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Fractal Design of Hierarchical PtPd with Enhanced Exposed Surface Atoms for Highly Catalytic Activity and Stability

Nano letters 2023年第16期23卷 7371-7378页

作者： Jie Ying Yuxuan Xiao Jiangbo Chen Zhi-Yi Hu Ge Tian Gustaaf Van Tendeloo Yuexing Zhang Mark D Symes Christoph Janiak Xiao-Yu Yang School of Chemical Engineering and Technology Sun Yat-sen University Zhuhai 519082 China. State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China. EMAT (Electron Microscopy for Materials Science) University of Antwerp Groenenborgerlaan 171 B-2020 Antwerpen Belgium. College of Chemistry and Chemical Engineering Hubei University Wuhan 430062 China. WestCHEM School of Chemistry University of Glasgow University Avenue Glasgow G12 8QQ U.K. Institut für Anorganische Chemie und Strukturchemie Heinrich-Heine-Universität Düsseldorf 40204 Düsseldorf Germany. School of Engineering and Applied Sciences Harvard University Cambridge Massachusetts 02138 United States.

Hierarchical assembly of arc-like fractal nanostructures not only has its unique self-similarity feature for stability enhancement but also possesses the structural advantages of highly exposed surface-active sites for activity enhancement, remaining a great challenge for high-performance metallic nanocatalyst design. Herein, we report a facile strategy to synthesize a novel arc-like hierarchical fractal structure of PtPd bimetallic nanoparticles (h-PtPd) by using pyridinium-type ionic liquids as the structure-directing agent. Growth mechanisms of the arc-like nanostructured PtPd nanoparticles have been fully studied, and precise control of the particle sizes and pore sizes has been achieved. Due to the structural features, such as size control by self-similarity growth of subunits, structural stability by nanofusion of subunits, and increased numbers of exposed active atoms by the curved homoepitaxial growth, h-PtPd displays outstanding electrocatalytic activity toward oxygen reduction reaction and excellent stability during hydrothermal treatment and catalytic process.

关键词： PtPd nanoalloys arc-like nanostructures directional catalysis fractal design hierarchical structures

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Magnetically Induced Anisotropic Conductive Hydrogels for Multidimensional Strain Sensing and Magnetothermal Physiotherapy

SSRN

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SSRN 2023年

作者： Zhang, Xuehui Lang, Bo Yu, Wenwen Jia, Lan Zhu, Fengbo Xue, Yanru Wu, Xiaogang Qin, Yixian Phil Chen, Weiyi Wang, Yanqin Zheng, Qiang College of Materials Science & Engineering Taiyuan University of Technology Taiyuan030024 China College of Biomedical Engineering Taiyuan University of Technology Taiyuan030024 China Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering Taiyuan030024 China Dept. of Biomedical Engineering State University of New York at Stony Brook New York11794 United States Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University Hangzhou310027 China

The development of flexible strain sensors with multidimensional sensing and physiotherapy abilities simultaneously is brilliant for the advancement of wearable sensing electronics. Herein, a composite hydrogel with anisotropic electromechanical properties and excellent magnetothermal capabilities was developed based on a magnetic field pre-induction strategy. Specifically, the as-developed two-dimensional Fe3O4@MXene nanohybrids were induced to be orientationally aligned within the polyvinyl alcohol (PVA) network for conductive hydrogels with anisotropic topology structures. Due to the as-optimized composite hydrogel exhibiting different conductivities in parallel and vertical directions, it can be developed into a multidimensional strain sensor, which is suitable for strain sensing in orthogonal directions with distinguishable gauge factors (such as GF = 3.20, while GF⊥ = 1.78 in the tensile strain range of 0 ~ 60%) and relatively fast response time (t = 74.47 ms, t⊥ = 157.63 ms). Furthermore, the composite conductive hydrogels can also be assembled into a 3D distribution array for detecting the magnitude and spatial distribution of stress. In addition, it also exhibits excellent magnetothermal physiotherapy capabilities. In summary, it is a promising candidate for next-generation multidimensional flexible sensors with rehabilitation assistant functions. © 2023, The Authors. All rights reserved.

关键词： Hydrogels

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电子束定向能量沉积中垂滴振荡的产生与抑制（英文）

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Engineering 2024年第6期 215-229页

作者： Zhiyue Liang Zhenyu Liao Haoyu Zhang Zixiang Li Li Wang Baohua Chang Dong Du Department of Mechanical Engineering Tsinghua University Key Laboratory for Advanced Materials Processing Technology Ministry of Education Tsinghua University

Electron beam–directed energy deposition(EB–DED) has emerged as a promising wire-based metal additive manufacturing technique. However, the effects of EBs on pendant droplets at wire tips have not yet been determined. The aim of this study is to enhance the understanding of this action by analyzing the mechanism of droplet oscillation. The pendant droplet oscillation phenomenon hinders the stable transfer of droplets to the molten pool and limits the feasibility of manufacturing complex lattice structures by EB–DED. Hence, another aim of this study is to create an oscillation suppression method. An escalating asymmetric amplitude is the main characteristic of droplet oscillation. The primary oscillationinducing force is the recoil force generated from the EB-acted local surface of the droplet. The physical mechanism of this force is the rapid increase and uneven distribution of the local surface temperature caused by the partial action of the EB. The prerequisites for droplet oscillation include vacuum conditions,high power densities, and bypass wire feeding processes. The proposed EB–dynamic surrounding melting(DSM) method can be applied to conveniently and effectively suppress oscillations, enable the accurate transfer of droplets to the molten pool, and achieve stable processes for preparing the strut elements of lattice structures. Lowering the temperature and improving the uniformity of its distribution are the mechanisms of oscillation suppression in EB–DSM. In this study, the physical basis for interpreting the mechanism by which EBs act on droplets and the technical basis for using EB–DED to prepare complex lattice structure parts are provided.

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Chemical/Light‐Powered Hybrid Micromotors with “On‐the‐Fly” Optical Brakes

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Angewandte Chemie 2018年第27期130卷

作者： Chuanrui Chen Songsong Tang Hazhir Teymourian Emil Karshalev Fangyu Zhang Jinxing Li Fangzhi Mou Yuyan Liang Jianguo Guan Joseph Wang Department of Nanoengineering University of California San Diego La Jolla CA 92093 USA State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 P. R. China

Hybrid micromotors capable of both chemically powered propulsion and fuel‐free light‐driven actuation and offering built‐in optical brakes for chemical propulsion are described. The new hybrid micromotors are designed by combining photocatalytic TiO 2 and catalytic Pt surfaces into a Janus microparticle. The chemical reactions on the different surfaces of the Janus particle hybrid micromotor can be tailored by using chemical or light stimuli that generate counteracting propulsion forces on the catalytic Pt and photocatalytic TiO 2 sides. Such modulation of the surface chemistry on a single micromotor leads to switchable propulsion modes and reversal of the direction of motion that reflect the tuning of the local ion concentration and hence the dominant propulsion force. An intermediate Au layer (under the Pt surface) plays an important role in determining the propulsion mechanism and operation of the hybrid motor. The built‐in optical braking system allows “on‐the‐fly” control of the chemical propulsion through a photocatalytic reaction on the TiO 2 side to counterbalance the chemical propulsion force generated on the Pt side. The adaptive dual operation of these chemical/light hybrid micromotors, associated with such control of the surface chemistry, holds considerable promise for designing smart nanomachines that autonomously reconfigure their propulsion mode for various on‐demand operations.

关键词： Chemischer Antrieb Janus-Mikromotoren Optische Bremsen Photokatalytische Reaktionen

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High-Performance Triboelectric–Electromagnetic Hybrid Nanogenerator Using Dual-Functional Flexible Neodymium Iron Boron/Ethyl Cellulose (Ndfeb/Ec) Composite Films for Wind Energy Scavenging

SSRN

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SSRN 2024年

作者： Zhao, Kun Song, Zhenhua Gao, Zongqiang Gao, Wei Liu, Ming-Jin Gu, Bingni Guo, Junhong Chueh, Yu-Lun State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals Lanzhou University of Technology Gansu Lanzhou730050 China School of Petrochemical Technology Lanzhou University of Technology Gansu Lanzhou730050 China School of Science Lanzhou University of Technology Gansu Lanzhou730050 China Department of Materials Science and Engineering National Tsing Hua University Hsinchu30013 Taiwan Colleage of Semiconductor Research National Tsing-Hua University Hsinchu30013 Taiwan Department of Materials Science and Engineering Korea University Seoul02841 Korea Republic of

Triboelectric–electromagnetic hybrid nanogenerator (HNG) with high output performance provides a very promising solution for realizing self-powered microelectronic devices. However, the complex structures and large mass of traditional HNGs make them difficult to prepare and carry. In this study, a rotating HNG based on flexible neodymium iron boron/ethyl cellulose (NdFeB/EC) composite films was designed for wind energy scavenging. A lightweight composite film with triboelectric and ferromagnetic properties, which can significantly reduce the weight of the rotor, was prepared to replace the magnet. Operated at a wind speed of 15.5 m/s, the triboelectric nanogenerator (TENG) unit of the optimized HNG with an interdigitated electrode gap of 2 mm can generate an open-circuit voltage (Voc) and a short-circuit current (Isc) of 55 V and 5.4 μA, respectively. The maximum power of TENG is 99.2 μW under the condition of an external load resistance of 10 MΩ. The corresponding electromagnetic generator (EMG) unit can produce Voc and Isc of approximately 0.16 V and 59.3 μA, delivering an output power of 2.5 μW at a matched loading resistance of 2.3 kΩ. Compared to the individual TENG or EMG units, the HNG exhibited better charging performance. A 470 μF capacitor can charge to 3.4 V within 600 s, and the stored energy can successfully power a commercial soil temperature–humidity meter to work continuously for 75 s and light 30 blue LEDs in parallel. This research is of great scientific significance for developing triboelectric–ferromagnetic dual-functional materials and designing highly integrated and lightweight HNGs. © 2024, The Authors. All rights reserved.

关键词： Nanogenerators

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Converse flexoelectricity around ferroelastic domain walls

arXiv

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arXiv 2019年

作者： Wang, Y.J. Tang, Y.L. Zhu, Y.L. Feng, Y.P. Ma, X.L. Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Wenhua Road 72 Shenyang110016 China University of Chinese Academy of Sciences Yuquan Road 19 Beijing100049 China State Key Lab of Advanced Processing and Recycling on Non-ferrous Metals Lanzhou University of Technology Langongping Road 287 Lanzhou730050 China

Domain walls (DWs) are ubiquitous in ferroelectric materials. Ferroelastic DWs refer to those who separate two domains with unparalleled polarizations (or two different ferroelastic variants). These ultrathin interfaces could be designed as minimized electronic devices1 since they possess fascinating functionalities, such as conductivity2, abnormal photovoltaic effect3, and so on. They are responsible to the enhancement of dielectric and piezoelectric properties of ferroelectric materials4,5. It is long believed that the structures of ferroelastic DWs can be simply explained from the perspective of mechanical and electric compatibilities in the framework of the Landau-Ginzburg-Devonshire (LGD) theory. Here we show that the converse flexoelectricity must be taken into account for fully describing the nature of ferroelastic DWs. The converse flexoelectricity is a stress or a strain induced by polarization gradients6, which is complementary to the relatively well-known direct flexoelectricity (the polarization induced by strain gradients)7. In our work, an unexpected asymmetric structure is identified, which is beyond the prediction of the conventional LGD theory. By incorporating the converse flexoelectricity into the LGD theory and using it to analyze high-resolution images acquired by the aberration-corrected transmission electron microscope (TEM), we demonstrate that it is the converse flexoelectricity that result in the asymmetric structure. Moreover, the flexoelectric coefficient is derived bquantifying the converse flexoelectricity around the DWs. This quantification is deterministic in both the magnitude and sign of flexoelectric coefficients, by the mutual verification of atomic mapping and first-principles calculations. Our results suggest that the converse flexoelectricity cannot be neglected for understanding the ferroelastic DWs and other boundaries in ferroelectric materials. Copyright © 2019, The Authors. All rights reserved.

关键词： Ferroelectric materials

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Angle-resolved photoemission spectroscopy study of HgBa2CuO4+δ

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Physical Review B 2014年第19期89卷 195141-195141页

作者： I. M. Vishik N. Barišić M. K. Chan Y. Li D. D. Xia G. Yu X. Zhao W. S. Lee W. Meevasana T. P. Devereaux M. Greven Z.-X. Shen Massachusetts Institute of Technology Department of Physics Cambridge Massachusetts 02139 USA University of Minnesota School of Physics and Astronomy Minneapolis Minnesota 55455 USA Institute of Solid State Physics Vienna University of Technology Vienna 1040 Austria Peking University International Center for Quantum Materials School of Physics Beijing 100871 China Collaborative Innovation Center of Quantum Matter Beijing 100871 China State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 China Stanford Institute for Materials and Energy Sciences SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo Park California 94025 USA Geballe Laboratory for Advanced Materials Departments of Physics and Applied Physics Stanford University Stanford California 94305 USA School of Physics Suranaree University of Technology Muang Nakhon Ratchasima 30000 Thailand

HgBa2CuO4+δ (Hg1201) has been shown to be a model cuprate for scattering, optical, and transport experiments, but angle-resolved photoemission spectroscopy (ARPES) data are still lacking owing to the absence of a charge-neutral cleavage plane. We report on progress in achieving the experimental conditions for which quasiparticles can be observed in the near-nodal region of the Fermi surface. The d-wave superconducting gap in near-optimally-doped Hg1201 is found to have a maximum of 39 meV. At low temperature, a kink is detected in the nodal dispersion at approximately 51 meV below the Fermi level, an energy that is different from other cuprates with comparable Tc. The superconducting gap, Fermi surface, and nodal band renormalization measured here provide a crucial momentum-space complement to other experimental probes.

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Operation characteristic of proton exchange membrane fuel cell under medium-pressure

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Huagong Xuebao/CIESC Journal 2012年第SUPPL.1期63卷 204-207页

作者： Liu, Jing Wan, Zhongmin Wan, Junhua Ding, Gangqiang Tu, Zhengkai Liu, Wei School of Information Engineering Hunan Institute of Science and Technology Yueyang 414006 Hunan China College of Chemistry and Chemical Engineering Huazhong University of Science and Technology Wuhan 430074 Hubei China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 Hubei China College of Energy and Power Engineering Huazhong University of Science and Technology Wuhan 430074 Hubei China

The operation characteristics of proton exchange membrane fuel cells with the channel width of 1mm and 2 mm under a medium-pressure are addressed, and the effect of temperature on the operation characteristic is investigated in detail. The results show that fuel cell with a 2 mm channel width can realize the long time operation in a closed-ended situation. The voltage of the 1mm width cell can drop from 0.7 V to 0.5 V in 3 min, while the 2 mm width cell can last for more than 53 min. Moreover, the temperature has a significant effect on the performance, the voltage of the 1 mm width cell can drop from 0.69 V to 0.5 V in less than 1.7 min. The resistance of the cell is increasing with the temperature, but the amplitude is smaller in high temperature.

关键词： Oxygen

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Hybridizing Engineering Strategy of Decatungstate Iii: Transition Metal Modified Carbon Quantum Dot-Regulated Photo-Catalytic Oxidation Performance of Decatungstate

SSRN

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SSRN 2024年

作者： Su, Anqun Jiang, Dabo Hu, Wenwei Liang, Shuting Yu, Kai Zhou, Weijie Wang, Jing Fu, Zaihui Liu, Yachun Liu, Jianxin Hunan University of Medicine Huaihua418000 China National & Local United Engineering Laboratory for New Petrochemical Materials & Fine Utilization of Resources Key Laboratory of Resource Fine-Processing and Advanced Materials of Hunan Province Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research Ministry of Education of China College of Chemistry and Chemical Engineering Hunan Normal University Changsha410081 China Chongqing Key Laboratory for Resource Utilization of Heavy Metal Wastewater Aquatic Ecosystems in the Three Gorges Reservoir Region of Chongqing Observation and Research Station Chongqing University of Arts and Sciences Yongchuan402160 China Hunan Chemical Vocational Technology College Zhuzhou412000 China

This paper discloses an efficient hybridizing engineering (HE) strategy of decatungstate (DT) with 3d transition metal ions (Mn+=Ni2+, Co2+ or Cu2+)-modified carbon quantum dots (Mn+/CQDs) as the dopants. Compared to pure CQD, The Mn+-cationized CQD can more efficiently combine with DT anion to fabricate high-quality hybrid via electrostatic interactions, thereby enhancing the visible light response of the hybrid and especially the separation efficiency of its photo-generated charge pairs. By varying the modified metal ions in Mn+/CQDs from Cu2+, Co2+ to Ni2+, the aforementioned hybridization effects can be fine-tuned and gradually enhanced, which are further improved in the presence of strongly acidic additives. Correspondingly, the photo-catalytic efficiency of the hybrid in the visible light-triggered selective oxidation of ethylbenzene with dioxygens in acetonitrile is continuously and significantly improved as the change of its metal ion from Cu2+, Co2+ to Ni2+, The best Ni2+/CQD-DT can achieve ca. 48% ethylbenzene conversion and 87.6% acetophenone selectivity in the presence of 2 M HCl. and also shows a much higher photo-catalytic activity for the photo-oxidation of toluene, cyclohexane and benzyl alcohol compared to pure DT. The HE strategy with Mn+/CQDs as the cationized hybridizers is much superior to that with pure CQD or Ni2+ as the hybridizer in hoisting the photo-catalytic performance of DT. © 2024, The Authors. All rights reserved.

关键词： Ethylbenzene

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Expansion of Multifunctionality of Non-Stoichiometric Manganite Ceramics Owing to Post-Annealing: Effect of High Pressure and Electrochemical Studies

SSRN

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SSRN 2022年

作者： Gong, Zhiwei Xu, Wei Liedienov, N.A. Butenko, D.S. Zatovsky, I.V. Wei, Ziyu Li, Quanjun Liu, Bingbing Pashchenko, A.V. Levchenko, G.G. State Key Laboratory of Superhard Materials International Center of Future Science Jilin University Changchun130012 China State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun130012 China Donetsk Institute for Physics and Engineering named after O.O. Galkin NASU Kyiv03028 Ukraine Shenzhen Key Laboratory of Solid State Batteries Academy for Advanced Interdisciplinary Studies Southern University of Science and Technology Shenzhen518055 China Guangdong Provincial Key Laboratory of Energy Materials for Electric Power Southern University of Science and Technology Shenzhen518055 China College of Physics Jilin University Changchun130012 China F.D. Ovcharenko Institute of Biocolloidal Chemistry NASU Kyiv03142 Ukraine Institute of Magnetism NASU and MESU Kyiv03142 Ukraine

Prospects for the use of manganites in various areas of modern technologies require comprehensive studies of their physical and chemical properties. La 0.9 Mn 1.1 O 3 (LMO) ceramics were synthesized at annealing temperature t ann = 1150 ℃ with further post-annealing at 1250, 1350, and 1450 ℃. They have been studied comprehensively using XRD, SEM, EDS, thermogravimetric, magnetic under high pressure, and electrochemical methods. As the t ann increases, the crystal structure symmetry changes from the rhombohedral R -3 c to the monoclinic P 21/ c type, the crystallite size and concentration of chemical defects increase, and the tolerance factor reduces. The post-annealing, on one hand, leads to a dramatic reduction of the magnetic entropy change –Δ S M max from 3.50 to 0.75 J/(kg⋅K) under 2 T and Curie temperature T C from 227 to 113 K with an increase in the t ann . This is due to the weakening of both the double-exchange (DE) and multiple DE interactions by the increased content of chemical defects. On the other hand, an external hydrostatic pressure works oppositely enhancing DE interactions and reducing the disorder. The saturation of the –Δ S M max and T C is achieved already at around 0.4 GPa. The LMO-1150 exhibits the best magnetocaloric characteristics to compare with other studied samples. Moreover, the electrochemical characteristics of the LMO materials as electrocatalysts for overall water splitting (OER process) and features of their transformation in different 0.5 M K 2 SO 4 , 0.5 M K 2 HPO 4 , and 0.1 M K 2 B 4 O 7 electrolytes have been studied thoroughly. After electrocatalysis, the magnetization M decreases and the T C remains the same indicating the persistence of the DE. All samples show the best electrochemical performance in the 0.5 M K 2 HPO 4 media. The obtained results demonstrate the ways for controlling magnetocaloric parameters of the LMO ceramics at changing the internal and external conditions, as well as an evaluation of the possibilities

关键词： Annealing

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