conductivities in natural materials is far narrower, strongly restricting the effective parameters of thermal metamaterials and limiting possible applications in extreme environments. Here, we identify a rigorous correspondence between zero index in Maxwell’s equations and infinite thermal conductivity in Fourier’s law. We also propose a conductive system with an integrated convective element that creates an extreme effective thermal conductivity, and hence by correspondence a thermal analogue of photonic near-zero-index metamaterials, a class of metamaterials with crucial importance in controlling light. Synergizing the general properties of zero-index metamaterials and the specific diffusive nature of thermal conduction, we theoretically and experimentally demonstrate a thermal zero-index cloak. In contrast with conventional thermal cloaks, this meta-device can operate in a highly conductive background and the cloaked object preserves great sensitivity to external temperature changes. Our work demonstrates a thermal metamaterial which greatly enhances the capability for molding the flow of heat.

    更新日期:2018-12-04
  • Regioselective surface encoding of nanoparticles for programmable self-assembly
    Nat. Mater. (IF 39.235) Pub Date : 2018-12-03
    Gang Chen, Kyle J. Gibson, Di Liu, Huw C. Rees, Jung-Hoon Lee, Weiwei Xia, Ruoqian Lin, Huolin L. Xin, Oleg Gang, Yossi Weizmann

    Surface encoding of colloidal nanoparticles with DNA is fundamental for fields where recognition interaction is required, particularly controllable material self-assembly. However, regioselective surface encoding of nanoparticles is still challenging because of the difficulty associated with breaking the identical chemical environment on nanoparticle surfaces. Here we demonstrate the selective blocking of nanoparticle surfaces with a diblock copolymer (polystyrene-b-polyacrylic acid). By tuning the interfacial free energies of a ternary system involving the nanoparticles, solvent and copolymer, controllable accessibilities to the nanoparticles’ surfaces are obtained. Through the modification of the polymer-free surface region with single-stranded DNA, regioselective and programmable surface encoding is realized. The resultant interparticle binding potential is selective and directional, allowing for an increased degree of complexity of potential self-assemblies. The versatility of this regioselective surface encoding strategy is demonstrated on various nanoparticles of isotropic or anisotropic shape and a total of 24 distinct complex nanoassemblies are fabricated.

    更新日期:2018-12-04
  • Long spin coherence length and bulk-like spin–orbit torque in ferrimagnetic multilayers
    Nat. Mater. (IF 39.235) Pub Date : 2018-12-03
    Jiawei Yu, Do Bang, Rahul Mishra, Rajagopalan Ramaswamy, Jung Hyun Oh, Hyeon-Jong Park, Yunboo Jeong, Pham Van Thach, Dong-Kyu Lee, Gyungchoon Go, Seo-Won Lee, Yi Wang, Shuyuan Shi, Xuepeng Qiu, Hiroyuki Awano, Kyung-Jin Lee, Hyunsoo Yang

    Spintronics relies on magnetization switching through current-induced spin torques. However, because spin transfer torque for ferromagnets is a surface torque, a large switching current is required for a thick, thermally stable ferromagnetic cell, and this remains a fundamental obstacle for high-density non-volatile applications with ferromagnets. Here, we report a long spin coherence length and associated bulk-like torque characteristics in an antiferromagnetically coupled ferrimagnetic multilayer. We find that a transverse spin current can pass through >10-nm-thick ferrimagnetic Co/Tb multilayers, whereas it is entirely absorbed by a 1-nm-thick ferromagnetic Co/Ni multilayer. We also find that the switching efficiency of Co/Tb multilayers partially reflects a bulk-like torque characteristic, as it increases with ferrimagnet thickness up to 8 nm and then decreases, in clear contrast to the 1/thickness dependence of ferromagnetic Co/Ni multilayers. Our results on antiferromagnetically coupled systems will invigorate research towards the development of energy-efficient spintronics.

    更新日期:2018-12-04
  • Real-time insight into the doping mechanism of redox-active organic radical polymers
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-26
    Shaoyang Wang, Fei Li, Alexandra D. Easley, Jodie L. Lutkenhaus

    Organic radical polymers for batteries represent some of the fastest-charging redox active materials available. Electron transport and charge storage must be accompanied by ion transport and doping for charge neutrality, but the nature of this process in organic radical polymers is not well understood. This is difficult to intuitively predict because the pendant radical group distinguishes organic radical polymers from conjugated, charged or polar polymers. Here we show for the first time a quantitative view of in situ ion transport and doping in organic radical polymers during the redox process. Two modes dominate: doping by lithium ion expulsion and doping by anion uptake. The dominance of one mode over the other is controlled by anion type, electrolyte concentration and timescale. These results apply in any scenario in which electrolyte is in contact with a non-conjugated redox active polymer and present a means of quantifying doping effects.

    更新日期:2018-11-27
  • Avoiding common pitfalls in machine learning omic data science
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-26
    Andrew E. Teschendorff

    Avoiding common pitfalls in machine learning omic data science Avoiding common pitfalls in machine learning omic data science, Published online: 26 November 2018; doi:10.1038/s41563-018-0241-z This Comment describes some of the common pitfalls encountered in deriving and validating predictive statistical models from high-dimensional data. It offers a fresh perspective on some key statistical issues, providing some guidelines to avoid pitfalls, and to help unfamiliar readers better assess the reliability and significance of their results.

    更新日期:2018-11-27
  • Highly mechanosensitive ion channels from graphene-embedded crown ethers
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-26
    A. Fang, K. Kroenlein, D. Riccardi, A. Smolyanitsky

    The ability to tune ionic permeation across nanoscale pores profoundly impacts diverse fields from nanofluidic computing to drug delivery. Here, we take advantage of complex formation between crown ethers and dissolved metal ions to demonstrate graphene-based ion channels highly sensitive to externally applied lattice strain. We perform extensive room-temperature molecular dynamics simulations of the effects of tensile lattice strain on ion permeation across graphene-embedded crown ether pores. Our findings suggest the first instance of solid-state ion channels with an exponential permeation sensitivity to strain, yielding an order of magnitude ion current increase for 2% of isotropic lattice strain. Significant permeation tuning is also shown to be achievable with anisotropic strains. Finally, we demonstrate strain-controllable ion sieving in salt mixtures. The observed high mechanosensitivity is shown to arise from strain-induced control over the competition between ion–crown and ion–solvent interactions, mediated by the atomic thinness of graphene.

    更新日期:2018-11-27
  • Scaling-up phase selection
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-23
    Aditya D. Mohite, Jean-Christophe Blancon

    Scaling-up phase selectionScaling-up phase selection, Published online: 23 November 2018; doi:10.1038/s41563-018-0226-yA method to selectively grow pure metallic-phase monolayer transition metal dichalcogenides marks an important step towards industrially viable nano-(opto)electronic technologies based on two-dimensional materials and their hierarchical assemblies.

    更新日期:2018-11-24
  • The materials science imperative in meeting the Sustainable Development Goals
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-23
    Saleem H. Ali

    The materials science imperative in meeting the Sustainable Development GoalsThe materials science imperative in meeting the Sustainable Development Goals, Published online: 23 November 2018; doi:10.1038/s41563-018-0228-9The materials science imperative in meeting the Sustainable Development Goals

    更新日期:2018-11-24
  • Learning from the big picture
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-23
    Philip Ball

    Learning from the big pictureLearning from the big picture, Published online: 23 November 2018; doi:10.1038/s41563-018-0238-7Learning from the big picture

    更新日期:2018-11-24
  • Control by cell size
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-23
    Wendy F. Liu

    Control by cell sizeControl by cell size, Published online: 23 November 2018; doi:10.1038/s41563-018-0225-zMacrophage confinement reduces the ‘late’ inflammatory gene response to lipopolysaccharide through myocardin-related transcription factor, an actin-binding transcription factor.

    更新日期:2018-11-24
  • Be part of the chain
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-23

    Be part of the chainBe part of the chain, Published online: 23 November 2018; doi:10.1038/s41563-018-0245-8There is room for improvement in materials sustainability, provided we examine carefully the whole value chain.

    更新日期:2018-11-24
  • Unrealistic techno-optimism is holding back progress on resource efficiency
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-23
    Julian M. Allwood

    Unrealistic techno-optimism is holding back progress on resource efficiencyUnrealistic techno-optimism is holding back progress on resource efficiency, Published online: 23 November 2018; doi:10.1038/s41563-018-0229-8Unrealistic techno-optimism is holding back progress on resource efficiency

    更新日期:2018-11-24
  • Publisher Correction: Mixed matrix formulations with MOF molecular sieving for key energy-intensive separations
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-20
    Gongping Liu, Valeriya Chernikova, Yang Liu, Kuang Zhang, Youssef Belmabkhout, Osama Shekhah, Chen Zhang, Shouliang Yi, Mohamed Eddaoudi, William J. Koros

    Publisher Correction: Mixed matrix formulations with MOF molecular sieving for key energy-intensive separationsPublisher Correction: Mixed matrix formulations with MOF molecular sieving for key energy-intensive separations, Published online: 20 November 2018; doi:10.1038/s41563-018-0253-8Publisher Correction: Mixed matrix formulations with MOF molecular sieving for key energy-intensive separations

    更新日期:2018-11-21
  • Bio-inspired pneumatic shape-morphing elastomers
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-19
    Emmanuel Siéfert, Etienne Reyssat, José Bico, Benoît Roman

    Shape-morphing structures are at the core of future applications in aeronautics1, minimally invasive surgery2, tissue engineering3 and smart materials4. However, current engineering technologies, based on inhomogeneous actuation across the thickness of slender structures, are intrinsically limited to one-directional bending5. Here, we describe a strategy where mesostructured elastomer plates undergo fast, controllable and complex shape transformations under applied pressure. Similar to pioneering techniques based on soft hydrogel swelling6,7,8,9,10, these pneumatic shape-morphing elastomers, termed here as ‘baromorphs’, are inspired by the morphogenesis of biological structures11,12,13,14,15. Geometric restrictions are overcome by controlling precisely the local growth rate and direction through a specific network of airways embedded inside the rubber plate. We show how arbitrary three-dimensional shapes can be programmed using an analytic theoretical model, propose a direct geometric solution to the inverse problem, and illustrate the versatility of the technique with a collection of configurations.

    更新日期:2018-11-20
  • Metal-induced ordered microporous polymers for fabricating large-area gas separation membranes
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-19
    Zhihua Qiao, Song Zhao, Menglong Sheng, Jixiao Wang, Shichang Wang, Zhi Wang, Chongli Zhong, Michael D. Guiver

    Metal-induced ordered microporous polymers (MMPs), a class of porous polymer, are synthesized from amine-bearing polymers, small organic linkers and divalent metal ions using a polymer-directed chemical synthesis process. Specifically, small organic linkers first coordinate to metal ions, with the resulting unit cells then self-assembling along the extension of polymer chains to construct three-dimensional frameworks. The MMPs demonstrate good controllability of crystal and framework size, as well as hydrolytic stability. MMP dispersions were coated on a modified polysulfone substrate to fabricate MMP/mPSf membranes with an ultrathin selective layer (below 50 nm) and surface areas of >100 cm2. The MMPs are readily fabricated into defect-free thin selective-layered membranes with high CO2 permeance (3,000 GPU) and stable CO2/N2 selectivity (78) under both humid and dry gas feed conditions, demonstrating promising CO2 membrane separation performance. This synthetic methodology could be extended to other polymers, potentially enabling facile synthesis of membrane materials.

    更新日期:2018-11-20
  • Flexible layer-structured Bi2Te3 thermoelectric on a carbon nanotube scaffold
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-19
    Qun Jin, Song Jiang, Yang Zhao, Dong Wang, Jianhang Qiu, Dai-Ming Tang, Jun Tan, Dong-Ming Sun, Peng-Xiang Hou, Xing-Qiu Chen, Kaiping Tai, Ning Gao, Chang Liu, Hui-Ming Cheng, Xin Jiang

    Inorganic chalcogenides are traditional high-performance thermoelectric materials. However, they suffer from intrinsic brittleness and it is very difficult to obtain materials with both high thermoelectric ability and good flexibility. Here, we report a flexible thermoelectric material comprising highly ordered Bi2Te3 nanocrystals anchored on a single-walled carbon nanotube (SWCNT) network, where a crystallographic relationship exists between the Bi2Te3 < 1¯21¯0 1 ¯ 2 1 ¯ 0 > orientation and SWCNT bundle axis. This material has a power factor of ~1,600 μW m−1 K−2 at room temperature, decreasing to 1,100 μW m−1 K−2 at 473 K. With a low in-plane lattice thermal conductivity of 0.26 ± 0.03 W m−1 K−1, a maximum thermoelectric figure of merit (ZT) of 0.89 at room temperature is achieved, originating from a strong phonon scattering effect. The origin of the excellent flexibility and thermoelectric performance of the Bi2Te3–SWCNT material is attributed, by experimental and computational evidence, to its crystal orientation, interface and nanopore structure. Our results provide insight into the design and fabrication of high-performance flexible thermoelectric materials.

    更新日期:2018-11-20
  • Thermoelectrics that bend but don’t break
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-19
    Shawn A. Gregory, Mark D. Losego

    Thermoelectrics that bend but don’t break Thermoelectrics that bend but don’t break, Published online: 19 November 2018; doi:10.1038/s41563-018-0227-x Sputtering brittle bismuth telluride onto webs of single-walled carbon nanotubes creates a reliably flexible, high-performance thermoelectric composite.

    更新日期:2018-11-20
  • Inflating to shape
    Nat. Mater. (IF 39.235) Pub Date : 
    Efi Efrati

    Inflating to shape Inflating to shape, Published online: 19 November 2018; doi:10.1038/s41563-018-0232-0 An elastomer sheet with programmed inner channel architecture swiftly shapes into a desired three-dimensional geometry upon the application of pressure.

    更新日期:2018-11-20
  • Ordered polymeric membranes using metals
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-19
    Joshua D. Moon, Benny D. Freeman

    Ordered polymeric membranes using metals Ordered polymeric membranes using metals, Published online: 19 November 2018; doi:10.1038/s41563-018-0235-x By combining metal ions, organic linkers and polymers, ordered frameworks with controlled crystallite size can form. When fabricated into membranes, they combine superlative CO2/N2 separation properties with good hydrolytic stability.

    更新日期:2018-11-20
  • Excess solvent in precipitates
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-12
    Emmanuel Clouet

    Excess solvent in precipitatesExcess solvent in precipitates, Published online: 12 November 2018; doi:10.1038/s41563-018-0224-0Although precipitates’ compositions are theoretically determined by thermodynamics, their formation kinetics can also lead to composition variations that allow further structural evolution, making the precipitation path more complex.

    更新日期:2018-11-13
  • Large Pockels effect in micro- and nanostructured barium titanate integrated on silicon
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-12
    Stefan Abel, Felix Eltes, J. Elliott Ortmann, Andreas Messner, Pau Castera, Tino Wagner, Darius Urbonas, Alvaro Rosa, Ana M. Gutierrez, Domenico Tulli, Ping Ma, Benedikt Baeuerle, Arne Josten, Wolfgang Heni, Daniele Caimi, Lukas Czornomaz, Alexander A. Demkov, Juerg Leuthold, Pablo Sanchis, Jean Fompeyrine

    The electro-optical Pockels effect is an essential nonlinear effect used in many applications. The ultrafast modulation of the refractive index is, for example, crucial to optical modulators in photonic circuits. Silicon has emerged as a platform for integrating such compact circuits, but a strong Pockels effect is not available on silicon platforms. Here, we demonstrate a large electro-optical response in silicon photonic devices using barium titanate. We verify the Pockels effect to be the physical origin of the response, with r42 = 923 pm V−1, by confirming key signatures of the Pockels effect in ferroelectrics: the electro-optic response exhibits a crystalline anisotropy, remains strong at high frequencies, and shows hysteresis on changing the electric field. We prove that the Pockels effect remains strong even in nanoscale devices, and show as a practical example data modulation up to 50 Gbit s−1. We foresee that our work will enable novel device concepts with an application area largely extending beyond communication technologies.

    更新日期:2018-11-13
  • Diffusion-defining atomic-scale spinodal decomposition within nanoprecipitates
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-12
    Angelina Orthacker, Georg Haberfehlner, Johannes Taendl, Maria C. Poletti, Bernhard Sonderegger, Gerald Kothleitner

    Stoichiometric precipitates owe their fixed composition to an ordered crystal structure. Deviations from that nominal value, however, are encountered at times. Here we investigate composition, structure and diffusion phenomena of ordered precipitates that form during heat treatment in an industrially cast Al–Mg–Sc–Zr alloy system. Experimental investigations based on aberration-corrected scanning transmission electron microscopy and analytical tomography reveal the temporal evolution of precipitate ordering and formation of non-equilibrium structures with unprecedented spatial resolution, supported by thermodynamic calculations and diffusion simulations. This detailed view reveals atomic-scale spinodal decomposition to majorly define the ongoing diffusion process. It is illustrated that even small deviations in composition and ordering can have a considerable impact on a system’s evolution, due to the interplay of Gibbs energies, atomic jump activation energies and phase ordering, which may play an important role for multicomponent alloys.

    更新日期:2018-11-13
  • Magneto-ionic control of magnetism using a solid-state proton pump
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-12
    Aik Jun Tan, Mantao Huang, Can Onur Avci, Felix Büttner, Maxwell Mann, Wen Hu, Claudio Mazzoli, Stuart Wilkins, Harry L. Tuller, Geoffrey S. D. Beach

    Voltage-gated ion transport as a means of manipulating magnetism electrically could enable ultralow-power memory, logic and sensor technologies. Earlier work made use of electric-field-driven O2− displacement to modulate magnetism in thin films by controlling interfacial or bulk oxidation states. However, elevated temperatures are required and chemical and structural changes lead to irreversibility and device degradation. Here we show reversible and non-destructive toggling of magnetic anisotropy at room temperature using a small gate voltage through H+ pumping in all-solid-state heterostructures. We achieve 90° magnetization switching by H+ insertion at a Co/GdOx interface, with no degradation in magnetic properties after >2,000 cycles. We then demonstrate reversible anisotropy gating by hydrogen loading in Pd/Co/Pd heterostructures, making metal–metal interfaces susceptible to voltage control. The hydrogen storage metals Pd and Pt are high spin–orbit coupling materials commonly used to generate perpendicular magnetic anisotropy, Dzyaloshinskii–Moriya interaction, and spin–orbit torques in ferromagnet/heavy-metal heterostructures. Thus, our work provides a platform for voltage-controlled spin–orbitronics.

    更新日期:2018-11-13
  • Solving mazes with single-molecule DNA navigators
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-05
    Jie Chao, Jianbang Wang, Fei Wang, Xiangyuan Ouyang, Enzo Kopperger, Huajie Liu, Qian Li, Jiye Shi, Lihua Wang, Jun Hu, Lianhui Wang, Wei Huang, Friedrich C. Simmel, Chunhai Fan

    Molecular devices with information-processing capabilities hold great promise for developing intelligent nanorobotics. Here we demonstrate a DNA navigator system that can perform single-molecule parallel depth-first search on a ten-vertex rooted tree defined on a two-dimensional DNA origami platform. Pathfinding by the DNA navigators exploits a localized strand exchange cascade, which is initiated at a unique trigger site on the origami with subsequent automatic progression along paths defined by DNA hairpins containing a universal traversal sequence. Each single-molecule navigator autonomously explores one of the possible paths through the tree. A specific solution path connecting a given pair of start and end vertices can then be easily extracted from the set of all paths taken by the navigators collectively. The solution path laid out on origami is illustrated with single-molecule imaging. Our approach points towards the realization of molecular materials with embedded computational functions operating at the single-molecule level.

    更新日期:2018-11-06
  • Epitaxial growth of ultraflat stanene with topological band inversion
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-05
    Jialiang Deng, Bingyu Xia, Xiaochuan Ma, Haoqi Chen, Huan Shan, Xiaofang Zhai, Bin Li, Aidi Zhao, Yong Xu, Wenhui Duan, Shou-Cheng Zhang, Bing Wang, J. G. Hou

    Two-dimensional (2D) topological materials, including quantum spin/anomalous Hall insulators, have attracted intense research efforts owing to their promise for applications ranging from low-power electronics and high-performance thermoelectrics to fault-tolerant quantum computation. One key challenge is to fabricate topological materials with a large energy gap for room-temperature use. Stanene—the tin counterpart of graphene—is a promising material candidate distinguished by its tunable topological states and sizeable bandgap. Recent experiments have successfully fabricated stanene, but none of them have yet observed topological states. Here we demonstrate the growth of high-quality stanene on Cu(111) by low-temperature molecular beam epitaxy. Importantly, we discovered an unusually ultraflat stanene showing an in-plane s–p band inversion together with a spin–orbit-coupling-induced topological gap (~0.3 eV) at the Γ point, which represents a foremost group-IV ultraflat graphene-like material displaying topological features in experiment. The finding of ultraflat stanene opens opportunities for exploring two-dimensional topological physics and device applications.

    更新日期:2018-11-06
  • Whirling spins with a ferroelectric
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-05
    Evgeny Y. Tsymbal, Christos Panagopoulos

    Whirling spins with a ferroelectric Whirling spins with a ferroelectric, Published online: 05 November 2018; doi:10.1038/s41563-018-0222-2 Ferroelectric polarization enables the emergence and control of magnetic skyrmions at an oxide interface.

    更新日期:2018-11-06
  • Molecular sieving of ethylene from ethane using a rigid metal–organic framework
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-05
    Rui-Biao Lin, Libo Li, Hao-Long Zhou, Hui Wu, Chaohui He, Shun Li, Rajamani Krishna, Jinping Li, Wei Zhou, Banglin Chen

    There are great challenges in developing efficient adsorbents to replace the currently used and energy-intensive cryogenic distillation processes for olefin/paraffin separation, owing to the similar physical properties of the two molecules. Here we report an ultramicroporous metal–organic framework [Ca(C4O4)(H2O)], synthesized from calcium nitrate and squaric acid, that possesses rigid one-dimensional channels. These apertures are of a similar size to ethylene molecules, but owing to the size, shape and rigidity of the pores, act as molecular sieves to prevent the transport of ethane. The efficiency of this molecular sieve for the separation of ethylene/ethane mixtures is validated by breakthrough experiments with high ethylene productivity under ambient conditions. This material can be easily synthesized at the kilogram scale using an environmentally friendly method and is water-stable, which is important for potential industrial implementation. The strategy of using highly rigid metal–organic frameworks with well defined and rigid pores could also be extended to other porous materials for chemical separation processes.

    更新日期:2018-11-06
  • Ferroelectrically tunable magnetic skyrmions in ultrathin oxide heterostructures
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-05
    Lingfei Wang, Qiyuan Feng, Yoonkoo Kim, Rokyeon Kim, Ki Hoon Lee, Shawn D. Pollard, Yeong Jae Shin, Haibiao Zhou, Wei Peng, Daesu Lee, Wenjie Meng, Hyunsoo Yang, Jung Hoon Han, Miyoung Kim, Qingyou Lu, Tae Won Noh

    Magnetic skyrmions are topologically protected whirling spin texture. Their nanoscale dimensions, topologically protected stability and solitonic nature, together are promising for future spintronics applications. To translate these compelling features into practical spintronic devices, a key challenge lies in achieving effective control of skyrmion properties, such as size, density and thermodynamic stability. Here, we report the discovery of ferroelectrically tunable skyrmions in ultrathin BaTiO3/SrRuO3 bilayer heterostructures. The ferroelectric proximity effect at the BaTiO3/SrRuO3 heterointerface triggers a sizeable Dzyaloshinskii–Moriya interaction, thus stabilizing robust skyrmions with diameters less than a hundred nanometres. Moreover, by manipulating the ferroelectric polarization of the BaTiO3 layer, we achieve local, switchable and nonvolatile control of both skyrmion density and thermodynamic stability. This ferroelectrically tunable skyrmion system can simultaneously enhance the integratability and addressability of skyrmion-based functional devices.

    更新日期:2018-11-06
  • An efficient nanosieve
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-05
    Anastasiya Bavykina, Jorge Gascon

    An efficient nanosieve An efficient nanosieve, Published online: 05 November 2018; doi:10.1038/s41563-018-0223-1 A rigid and easily scalable metal–organic framework is shown to be among the most efficient materials for separating ethylene from ethane.

    更新日期:2018-11-06
  • Author Correction: Antiviral agents: Targeting vesicle size
    Nat. Mater. (IF 39.235) Pub Date : 2018-11-02
    Zhe Fei, Pei-Yong Shi

    Author Correction: Antiviral agents: Targeting vesicle size Author Correction: Antiviral agents: Targeting vesicle size, Published online: 02 November 2018; doi:10.1038/s41563-018-0237-8 Author Correction: Antiviral agents: Targeting vesicle size

    更新日期:2018-11-05
  • Author Correction: Injectable tissue integrating networks from recombinant polypeptides with tunable order
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-31
    Stefan Roberts, Tyler S. Harmon, Jeffrey L. Schaal, Vincent Miao, Kan (Jonathan) Li, Andrew Hunt, Yi Wen, Terrence G. Oas, Joel H. Collier, Rohit V. Pappu, Ashutosh Chilkoti

    Author Correction: Injectable tissue integrating networks from recombinant polypeptides with tunable order Author Correction: Injectable tissue integrating networks from recombinant polypeptides with tunable order, Published online: 31 October 2018; doi:10.1038/s41563-018-0233-z Author Correction: Injectable tissue integrating networks from recombinant polypeptides with tunable order

    更新日期:2018-11-02
  • A tunable magnetic metamaterial based on the dipolar four-state Potts model
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-29
    D. Louis, D. Lacour, M. Hehn, V. Lomakin, T. Hauet, F. Montaigne

    Metamaterials, tunable artificial materials, are useful playgrounds to investigate magnetic systems. So far, artificial Ising spin systems have revealed features such as emergent magnetic monopoles1,2 and charge fragmentation3. Here we present a metasystem composed of a lattice of dipolarly coupled nanomagnets. The magnetic spin of each nanomagnet is constrained to lie along a body diagonal, which yields four possible spin states. We show that the magnetic ordering of this metasystem (antiferromagnetic, ferromagnetic or spin ice like) is determined by the spin states orientation relative to the underlying lattice. The dipolar four-state Potts model explains our experimental observations and sheds light on the role of symmetry, as well as short- and long-range dipolar magnetic interactions, in such non-Ising spin systems.

    更新日期:2018-10-30
  • The role of defects and excess surface charges at finite temperature for optimizing oxide photoabsorbers
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-29
    Matteo Gerosa, Francois Gygi, Marco Govoni, Giulia Galli

    Computational screening of materials for solar to fuel conversion technologies has mostly focused on bulk properties, thus neglecting the structure and chemistry of surfaces and interfaces with water. We report a finite temperature study of WO3, a promising anode for photoelectrochemical cells, carried out using first-principles molecular dynamics simulations coupled with many-body perturbation theory. We identified three major factors determining the chemical reactivity of the material interfaced with water: the presence of surface defects, the dynamics of excess charge at the surface, and finite temperature fluctuations of the surface electronic orbitals. These general descriptors are essential for the understanding and prediction of optimal oxide photoabsorbers for water oxidation.

    更新日期:2018-10-30
  • Biomaterials and engineered microenvironments to control YAP/TAZ-dependent cell behaviour
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-29
    Giovanna Brusatin, Tito Panciera, Alessandro Gandin, Anna Citron, Stefano Piccolo

    Mechanical signals are increasingly recognized as overarching regulators of cell behaviour, controlling stemness, organoid biology, tissue development and regeneration. Moreover, aberrant mechanotransduction is a driver of disease, including cancer, fibrosis and cardiovascular defects. A central question remains how cells compute a host of biomechanical signals into meaningful biological behaviours. Biomaterials and microfabrication technologies are essential to address this issue. Here we review a large body of evidence that connects diverse biomaterial-based systems to the functions of YAP/TAZ, two highly related mechanosensitive transcriptional regulators. YAP/TAZ orchestrate the response to a suite of engineered microenviroments, emerging as a universal control system for cells in two and three dimensions, in static or dynamic fashions, over a range of elastic and viscoelastic stimuli, from solid to fluid states. This approach may guide the rational design of technological and material-based platforms with dramatically improved functionalities and inform the generation of new biomaterials for regenerative medicine applications.

    更新日期:2018-10-30
  • Hybrid photoelectrochemical and photovoltaic cells for simultaneous production of chemical fuels and electrical power
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-29
    Gideon Segev, Jeffrey W. Beeman, Jeffery B. Greenblatt, Ian D. Sharp

    Harnessing solar energy to drive photoelectrochemical reactions is widely studied for sustainable fuel production and versatile energy storage over different timescales. However, the majority of solar photoelectrochemical cells cannot drive the overall photosynthesis reactions without the assistance of an external power source. A device for simultaneous and direct production of renewable fuels and electrical power from sunlight is now proposed. This hybrid photoelectrochemical and photovoltaic device allows tunable control over the branching ratio between two high-value products of solar energy conversion, requires relatively simple modification to existing photovoltaic technologies, and circumvents the photocurrent mismatches that lead to significant loss in tandem photoelectrochemical systems comprising chemically stable photoelectrodes. Our proof-of-concept device is based on a transition metal oxide photoanode monolithically integrated onto silicon that possesses both front- and backside photovoltaic junctions. This integrated assembly drives spontaneous overall water splitting with no external power source, while also producing electricity near the maximum power point of the backside photovoltaic junction. The concept that photogenerated charge carriers can be controllably directed to produce electricity and chemical fuel provides an opportunity to significantly increase the energy return on energy invested in solar fuels systems and can be adapted to a variety of architectures assembled from different materials.

    更新日期:2018-10-30
  • 2D materials-wrapped microparticles
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-23
    Qiyuan He, Hua Zhang

    2D materials-wrapped microparticles 2D materials-wrapped microparticles, Published online: 23 October 2018; doi:10.1038/s41563-018-0202-6 Colloidal microparticles, with polymer composites encapsulated within two separate 2D material sheets, are fabricated by autoperforation, which can carry chemical and electronic information with long-term instability in complex environments.

    更新日期:2018-10-23
  • Prosthetics in war and peace
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-23
    Amos Matsiko

    Prosthetics in war and peace Prosthetics in war and peace, Published online: 23 October 2018; doi:10.1038/s41563-018-0212-4 Emily Mayhew, a historian within the Department of Bioengineering at Imperial College London, talks to Nature Materials about the advances that have been made in medicine and, in particular, prosthetics since World War I.

    更新日期:2018-10-23
  • Autoperforation of 2D materials for generating two-terminal memristive Janus particles
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-23
    Pingwei Liu, Albert Tianxiang Liu, Daichi Kozawa, Juyao Dong, Jing Fan Yang, Volodymyr B. Koman, Max Saccone, Song Wang, Youngwoo Son, Min Hao Wong, Michael S. Strano

    Graphene and other two-dimensional materials possess desirable mechanical, electrical and chemical properties for incorporation into or onto colloidal particles, potentially granting them unique electronic functions. However, this application has not yet been realized, because conventional top-down lithography scales poorly for producing colloidal solutions. Here, we develop an ‘autoperforation’ technique that provides a means of spontaneous assembly for surfaces composed of two-dimensional molecular scaffolds. Chemical vapour deposited two-dimensional sheets can autoperforate into circular envelopes when sandwiching a microprinted polymer composite disk of nanoparticle ink, allowing liftoff into solution and simultaneous assembly. The resulting colloidal microparticles have two independently addressable, external Janus faces that we show can function as an intraparticle array of vertically aligned, two-terminal electronic devices. Such particles demonstrate remarkable chemical and mechanical stability and form the basis of particulate electronic devices capable of collecting and storing information about their surroundings, extending nanoelectronics into previously inaccessible environments.

    更新日期:2018-10-23
  • Targeting vesicle size
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-23
    Jing Zou, Pei-Yong Shi

    Targeting vesicle size Targeting vesicle size, Published online: 23 October 2018; doi:10.1038/s41563-018-0200-8 An amphiphatic peptide has been engineered and is capable of penetrating the blood–brain barrier as well as possessing a potent antiviral activity against Zika and other mosquito-borne viruses.

    更新日期:2018-10-23
  • Chirality meets topology
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-23
    Chandra Shekhar

    Chirality meets topology Chirality meets topology, Published online: 23 October 2018; doi:10.1038/s41563-018-0210-6 By considering the topology of chiral crystals, a new type of massless fermion, connected with giant arc-like surface states, are predicted. Such Kramers–Weyl fermions should manifest themselves in a wide variety of chiral materials.

    更新日期:2018-10-23
  • Reading the atmosphere
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-23
    Philip Ball

    Reading the atmosphere Reading the atmosphere, Published online: 23 October 2018; doi:10.1038/s41563-018-0213-3 Reading the atmosphere

    更新日期:2018-10-23
  • A century of advances in prostheses
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-23

    A century of advances in prostheses A century of advances in prostheses, Published online: 23 October 2018; doi:10.1038/s41563-018-0218-y Prostheses today can trace their roots to the rudimentary designs of the First World War, but since then there have been significant advances that have improved the quality of life of amputees.

    更新日期:2018-10-23
  • Electrically detecting infrared light
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-23
    Zhe Fei

    Electrically detecting infrared light Electrically detecting infrared light, Published online: 23 October 2018; doi:10.1038/s41563-018-0207-1 Researchers have developed a graphene plasmonics detector that is suitable for fast-response and high-resolution detection of infrared photons at room temperature.

    更新日期:2018-10-23
  • Injectable tissue integrating networks from recombinant polypeptides with tunable order
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-15
    Stefan Roberts, Tyler S. Harmon, Jeffery Schaal, Vincent Miao, Kan (Jonathan) Li, Andrew Hunt, Yi Wen, Terrence G. Oas, Joel H. Collier, Rohit V. Pappu, Ashutosh Chilkoti

    Emergent properties of natural biomaterials result from the collective effects of nanoscale interactions among ordered and disordered domains. Here, using recombinant sequence design, we have created a set of partially ordered polypeptides to study emergent hierarchical structures by precisely encoding nanoscale order–disorder interactions. These materials, which combine the stimuli-responsiveness of disordered elastin-like polypeptides and the structural stability of polyalanine helices, are thermally responsive with tunable thermal hysteresis and the ability to reversibly form porous, viscoelastic networks above threshold temperatures. Through coarse-grain simulations, we show that hysteresis arises from physical crosslinking due to mesoscale phase separation of ordered and disordered domains. On injection of partially ordered polypeptides designed to transition at body temperature, they form stable, porous scaffolds that rapidly integrate into surrounding tissue with minimal inflammation and a high degree of vascularization. Sequence-level modulation of structural order and disorder is an untapped principle for the design of functional protein-based biomaterials.

    更新日期:2018-10-16
  • Coatings super-repellent to ultralow surface tension liquids
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-15
    Shuaijun Pan, Rui Guo, Mattias Björnmalm, Joseph J. Richardson, Ling Li, Chang Peng, Nadja Bertleff-Zieschang, Weijian Xu, Jianhui Jiang, Frank Caruso

    High-performance coatings that durably and fully repel liquids are of interest for fundamental research and practical applications. Such coatings should allow for droplet beading, roll off and bouncing, which is difficult to achieve for ultralow surface tension liquids. Here we report a bottom-up approach to prepare super-repellent coatings using a mixture of fluorosilanes and cyanoacrylate. On application to surfaces, the coatings assemble into thin films of locally multi-re-entrant hierarchical structures with very low surface energies. The resulting materials are super-repellent to solvents, acids and bases, polymer solutions and ultralow surface tension liquids, characterized by ultrahigh liquid contact angles (>150°) and negligible roll-off angles (~0°). Furthermore, the coatings are transparent, durable and demonstrate universal liquid bouncing, tailored responsiveness and anti-freezing properties, and are thus a promising alternative to existing synthetic super-repellent coatings.

    更新日期:2018-10-16
  • High-mobility band-like charge transport in a semiconducting two-dimensional metal–organic framework
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-15
    Renhao Dong, Peng Han, Himani Arora, Marco Ballabio, Melike Karakus, Zhe Zhang, Chandra Shekhar, Peter Adler, Petko St. Petkov, Artur Erbe, Stefan C. B. Mannsfeld, Claudia Felser, Thomas Heine, Mischa Bonn, Xinliang Feng, Enrique Cánovas

    Metal–organic frameworks (MOFs) are hybrid materials based on crystalline coordination polymers that consist of metal ions connected by organic ligands. In addition to the traditional applications in gas storage and separation or catalysis, the long-range crystalline order in MOFs, as well as the tunable coupling between the organic and inorganic constituents, has led to the recent development of electrically conductive MOFs as a new generation of electronic materials. However, to date, the nature of charge transport in the MOFs has remained elusive. Here we demonstrate, using high-frequency terahertz photoconductivity and Hall effect measurements, Drude-type band-like transport in a semiconducting, π–d conjugated porous Fe3(THT)2(NH4)3 (THT, 2,3,6,7,10,11-triphenylenehexathiol) two-dimensional MOF, with a room-temperature mobility up to ~ 220 cm2 V–1 s–1. The temperature-dependent conductivity reveals that this mobility represents a lower limit for the material, as mobility is limited by impurity scattering. These results illustrate the potential for high-mobility semiconducting MOFs as active materials in thin-film optoelectronic devices.

    更新日期:2018-10-16
  • Phase-selective synthesis of 1T′ MoS2 monolayers and heterophase bilayers
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-15
    Lina Liu, Juanxia Wu, Liyuan Wu, Meng Ye, Xiaozhi Liu, Qian Wang, Siyao Hou, Pengfei Lu, Lifei Sun, Jingying Zheng, Lei Xing, Lin Gu, Xiangwei Jiang, Liming Xie, Liying Jiao

    Two-dimensional (2D) MoS2, which has great potential for optoelectronic and other applications, is thermodynamically stable and hence easily synthesized in its semiconducting 2H phase. In contrast, growth of its metastable 1T and 1T′ phases is hampered by their higher formation energy. Here we use theoretical calculations to design a potassium (K)-assisted chemical vapour deposition method for the phase-selective growth of 1T′ MoS2 monolayers and 1T′/2H heterophase bilayers. This is realized by tuning the concentration of K in the growth products to invert the stability of the 1T′ and 2H phases. The synthesis of 1T′ MoS2 monolayers with high phase purity allows us to characterize their intrinsic optical and electrical properties, revealing a characteristic in-plane anisotropy. This phase-controlled bottom-up synthesis offers a simple and efficient way of manipulating the relevant device structures, and provides a general approach for producing other metastable-phase 2D materials with unique properties.

    更新日期:2018-10-16
  • Publisher Correction: Large electrostrictive response in lead halide perovskites
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-12
    Bo Chen, Tao Li, Qingfeng Dong, Edoardo Mosconi, Jingfeng Song, Zhaolai Chen, Yehao Deng, Ye Liu, Stephen Ducharme, Alexei Gruverman, Filippo De Angelis, Jinsong Huang

    Publisher Correction: Large electrostrictive response in lead halide perovskites Publisher Correction: Large electrostrictive response in lead halide perovskites, Published online: 12 October 2018; doi:10.1038/s41563-018-0216-0 Publisher Correction: Large electrostrictive response in lead halide perovskites

    更新日期:2018-10-12
  • Publisher Correction: Materials challenges for the Starshot lightsail
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-12
    Harry A. Atwater, Artur R. Davoyan, Ognjen Ilic, Deep Jariwala, Michelle C. Sherrott, Cora M. Went, William S. Whitney, Joeson Wong

    Publisher Correction: Materials challenges for the Starshot lightsail Publisher Correction: Materials challenges for the Starshot lightsail, Published online: 12 October 2018; doi:10.1038/s41563-018-0214-2 Publisher Correction: Materials challenges for the Starshot lightsail

    更新日期:2018-10-12
  • Polarity governs atomic interaction through two-dimensional materials
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-08
    Wei Kong, Huashan Li, Kuan Qiao, Yunjo Kim, Kyusang Lee, Yifan Nie, Doyoon Lee, Tom Osadchy, Richard J Molnar, D. Kurt Gaskill, Rachael L. Myers-Ward, Kevin M. Daniels, Yuewei Zhang, Suresh Sundram, Yang Yu, Sang-hoon Bae, Siddharth Rajan, Yang Shao-Horn, Kyeongjae Cho, Abdallah Ougazzaden, Jeffrey C. Grossman, Jeehwan Kim

    The transparency of two-dimensional (2D) materials to intermolecular interactions of crystalline materials has been an unresolved topic. Here we report that remote atomic interaction through 2D materials is governed by the binding nature, that is, the polarity of atomic bonds, both in the underlying substrates and in 2D material interlayers. Although the potential field from covalent-bonded materials is screened by a monolayer of graphene, that from ionic-bonded materials is strong enough to penetrate through a few layers of graphene. Such field penetration is substantially attenuated by 2D hexagonal boron nitride, which itself has polarization in its atomic bonds. Based on the control of transparency, modulated by the nature of materials as well as interlayer thickness, various types of single-crystalline materials across the periodic table can be epitaxially grown on 2D material-coated substrates. The epitaxial films can subsequently be released as free-standing membranes, which provides unique opportunities for the heterointegration of arbitrary single-crystalline thin films in functional applications.

    更新日期:2018-10-09
  • Programmed assembly of synthetic protocells into thermoresponsive prototissues
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-08
    Pierangelo Gobbo, Avinash J. Patil, Mei Li, Robert Harniman, Wuge H. Briscoe, Stephen Mann

    Although several new types of synthetic cell-like entities are now available, their structural integration into spatially interlinked prototissues that communicate and display coordinated functions remains a considerable challenge. Here we describe the programmed assembly of synthetic prototissue constructs based on the bio-orthogonal adhesion of a spatially confined binary community of protein–polymer protocells, termed proteinosomes. The thermoresponsive properties of the interlinked proteinosomes are used collectively to generate prototissue spheroids capable of reversible contractions that can be enzymatically modulated and exploited for mechanochemical transduction. Overall, our methodology opens up a route to the fabrication of artificial tissue-like materials capable of collective behaviours, and addresses important emerging challenges in bottom-up synthetic biology and bioinspired engineering.

    更新日期:2018-10-09
  • Transparency revealed
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-08
    Rodolfo Miranda

    Transparency revealed Transparency revealed, Published online: 08 October 2018; doi:10.1038/s41563-018-0201-7 Advances in understanding the physics behind remote epitaxy, a technique of growing films that ‘copy’ the substrate crystal structure through 2D material interlayer, facilitates the production of ultrathin components for device heterointegration.

    更新日期:2018-10-09
  • Interparticle hydrogen bonding can elicit shear jamming in dense suspensions
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-08
    Nicole M. James, Endao Han, Ricardo Arturo Lopez de la Cruz, Justin Jureller, Heinrich M. Jaeger

    Dense suspensions of hard particles in a liquid can exhibit strikingly counter-intuitive behaviour, such as discontinuous shear thickening (DST)1,2,3,4,5,6,7 and reversible shear jamming (SJ) into a state where flow is arrested and the suspension is solid-like8,9,10,11,12. A stress-activated crossover from hydrodynamic interactions to frictional particle contacts is key for these behaviours2,3,4,6,7,9,13. However, in experiments, many suspensions show only DST, not SJ. Here we show that particle surface chemistry plays a central role in creating conditions that make SJ readily observable. We find the system’s ability to form interparticle hydrogen bonds when sheared into contact elicits SJ. We demonstrate this with charge-stabilized polymer microspheres and non-spherical cornstarch particles, controlling hydrogen bond formation with solvents. The propensity for SJ is quantified by tensile tests12 and linked to an enhanced friction by atomic force microscopy. Our results extend the fundamental understanding of the SJ mechanism and open avenues for designing strongly non-Newtonian fluids.

    更新日期:2018-10-09
  • Topological quantum properties of chiral crystals
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-01
    Guoqing Chang, Benjamin J. Wieder, Frank Schindler, Daniel S. Sanchez, Ilya Belopolski, Shin-Ming Huang, Bahadur Singh, Di Wu, Tay-Rong Chang, Titus Neupert, Su-Yang Xu, Hsin Lin, M. Zahid Hasan

    Chiral crystals are materials with a lattice structure that has a well-defined handedness due to the lack of inversion, mirror or other roto-inversion symmetries. Although it has been shown that the presence of crystalline symmetries can protect topological band crossings, the topological electronic properties of chiral crystals remain largely uncharacterized. Here we show that Kramers–Weyl fermions are a universal topological electronic property of all non-magnetic chiral crystals with spin–orbit coupling and are guaranteed by structural chirality, lattice translation and time-reversal symmetry. Unlike conventional Weyl fermions, they appear at time-reversal-invariant momenta. We identify representative chiral materials in 33 of the 65 chiral space groups in which Kramers–Weyl fermions are relevant to the low-energy physics. We determine that all point-like nodal degeneracies in non-magnetic chiral crystals with relevant spin–orbit coupling carry non-trivial Chern numbers. Kramers–Weyl materials can exhibit a monopole-like electron spin texture and topologically non-trivial bulk Fermi surfaces over an unusually large energy window.

    更新日期:2018-10-02
  • Julia Randall Weertman (1926–2018)
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-01
    Katherine T. Faber

    Julia Randall Weertman (1926–2018) Julia Randall Weertman (1926–2018), Published online: 01 October 2018; doi:10.1038/s41563-018-0195-1 Pioneering materials scientist and inspiring mentor.

    更新日期:2018-10-02
  • Oxidation states and ionicity
    Nat. Mater. (IF 39.235) Pub Date : 2018-10-01
    Aron Walsh, Alexey A. Sokol, John Buckeridge, David O. Scanlon, C. Richard A. Catlow

    The concepts of oxidation state and atomic charge are entangled in modern materials science. We distinguish between these quantities and consider their fundamental limitations and utility for understanding material properties. We discuss the nature of bonding between atoms and the techniques that have been developed for partitioning electron density. While formal oxidation states help us count electrons (in ions, bonds, lone pairs), variously defined atomic charges are usefully employed in the description of physical processes including dielectric response and electronic spectroscopies. Such partial charges are introduced as quantitative measures in simple mechanistic models of a more complex reality, and therefore may not be comparable or transferable. In contrast, oxidation states are defined to be universal, with deviations constituting exciting challenges as evidenced in mixed-valence compounds, electrides and highly correlated systems. This Perspective covers how these concepts have evolved in recent years, our current understanding and their significance.

    更新日期:2018-10-02
  • Retraction Note: Large local lattice expansion in graphene adlayers grown on copper
    Nat. Mater. (IF 39.235) Pub Date : 2018-09-27
    Chaoyu Chen, José Avila, Hakim Arezki, Van Luan Nguyen, Jiahong Shen, Marcin Mucha-Kruczyński, Fei Yao, Mohamed Boutchich, Yue Chen, Young Hee Lee, Maria C. Asensio

    Retraction Note: Large local lattice expansion in graphene adlayers grown on copper Retraction Note: Large local lattice expansion in graphene adlayers grown on copper, Published online: 27 September 2018; doi:10.1038/s41563-018-0185-3 Retraction Note: Large local lattice expansion in graphene adlayers grown on copper

    更新日期:2018-09-28
  • Ultrafast water harvesting and transport in hierarchical microchannels
    Nat. Mater. (IF 39.235) Pub Date : 2018-09-24
    Huawei Chen, Tong Ran, Yang Gan, Jiajia Zhou, Yi Zhang, Liwen Zhang, Deyuan Zhang, Lei Jiang

    Various natural materials have hierarchical microscale and nanoscale structures that allow for directional water transport. Here we report an ultrafast water transport process in the surface of a Sarracenia trichome, whose transport velocity is about three orders of magnitude faster than those measured in cactus spine and spider silk. The high velocity of water transport is attributed to the unique hierarchical microchannel organization of the trichome. Two types of ribs with different height regularly distribute around the trichome cone, where two neighbouring high ribs form a large channel that contains 1–5 low ribs that define smaller base channels. This results in two successive but distinct modes of water transport. Initially, a rapid thin film of water is formed inside the base channels (Mode I), which is followed by ultrafast water sliding on top of that thin film (Mode II). This two-step ultrafast water transport mechanism is modelled and experimentally tested in bio-inspired microchannels, which demonstrates the potential of this hierarchal design for microfluidic applications.

    更新日期:2018-09-25
  • Large electrostrictive response in lead halide perovskites
    Nat. Mater. (IF 39.235) Pub Date : 2018-09-24
    Bo Chen, Tao Li, Qingfeng Dong, Edoardo Mosconi, Jingfeng Song, Zhaolai Chen, Yehao Deng, Ye Liu, Stephen Ducharme, Alexei Gruverman, Filippo De Angelis, Jinsong Huang

    Lead halide perovskites have demonstrated outstanding performance in photovoltaics, photodetectors, radiation detectors and light-emitting diodes. However, the electromechanical properties, which are the main application of inorganic perovskites, have rarely been explored for lead halide perovskites. Here, we report the discovery of a large electrostrictive response in methylammonium lead triiodide (MAPbI3) single crystals. Under an electric field of 3.7 V µm−1, MAPbI3 shows a large compressive strain of 1%, corresponding to a mechanical energy density of 0.74 J cm−3, comparable to that of human muscles. The influences of piezoelectricity, thermal expansion, intrinsic electrostrictive effect, Maxwell stress, ferroelectricity, local polar fluctuation and methylammonium cation ordering on this electromechanical response are excluded. We speculate, using density functional theory, that electrostriction of MAPbI3 probably originates from lattice deformation due to formation of additional defects under applied bias. The discovery of large electrostriction in lead iodide perovskites may lead to new potential applications in actuators, sonar and micro-electromechanical systems and aid the understanding of other field-dependent material properties.

    更新日期:2018-09-25
  • Golden single-atomic-site platinum electrocatalysts
    Nat. Mater. (IF 39.235) Pub Date : 2018-09-24
    Paul N. Duchesne, Z. Y. Li, Christopher P. Deming, Victor Fung, Xiaojing Zhao, Jun Yuan, Tom Regier, Ali Aldalbahi, Zainab Almarhoon, Shaowei Chen, De-en Jiang, Nanfeng Zheng, Peng Zhang

    Bimetallic nanoparticles with tailored structures constitute a desirable model system for catalysts, as crucial factors such as geometric and electronic effects can be readily controlled by tailoring the structure and alloy bonding of the catalytic site. Here we report a facile colloidal method to prepare a series of platinum–gold (PtAu) nanoparticles with tailored surface structures and particle diameters on the order of 7 nm. Samples with low Pt content, particularly Pt4Au96, exhibited unprecedented electrocatalytic activity for the oxidation of formic acid. A high forward current density of 3.77 A mgPt−1 was observed for Pt4Au96, a value two orders of magnitude greater than those observed for core–shell structured Pt78Au22 and a commercial Pt nanocatalyst. Extensive structural characterization and theoretical density functional theory simulations of the best-performing catalysts revealed densely packed single-atom Pt surface sites surrounded by Au atoms, which suggests that their superior catalytic activity and selectivity could be attributed to the unique structural and alloy-bonding properties of these single-atomic-site catalysts.

    更新日期:2018-09-25
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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