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Mitigating oxygen reduction reaction barriers: An in-depth first-principles exploration of high-entropy alloy as catalysts

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Electrochemistry Communications 2024年 166卷

作者： Chen, Ming-Yi Thanh Thuy Tran, Ngoc Hsu, Wen-Dung Department of Materials Science and Engineering National Cheng Kung University 1 University Road Tainan701 Taiwan Research Center National Cheng Kung University Tainan701 Taiwan Program on Semiconductor Packaging and Testing Academy of Innovative Semiconductor and Sustainable Manufacture National Cheng Kung University Tainan701 Taiwan

This study investigates the effectiveness of high-entropy alloys (HEAs) as catalysts for reducing the energy barrier of the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). Four HEAs—IrPdPtRh, CoCrFeNi, NbMoTaW, and TiZrNbTa—are analyzed as potential catalysts. This superiority arises from the shift in the overall d-band center position towards negative energy in HEAs. The study suggests that an increased standard deviation of atomic valences within HEAs correlates positively with improved ORR efficiency, indicating it as a potential design indicator for cost-effective catalysts. Moreover, predictions of valence variations based on differences in electronegativity between individual elements are proposed. Additionally, the research highlights that additional surface adsorption of Pt on HEAs would further enhance ORR activity. © 2024

关键词： Catalysts

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Long-Term Stability of NaOCl Passivation on CZTS Crystals Investigated via SEM-EDS

Long-Term Stability of NaOCl Passivation on CZTS Crystals In...

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IEEE Symposium on Nuclear science (NSS/MIC)

作者： J. Seo J. Byun K. Kim Y. Kim B. Park Department of Health and Safety Convergence Science Korea University Seoul Republic of Korea Interdisciplinary program in precision public health Korea University Seoul Republic of Korea Department of Materials Science and Engineering Korea University Seoul Republic of Korea School of Health and Environmental Science Korea University Seoul Republic of Korea Marine Radioactivity Monitoring Group Korea University Busan Republic of Korea

ISBN: (数字)9798350388152

ISBN: (纸本)9798350388169

This study investigates the efficient passivation of CdTe-based semiconductor crystals, focusing on the long-term stability and underlying mechanisms of NaOCl passivation. CdZnTeSe crystals were grown, processed, and passivated with NaOCl, and their surface characteristics were studied using SEM-EDS and XPS. The passivation was found to significantly enhance the surface resistance, with a sustained effect for more than 90 s, attributed to the formation of a tellurium oxide layer. The passivation process was further elucidated through detailed morphological and compositional analyses. The NaOCl-passivated crystals exhibited improved electrical and spectroscopic properties in radiation detection, with a prolonged stability of 60-90 days, which are longer compared to other passivants. Additionally, the feasibility of NaOCl passivation on a CdZnTeSe detector was explored, showcasing enhanced resistivity and spectroscopic performance. The study concludes with insights into the potential industrial application of NaOCl passivation for CdTe-based radiation detectors.

关键词： Microwave integrated circuits Semiconductor detectors Surface resistance Radiation detectors Surface morphology Crystals Stability analysis

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Coherent X-ray Spectroscopy Elucidates Nanoscale Dynamics of Plasma-Enhanced Thin-Film Growth

arXiv

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arXiv 2023年

作者： Myint, Peco Woodward, Jeffrey M. Wang, Chenyu Zhang, Xiaozhi Wiegart, Lutz Fluerasu, Andrei Headrick, Randall L. Eddy, Charles R. Ludwig, Karl F. Department of Physics Division of Materials Science and Engineering Boston University BostonMA United States Electronics Science and Technology Division U.S. Naval Research Laboratory WashingtonDC United States Department of Physics and Materials Science Program University of Vermont Burlington United States National Synchrotron Light Source II Brookhaven National Laboratory Upton United States

Sophisticated thin film growth techniques increasingly rely on the addition of a plasma component to open or widen a processing window, particularly at low temperatures. However, the addition of the plasma into the growth environment also complicates the surface dynamical evolution. Taking advantage of continued increases in accelerator-based X-ray source brilliance, this real-time study uses X-ray Photon Correlation Spectroscopy (XPCS) to elucidate the nanoscale surface dynamics during Plasma-Enhanced Atomic Layer Deposition (PE-ALD) of an epitaxial indium nitride film. XPCS examines the evolution of the coherent X-ray scattering speckle pattern, which is a fingerprint of the unique sample microstructure at each moment in time. In PE-ALD, ultrathin films are synthesized from repeated cycles of alternating self-limited surface reactions induced by temporally-separated pulses of material precursor and plasma reactant, allowing the influence of each on the evolving morphology to be examined. During the heteroepitaxial 3D growth examined here, sudden changes in surface structure during initial film growth, consistent with numerous overlapping stress-relief events, are observed. When the film becomes continuous, the nanoscale surface morphology abruptly becomes long-lived with correlation time spanning the period of the experiment. Throughout the growth experiment, there is a consistent repeating pattern of correlations associated with the cyclic growth process, which is modeled as transitions between different surface states. The plasma exposure does not simply freeze in a structure that is then built upon in subsequent cycles, but rather there is considerable surface evolution during all phases of the growth cycle. © 2023, CC BY.

关键词： Ultrathin films

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Ultra-Cold Cryogenic TEM with Liquid Helium and High Stability

arXiv

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arXiv 2024年

作者： Rennich, Emily Sung, Suk Hyun Agarwal, Nishkarsh Gates, Maya Kerns, Robert Hovden, Robert Baggari, Ismail El The Rowland Institute at Harvard Harvard University CambridgeMA02142 United States Department of Mechanical Engineering University of Michigan Ann ArborMI48109 United States Department of Materials Science and Engineering University of Michigan Ann ArborMI48109 United States Michigan Center for Materials Char-acterization University of Michigan Ann ArborMI48109 United States Applied Physics Program University of Michigan Ann ArborMI48109 United States

Cryogenic transmission electron microscopy has revolutionized structural biology and materials science, but achieving temperatures below the boiling point of liquid nitrogen remains a long-standing aspiration. We introduce an ultra-cold liquid helium transmission electron microscope specimen holder, featuring continuous cryogen flow and vibration decoupling. This instrument is compatible with modern aberration-corrected microscopes and achieves sub-25 K base temperature, ±2 mK thermal stability over many hours, and atomic resolution—setting the stage for a new era of cryogenic electron microscopy. © 2024, CC BY.

关键词： High resolution transmission electron microscopy

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Enhancing oxygen reduction reaction with Pt-decorated Cu@Pd and high-entropy alloy catalysts: Insights from first-principles analysis of Pt arrangement

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Applied Catalysis A: General 2024年 669卷

作者： Chen, Ming-Yi Tran, Ngoc Thanh Thuy Alao, Ahmed Abubakar Hsu, Wen-Dung Department of Materials Science and Engineering National Cheng Kung University 1 University Road Tainan701 Taiwan Research Center National Cheng Kung University Tainan701 Taiwan Program on Semiconductor Packaging and Testing Academy of Innovative semiconductor and Sustainable Manufacture National Cheng Kung University Tainan701 Taiwan

The efficiency of oxygen reduction reaction (ORR) in the proton-exchange membrane fuel cells (PEMFCs) heavily relies on the surface Pt atom arrangement, which can be represented by the Pt-Pt average distance. Here, we employed density functional theory (DFT) to examine the influence of Pt arrangement on the ORR efficiency of Cu@Pd core-shell and high-entropy alloy catalysts. Our DFT calculations reveal that a shorter Pt-Pt average distance on the surface leads to a lower O2 dissociation barrier. Nevertheless, a shorter Pt-Pt average distance is not thermodynamically favored for the Cu@Pt catalyst. Moreover, we discovered a robust correlation between the level of the d-band center of the catalyst and the O2 adsorption energy. To explore the potential of controlling Pt arrangement, we investigated the use of NbMoTaW high-entropy alloy (HEA) substrates. Our findings suggest that HEA substrates provide promising surface chemistry for tuning Pt arrangement and controlling the O2 dissociation barrier. © 2023

关键词： Oxygen

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Comparison of CMAS corrosion and sintering induced microstructural characteristics of APS thermal barrier coatings

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Journal of materials science & Technology 2019年第3期35卷 440-447页

作者： Yiyou Wu Hua Luo Canying Cai Yanguo Wang Yichun Zhou Li Yang Guangwen Zhou School of Materials Science and Engineering Xiangtan University Key Laboratory of Low Dimensional Materials & Application Technology of Ministry of Education Xiangtan University Department of Mechanical Engineering & Materials Science and Engineering Program State University of New York at Binghamton

The microstructural features of high-temperature sintered and CaO-MgO-Al_2O_3-SiO_2(CMAS) corroded air plasma sprayed Y_2O_3 stabilized ZrO_2(YSZ) thermal barrier coatings(TBCs) under the thermal gradient condition were comparatively studied. As-sprayed YSZ has a lamellar structure and the lamellae are composed of closely aligned columnar crystals. The sintered and the CMAS corroded YSZ coatings maintain the t'-ZrO_2 phase as the as-sprayed YSZ coating. The sintered YSZ remains the lamellar structure with reduced interlamellar gaps and grains coarsening. After the CMAS corrosion, the top layer of the YSZ coating keeps its lamellar structure consisting of some columnar grains with the CMAS infiltration into the intergrain gaps and the formation of striped Zr_2Y_2 O_7. The typical lamellar structure transforms into more equiaxed grains in the middle and bottom layers of the ceramic coating along with significant infiltration of amorphous CMAS and anorthite formation in the bottom layer owing to the high contents of Ca and Al.

关键词： YSZ thermal barrier coating APS CMAS corrosion Anorthite

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Gradient Design with Low-Tortuosity Overcoming Kinetic Limitations in High-Loading Solid-State Cathodes

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Angewandte Chemie 2025年

作者： Guangzeng Cheng Jinping Yu Yonghui Wang Zhengyu Ju Yue Zhu Weiqian Tian Jingwei Chen Huanlei Wang Jingyi Wu Guihua Yu School of Materials Science and Engineering Ocean University of China Qingdao 266404 China Materials Science and Engineering Program and Walker Department of Mechanical Engineering The University of Texas at Austin Austin Texas 78712 USA

The extensive commercialization of practical solid-state batteries (SSBs) necessitates the development of high-loading solid-state cathodes with fast charging capability. However, electrochemical kinetics are severely delayed in thick cathodes due to tortuous ion transport pathways and slow solid-solid ion diffusion, which limit the achievable capacity of SSBs at high current densities. In this work, we propose a conductivity gradient cathode with low-tortuosity to enable facile ion transport and counterbalance ion concentration gradient, thereby overcoming the kinetic limitations and achieving fast charging capabilities in thick cathodes. The LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathodes deliver a room-temperature (RT) capacities of 147 and 110 mAh g −1 at 5 C and 10 C, respectively, and meanwhile achieve a RT areal capacity of 3.3 mAh cm −2 at 3 C, enabling SSBs simultaneously high energy and power densities. The universality of this strategy is demonstrated in LiFePO 4 cathodes, providing a novel solution for fast charging and large-scale application of high-loading SSBs.

关键词： solid-state battery composite cathode high-loading gradient low-tortuosity

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Velocity-gauge Real-time Time-dependent Density Functional Tight-binding for Large-scale Condensed Matter Systems

arXiv

引用

arXiv 2023年

作者： Xu, Qiang Del Ben, Mauro Okyay, Mahmut Sait Choi, Min Ibrahim, Khaled Z. Wong, Bryan M. Materials Science & Engineering Program Department of Chemistry Department of Physics & Astronomy University of California-Riverside RiversideCA92521 United States Applied Mathematics & Computational Research Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States

We present a new velocity-gauge real-time, time-dependent density functional tight-binding (VG-rtTDDFTB) implementation in the open-source DFTB+ software package (https://***) for probing electronic excitations in large, condensed matter systems. Our VG-rtTDDFTB approach enables real-time electron dynamics simulations of large, periodic, condensed matter systems containing thousands of atoms with a favorable computational scaling as a function of system size. We provide computational details and benchmark calculations to demonstrate its accuracy and computational parallelizability on a variety of large material systems. As a representative example, we calculate laser-induced electron dynamics in a 512-atom amorphous silicon supercell to highlight the large periodic systems that can be examined with our implementation. Taken together, our VG-rtTDDFTB approach enables new electron dynamics simulations of complex systems that require large periodic supercells, such as crystal defects, complex surfaces, nanowires, and amorphous materials. Copyright © 2023, The Authors. All rights reserved.

关键词： Gages

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Terahertz phonon polariton concentrator based on perovskite oxides

Terahertz phonon polariton concentrator based on perovskite ...

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Conference on Lasers and Electro-Optics (CLEO)

作者： Rui Xu Tong Lin Jiaming Luo Xiaotong Chen Elizabeth R. Blackert Alyssa R. Moon Khalil M. JeBailey Hanyu Zhu Department of Materials Science and Nano Engineering Rice University Houston U.S.A. Applied Physics Graduate Program Rice University Houston U.S.A. Nanotechnology Research Experience for Undergraduates (Nano REU) Program Rice University Houston U.S.A.

We report the experimental demonstration of surface phonon-polaritonic devices in a broad spectral range of 7-13 THz based on SrTiO 3 . We designed planar ultrafast concentrators that amplifies transient electric fiel... 详细信息

ISBN: (纸本)9781957171258

关键词： Concentrators Electric fields Fast Fourier transforms Field enhancement Fused silica Second harmonic generation

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Revolutionary Energy Harvesting: Gravity-Driven Piezocatalysts for Sustainable Hydrogen Production in MoS2@Mo2CTx Systems

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Advanced Energy materials 2024年第39期14卷

作者： Lin, Hsun-Yen Wu, Jyh Ming Department of Materials Science and Engineering National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan Ph.D Program in Prospective Functional Materials Industry National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan High Entropy Materials Center National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan

Hydrogen (H2) is mainly produced using steam methane reforming, electrolysis, and gasification, which require external energy and special catalysts. A new catalyst by combining MoS2 nanoflowers (NFs) with metal carbide/nitride nanosheets (Mo2CTx MXene) to create a nanosheet bending moment. The MoS2@Mo2CTx heterostructures achieve a production rate of 1164.8 µmol g−1 h−1 under an application of mechanical force, 4.01 and 3.06 times higher than Mo2CTx and MoS2 alone, due to enhanced charge transfer from MoS2's piezoelectricity and Mo2CTx's conductivity. This study introduces a pioneering methodology that harnesses gravitational energy as a continuous mechanical force, simulated using a peristaltic pump, to drive the piezocatalytic hydrogen evolution reaction (HER), achieving a notable hydrogen production rate of 454.1 µmol g−1 over 24 hours and demonstrating a sustained capability for hydrogen generation. The theoretical calculation results validate the piezoelectric potential in water-flow-pressure triggered HER systems. The piezocatalytic HER system, assuming powered by the Hoover Dam, will produce 290.9 kmoles of hydrogen per ton daily, equivalent to utilizing 19 150 kWh of energy in the electrocatalytic system. The simulated gravity-driven water flow using MoS2@Mo2CTx piezocatalysts for H2 generation demonstrates superior efficiency by eliminating common thermal energy conversion losses, marking a significant breakthrough in sustainable hydrogen production technologies. © 2024 Wiley-VCH GmbH.

关键词： Molybdenum compounds

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