检索结果-内蒙古大学图书馆

SSRN 2023年

作者： Li, Ling Zhao, Guoyan Lv, Zhengang An, Pengfei Ao, Jingyan Song, Mingxia Zhao, Jiankang Liu, Guozhu Key Laboratory for Green Chemical Technology of Ministry of Education School of Chemical Engineering and Technology Tianjin University Tianjin300072 China National Energy Center for Coal to Liquids Synfuels China Technology Co. Ltd Beijing101400 China State Key Laboratory of Coal Conversion Institute of Coal Chemistry Chinese Academy of Sciences Taiyuan030001 China Beijing Synchrotron Radiation Facility Institute of High Energy Physics Beijing100049 China University of Chinese Academy of Sciences Beijing100049 China Hefei National Research Center for Physical Sciences at the Microscale University of Science and Technology of China Anhui Hefei230026 China

Bimetallic NiPt catalysts with virtue of synergy characters have gained prominence in steam reforming (SR). However, modulation of the localized coordination environment in synergistic Ni-Pt catalysts towards highly efficient SR is still a challenge. Herein, coordination-induced Ni-Pt synergy difference in bimetallic NiPt/Al2O3 catalysts through precursor control method was investigated in converting n-dodecane SR to hydrogen. The H2 formation rate showed a volcano-shape dependence on Pt-Pt coordination number (CN), and the optimal NiPt-Cl/Al2O3 catalyst exhibits a H2 formation rate enhanced up to 3.5 folds compared with monometallic catalysts. Furthermore, temperature-programmed surface reaction unveiled that NiPt-Cl/Al2O3 with Pt-Pt CN around 2 (or 2.5) remarkably promoted CHx and O/OH species formation. Additionally, density functional theory calculations indicated Pt-Pt CN around 2 prominently lowered the activation barriers of the crucial elementary of CHx species oxidation, resulting in an enhancement in n-dodecane SR activity and coking resistance. This unveils a novel principle of bimetallic synergy and provides new avenues for rationally designing catalysts in SR. © 2023, The Authors. All rights reserved.

关键词： Binary alloys

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Silicalite-1 zeolite encapsulated Pt nanoparticles via ligand-protected in-situ construction for boosting auto-exhaust carbon particle oxidation

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Nano Research 2025年第5期18卷 274-285页

作者： Li, Yuanfeng Qin, Tian Guo, Hao Wei, Yuechang Ma, Yaxiao Xu, Linsheng Cui, Baolong Xiong, Jing Zhang, Peng Liu, Xi Chen, Liwei Liu, Yunpeng Liu, Jian Zhao, Zhen State Key Laboratory of Heavy Oil Processing Key Laboratory of Optical Detection Technology for Oil and Gas College of Science China University of Petroleum Beijing102249 China School of Chemistry and Chemical Engineering Ningxia University Yinchuan750021 China School of Chemistry and Chemical In-situ Center for Physical Science Frontiers Science Centre for Transformative Molecules Shanghai Jiao Tong University Shanghai200240 China Multi-discipline Research Center Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China

The enhancement of activity and stability of noble metal-based catalysts for purification of auto-exhaust carbon particle (soot) oxidation remains a grand challenge under harsh reaction conditions. Herein, the encapsulated catalysts of platinum nanoparticles (NPs) confined in silicalite-1 (S-1) zeolite were prepared by the ligand-protected in-situ synthesis method. The Pt NPs (4 nm) are located within the intersectional channels between the straight and the sinusoidal 10-ring channels of rigid S-1 zeolite and well stabilize inside the S-1 via Pt–O–Si bonds. The Pt@S-1 catalyst (0.38 wt.% of Pt loading) exhibits excellent performance (T50 = 368 °C, T50 corresponds to the temperatures at which 50% of soot conversion occurs) compared with the conventional Pt/S-1 catalyst during soot oxidation. The Pt@S-1 catalyst displays high long-term catalytic stability after the hydrothermal aging at 800 °C for 10 h, and the deactivation rate of the Pt@S-1 catalyst is one-tenth that of the Pt/S-1 catalyst. In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT) calculations corroborated that the encapsulated Pt NPs in Pt@S-1 catalyst display a higher d-band center than the isolated Pt NPs, which enhances bonding strength for coadsorption of NO and O2 molecules. The steric hindrance effect promotes the desorption of the critical intermediate of NO2, which is the key step to the NO2-assistant catalytic mechanism for soot oxidation. The ligand-protected in-situ confinement synthesis of metal nanoparticle catalysts not only ensures high activity and stability but also paves the way for the development of effective catalysts for soot oxidation in practical applications. © The Author(s) 2025. Published by Tsinghua University Press.

关键词： Fourier transform infrared spectroscopy

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Room-temperature surface multiferroicity in Y2NiMnO6 nanorods

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physical Review B 2022年第23期105卷 235429-235429页

作者： Shubhankar Mishra Amritendu Roy Aditi Sahoo Biswarup Satpati Anirban Roychowdhury P. K. Mohanty Chandan Kumar Ghosh Dipten Bhattacharya School of Materials Science and Nanotechnology Jadavpur University Kolkata 700032 India School of Minerals Metallurgical and Materials Engineering Indian Institute of Technology Bhubaneswar 752050 India Advanced Materials and Chemical Characterization Division CSIR–Central Glass and Ceramic Research Institute Kolkata 700032 India Saha Institute of Nuclear Physics A CI of Homi Bhabha National Institute 1/AF Salt Lake Kolkata 700064 India Department of Physics Krishnath College Berhampore 742101 West Bengal India Department of Physical Sciences IISER Kolkata Mohanpur West Bengal 741246 India

We report observation of surface-defect-induced room-temperature multiferroicity—surface ferromagnetism (MS at 50 kOe ≈0.005 emu/g), ferroelectricity (PR≈2nC/cm2), and significantly large magnetoelectric coupling (decrease in PR by ≈80% under ≈15 kOe field)—in nanorods (diameter ≈100 nm) of double perovskite Y2NiMnO6 compound. In bulk form, this system exhibits multiferroicity only below its magnetic transition temperature TN≈ 70 K. On the other hand, the oxygen vacancies, formed at the surface region (thickness ≈10 nm) of the nanorods, yield long-range magnetic order as well as ferroelectricity via Dzyloshinskii-Moriya exchange coupling interactions with strong Rashba spin-orbit coupling. Sharp drop in PR under magnetic field indicates strong cross coupling between magnetism and ferroelectricity as well. Observation of room-temperature magnetoelectric coupling in nanoscale for a compound which, in bulk form, exhibits multiferroicity only below 70 K underscores an alternative pathway for inducing magnetoelectric multiferroicity via surface defects and, thus, in line with magnetoelectric property observed, for example, in domain walls or boundaries or interfaces of heteroepitaxially grown thin films which do not exhibit such features in their bulk.

关键词： Surface & interfacial phenomena Ferroelectrics Multiferroics Nanorods Magnetic force microscopy Monte Carlo methods

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Two-dimensional topological platinum telluride superstructures with periodic tellurium vacancies

arXiv

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arXiv 2023年

作者： Xu, Xin Wang, Xuechun Yu, Shuming Wang, Chenhui Liu, Guowei Li, Hao Yang, Jiangang Li, Jing Sun, Tao Hai, Xiao Li, Lei Liu, Xue Zhang, Ying Zhang, Weifeng Zhang, Quan Wang, Kedong Xu, Nan Ma, Yaping Ming, Fangfei Cui, Ping Lu, Jiong Zhang, Zhenyu Xiao, Xudong State Key Lab of Optoelectronic Materials and Technologies Guangdong Province Key Laboratory of Display Material and Technology School of Electronics and Information Technology Sun Yat-sen University Guangzhou510275 China School of Physical Science and Technology Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education Wuhan University Wuhan430072 China School of Future Technology Henan Key Laboratory of Quantum Materials and Quantum Energy Henan University Zhengzhou450046 China University of Science and Technology of China Hefei230026 China Institute for Advanced Studies Wuhan University Wuhan430072 China Department of Physics Southern University of Science and Technology Shenzhen518055 China Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education School of Chemistry Beihang University Beijing100191 China School of Chemical Engineering Xi'an Key Laboratory of Special Energy Materials Northwest University Xi’an710069 China Department of Chemistry National University of Singapore Singapore117543 Singapore Core Facility of Wuhan University Wuhan430072 China Anhui Key Laboratory of Magnetic Functional Materials and Devices Institute of Physical Science and Information Technology Anhui University Anhui Hefei230601 China Institute of Quantum Materials and Physics Henan Academy of Sciences Zhengzhou450046 China College of Chemistry and Chemical Engineering Hubei Normal University Huangshi435002 China

Defect engineering in the inherently inert basal planes of transition metal dichalcogenides (TMDs), involving the introduction of chalcogen vacancies, represents a pivotal approach to enhance catalytic activity by exposing high-density catalytic metal single-atom sites. However, achieving a single-atom limit spacing between chalcogen vacancies to form ordered superstructures remains challenging for creating uniformly distributed high-density metal single-atom sites on TMDs comparable to carbon-supported single-atom catalysts (SACs). Here we unveil an efficient TMD-based topological catalyst for hydrogen evolution reaction (HER), featuring high-density single-atom reactive centers on a few-layer (7×7)-PtTe2-x superstructure. Compared with pristine Pt(111), PtTe2, and (2×2)-PtTe2-x, (7×7)-PtTe2-x exhibits superior HER performance owing to its substantially increased density of undercoordinated Pt sites, alongside exceptional catalytic stability when operating at high current densities. First-principles calculations confirm that multiple types of undercoordinated Pt sites on (7×7)-PtTe2-x exhibit favorable hydrogen adsorption Gibbs free energies, and remain active upon increasing hydrogen coverage. Furthermore, (7×7)-PtTe2-x possesses nontrivial band topologies with robust edge states, suggesting potential enhancements for HER. Our findings open up a new avenue for the development of TMD-based catalysts and exciting prospects for the exploration of topological materials in catalysis and beyond. © 2023, CC BY.

关键词： Topology

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Estimating Trotter Approximation Errors to Optimize Hamiltonian Partitioning for Lower Eigenvalue Errors

arXiv

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arXiv 2023年

作者： Martínez-Martínez, Luis A. Kamath, Prathami Divakar Izmaylov, Artur F. Chemical Physics Theory Group Department of Chemistry University of Toronto TorontoONM5S 3H6 Canada Department of Physical and Environmental Sciences University of Toronto Scarborough TorontoONM1C 1A4 Canada Department of Metallurgical Engineering and Materials Science Indian Institute of Technology Maharashtra Bombay400076 India

One of the ways to encode many-body Hamiltonians on a quantum computer to obtain their eigen-energies through Quantum Phase Estimation is by means of the Trotter approximation. There were several ways proposed to assess the quality of this approximation based on estimating the norm of the difference between the exact and approximate evolution operators. Here, we would like to explore how these different error estimates are correlated with each other and whether they can be good predictors for the true Trotter approximation error in finding eigenvalues. For a set of small molecular systems we calculated the exact Trotter approximation errors of the first order Trotter formulas for the ground state electronic energies. Comparison of these errors with previously used upper bounds show almost no correlation over the systems and various Hamiltonian partitionings. On the other hand, building the Trotter approximation error estimation based on perturbation theory up to a second order in the time-step for eigenvalues provides estimates with very good correlations with the Trotter approximation errors. The developed perturbative estimates can be used for practical time-step and Hamiltonian partitioning selection protocols, which are paramount for an accurate assessment of resources needed for the estimation of energy eigenvalues under a target accuracy. © 2023, CC BY.

关键词： Hamiltonians

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Phase Transitions in Mixed-Dimensional Perovskite: From Film Formation Evolution to its Impact on Optoelectronic Properties

SSRN

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SSRN 2024年

作者： Xiang, Jin Wang, Fei Liang, Xiao Duan, Dawei Yuan, Mingjian Wu, Tom Hu, Hanlin Shi, Yumeng International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education Institute of Microscale Optoelectronics Shenzhen University Shenzhen518060 China Hoffmann Institute of Advanced Materials Shenzhen Polytechnic University Shenzhen518055 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing School of Materials Science and Engineering Wuhan University of Technology Wuhan430070 China College of Chemistry and Chemical Engineering Jishou University Hunan Jishou416000 China College of Chemistry Nankai University Tianjin300071 China Department of Applied Physics The Hong Kong Polytechnic University Kowloon999077 Hong Kong Key Laboratory of Luminescence and Optical Information Ministry of Education School of Physical Science and Engineering Beijing Jiaotong University Beijing100044 China

The integration of 2D/3D mixed-dimensional structures in perovskite solar cells (PSCs) has been demonstrated to substantially improve both their photovoltaic performance and device stability. However, the detailed formation mechanism of these mixed-dimensional perovskite phases remains largely unexplored. In this study, we investigate the in-depth formation evolution of mixed-dimensional perovskite phases using the pre-adding method under both one-step and two-step processing condition, where the HTAB ligand molecule is introduced into the perovskite precursor solution beforehand. In the two-step sequential deposition method, 2D perovskite phases formed sequentially via 2D-α/β/γ (upon the assistance of IPA solvent) → 2D-7.6° (upon thermal annealing) → 2D-7.3° (upon thermal annealing). Conversely, in the one-step method, a distinct progression is noted: 2D-7.6° (HTAB ligand react with intermediate phase) → 2D-7.3°. The 2D-α/β/γ phases exhibit extremely thin, belt-like crystals that cover the 3D perovskite surface, the 2D-7.6° phase trends to envelop the 3D perovskite grains without clear crystal morphology, while the 2D-7.3° phase forms distinct platelet-shaped crystals interspersed among the 3D perovskite grains. Leveraging the defect passivation properties of those mixed-dimensional perovskite phases, as well as improved film morphology and crystallinity adjusted by HTAB ligand, an external electroluminescence quantum efficiency (EQELED) of 13.5% is achieved in PSCs with a non-radiative voltage loss of just 52 mV, promoting the power conversion efficiency to 24.54%. This work offers the significant insights into the phase-transition of mixed-dimensional perovskite and their impact on the optoelectronic properties. © 2024, The Authors. All rights reserved.

关键词： Perovskite

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In Situ Regulating the Phase Structure of Ce-Based Catalytic Sites to Boost the Performance of Zinc-Air Batteries

SSRN

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SSRN 2024年

作者： Liu, Jianping Jin, Yuanlin Jin, Rong Liu, Yao Ma, Zili Guo, Chaozhong Lei, Yu Sun, Lingtao Chen, Haifeng Si, Yujun Li, Sha Li, Honglin Chongqing Key Laboratory of Materials Surface & Interface Science Chongqing University of Arts and Sciences Chongqing402160 China College of Optoelectronic Engineering Chongqing University Chongqing401331 China College of Materials Science and Engineering Kunming University of Science and Technology Kunming650093 China Institute of Chemical and Gas and Oil Technologies T.F. Gorbachev Kuzbass State Technical University Kemerovo650000 Russia Hefei National Research Center for Physical Sciences at the Microscale University of Science and Technology of China Hefei230026 China College of Chemistry and Chemical Engineering Chongqing University Chongqing401331 China College of Chemistry and Environmental Engineering Sichuan University of Science and Engineering Zigong643000 China Institute of Smart City and Intelligent Transportation Southwest Jiaotong University Chengdu611756 China College of Physics and Electronic Engineering Chongqing Normal University Chongqing401331 China

We report an iodide-induced phase-regulation strategy to in-situ synthesize a Ce-rich single-atom catalyst (SACs) with a high Ce loading (15.9 wt.%) and a uniform distribution of Ce-N4O2 sites on the curved surface of porous nanocarbon framework. The oxygen reduction reaction (ORR) mechanisms on the Ce-N4O2 SACs are recorded by in-situ Raman spectra. Moreover, the density functional theory (DFT) calculations show that the Ce-N4O2 structure can optimize the electronic configuration of Ce and positively promote the activation of adsorbates. As expected, this catalyst delivers excellent ORR electrocatalytic activity and stability (half-wave potential decay ~11 mV after cycling for 30k cycles). The assembled primary zinc-air battery demonstrates a remarkable energy density (ED) of 946 Wh kgZn-1 and exhibits predominant long-term durability (ED reduction ~3.5 % after for 130 h). This work shows that rare-earth SACs, subjected to a four-in-one regulation encompassing structure-density-configuration-mass transfer, hold great promise in realizing high ED metal-air batteries. © 2024, The Authors. All rights reserved.

关键词： Electrolytic reduction

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Structural Reinforcement in Mechanically Interlocked Two-Dimensional Polymers by Suppressing Interlayer Sliding

arXiv

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arXiv 2024年

作者： Yang, Ye Knapp, André Bodesheim, David Croy, Alexander Hambsch, Mike Naisa, Chandrasekhar Pohl, Darius Rellinghaus, Bernd Zhao, Changsheng Mannsfeld, Stefan C.B. Cuniberti, Gianaurelio Wang, Zhiyong Dong, Renhao Fery, Andreas Feng, Xinliang Center for Advancing Electronics Dresden Faculty of Chemistry and Food Chemistry Technische Universität Dresden Dresden Germany Institute of Physical Chemistry and Polymer Physics Leibniz Institute of Polymer Research Dresden Dresden Germany Institute for Materials Science Max Bergmann Center for Biomaterials TU Dresden Dresden Germany Institute of Physical Chemistry Friedrich Schiller University Jena Jena Germany Center for Advancing Electronics Dresden Faculty of Electrical and Computer Engineering Technische Universität Dresden Dresden Germany TUD Dresden University of Technology Dresden Germany College of Polymer Science and Engineering State Key Laboratory of Polymer Materials Engineering Sichuan University Chengdu China Germany Key Laboratory of Colloid and Interface Chemistry of the Ministry of Education School of Chemistry and Chemical Engineering Shandong University Jinan China TU Dresden Dresden Germany Chair for Physical Chemistry of Polymeric Materials Technical University Dresden Dresden Germany

Preserving the superior mechanical properties of monolayer two-dimensional (2D) materials when transitioning to bilayer and layer-stacked structures poses a great challenge, primarily arising from the weak van der Waals (vdW) forces that facilitate interlayer sliding and decoupling. Here, we discover that mechanically interlocked 2D polymers (2DPs) offer a means for structural reinforcement from monolayer to bilayer. Incorporating macrocyclic molecules with one and two cavities into 2DPs backbones enables the precision synthesis of mechanically interlocked monolayer (MI-M2DP) and bilayer (MI-B2DP). Intriguingly, we have observed an exceptionally high effective Young's modulus of 222.4±51.0 GPa for MI-B2DP, surpassing those of MI-M2DP (130.1±15.2 GPa), vdW-stacked MI-M2DPs (2×MI-M2DP, 8.1±0.9 GPa) and other reported multilayer 2DPs. Modeling studies demonstrate the extraordinary effectiveness of mechanically interlocked structures in minimizing interlayer sliding (~0.1 Å) and energy penalty (320 kcal/mol) in MI-B2DP compared to 2×MI-M2DP (~1.2 Å, 550 kcal/mol), thereby suppressing mechanical relaxation and resulting in prominent structural reinforcement. © 2024, CC BY-NC-ND.

关键词： Monolayers

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Observation of Active Galactic Nuclei with the Large-Sized Telescope prototype of the Cherenkov Telescope Array 38

Observation of Active Galactic Nuclei with the Large-Sized T...

引用

38th International Cosmic Ray Conference, ICRC 2023

作者： Takeishi, R. Álvarez Crespo, N. Arbet-Engels, A. Baquero Larriva, A. Baxter, J. Biederbeck, N. Caroff, S. Di Marco, G. Fallah Ramazani, V. Green, D. Heckmann, L. Láinez, M. Nickel, L. Nievas Rosillo, M. Pons, E. Priyadarshi, C. Sanchez, D.A. Vázquez Acosta, M. Abe, K. Abe, S. Aguasca-Cabot, A. Agudo, I. Antonelli, L.A. Aramo, C. Arcaro, C. Artero, M. Asano, K. Aubert, P. Baktash, A. Bamba, A. Baquero Larriva, A. Baroncelli, L. Barres de Almeida, U. Barrio, J.A. Batkovic, I. Becerra González, J. Bernardini, E. Bernardos, M.I. Bernete Medrano, J. Berti, A. Bhattacharjee, P. Bigongiari, C. Bissaldi, E. Blanch, O. Bonnoli, G. Bordas, P. Bulgarelli, A. Burelli, I. Burmistrov, L. Buscemi, M. Cardillo, M. Carosi, A. Carrasco, M.S. Cassol, F. Cauz, D. Cerasole, D. Ceribella, G. Chai, Y. Cheng, K. Chiavassa, A. Chikawa, M. Chytka, L. Cifuentes, A. Contreras, J.L. Cortina, J. Costantini, H. Dalchenko, M. Dazzi, F. De Angelis, A. de Bony de Lavergne, M. De Lotto, B. De Lucia, M. de Menezes, R. Del Peral, L. Deleglise, G. Delgado, C. Delgado Mengual, J. della Volpe, D. Dellaiera, M. Di Piano, A. Di Pierro, F. Di Pilato, A. Di Tria, R. Di Venere, L. Díaz, C. Dominik, R.M. Dominis Prester, D. Donini, A. Dorner, D. Doro, M. Eisenberger, L. Elsässer, D. Emery, G. Escudero, J. Ferrara, G. Ferrarotto, F. Fiasson, A. Foffano, L. Freixas Coromina, L. Fröse, S. Fukami, S. Fukazawa, Y. Garcia, E. Garcia López, R. Gasbarra, C. Gasparrini, D. Geyer, D. Giesbrecht Paiva, J. Giglietto, N. Giordano, F. Gliwny, P. Godinovic, N. Grau, R. Gunji, S. Günther, P. Hackfeld, J. Hadasch, D. Hahn, A. Hashiyama, K. Hassan, T. Hayashi, K. Heller, M. HerreraLlorente, J. Hirotani, K. Hoffmann, D. Horns, D. Houles, J. Hrabovsky, M. Hrupec, D. Hui, D. Hütten, M. Iarlori, M. Imazawa, R. Inada, T. Inome, Y. Ioka, K. Iori, M. Ishio, K. Jimenez Martinez, I. Jurysek, J. Kagaya, M. Karas, V. Katagiri, H. Kataoka, J. Kerszberg, D. Kobayashi, Y. Kohri, K. Kong, A. Kubo, H. Kushida, J. Lamanna, G. Lamastra, A. Institute for Cosmic Ray Research University of Tokyo Chiba Kashiwa277-8582 Japan Grupo de Electronica Universidad Complutense de Madrid Av. Complutense s/n Madrid28040 Spain Max-Planck-Institut für Physik Föhringer Ring 6 München80805 Germany IPARCOS-UCM Instituto de Física de Partículas y del Cosmos EMFTEL Department Universidad Complutense de Madrid MadridE-28040 Spain Faculty of Science and Technology Universidad del Azuay Cuenca Ecuador Department of Physics TU Dortmund University Otto-Hahn-Str. 4 Dortmund44227 Germany Univ. Savoie Mont Blanc CNRS Laboratoire d’Annecy de Physique des Particules - IN2P3 Annecy74000 France Instituto de Astrofísica de Canarias Departamento de Astrofísica Universidad de La Laguna Tenerife La Laguna Spain Institut für Theoretische Physik Lehrstuhl IV: Plasma-Astroteilchenphysik Ruhr-Universität Bochum Universitätsstraße 150 Bochum44801 Germany The Barcelona Institute of Science and Technology Campus UAB Bellaterra Barcelona08193 Spain Department of Physics Tokai University Japan Departament de Física Quàntica i Astrofísica Institut de Ciències delCosmos Universitat de Barcelona IEEC-UB Spain Instituto de Astrofísica de Andalucía-CSIC Spain EMFTEL department IPARCOS Universidad Complutense de Madrid Spain INAF - Osservatorio Astronomico di Roma Italy INFN Sezione di Napoli Italy INFN Sezione di Padova Università degli Studi di Padova Italy Universität Hamburg Institut für Experimentalphysik Germany Graduate School of Science University of Tokyo Japan Universidad del Azuay Ecuador INAF - Osservatorio di Astrofisica e Scienza dello spazio di Bologna Italy Centro Brasileiro de Pesquisas Físicas Brazil CIEMAT Spain INFN Sezione di Bari Politecnico di Bari Italy INAF - Osservatorio Astronomico di Brera Italy INFN Sezione di Trieste Università degli Studi di Udine Italy University of Geneva Département de physique nucléaire et corpusculaire Switzerland INFN Sezione di Catania Italy Italy Aix Marseille Uni

Cherenkov Telescope Array (CTA) will be the next generation gamma-ray observatory. It will consist of three different sizes of telescopes, with a collective improvement of about an order of magnitude in sensitivity, compared with the current generation gamma-ray telescopes. LargeSized Telescopes (LSTs) will be the most sensitive at energies from tens of GeV up to a few TeVs, and will be the best suited to observe gamma-ray sources such as Active Galactic Nuclei (AGN). The first Large-Sized Telescope prototype (LST-1), inaugurated in 2018 and currently in commissioning phase, has accumulated more than one thousand hours of data to date. From 2020 to 2022, we have detected various gamma-ray sources, and prominent among them are several well-known AGN, like Mrk 421, Mrk 501, 1ES 1959+650, 1ES 0647+250, PG 1553+113, etc. We report on light curves and energy spectra reconstructed out of these observations down to energies of tens of GeV, which is very close to the energy threshold of LST-1. © Copyright owned by the author(s) under the terms of the Creative Commons.

关键词： Active Galactic Nuclei

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Double Perovskite Type (Nh4)3fexco1-Xf6 Electrocatalyst Synthesized Via Low-Temperature Reaction for Efficient Water Oxidation

SSRN

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SSRN 2022年

作者： Li, Yafei Zhai, Xingwu Li, Ju Liu, Yinglun Wang, Gang Yang, Xiaodong Ge, Guixian Key Laboratory of Ecophysics Department of Physics College of Science Shihezi University Shihezi832003 China Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan School of Chemistry and Chemical Engineering Shihezi University Shihezi832003 China Hefei National Laboratory for Physical Sciences at the Microscale School of Chemistry and Materials Science University of Science and Technology of China Hefei230026 China Institute of Electrostatics and Special Power School of Electrical Engineering Dalian University of Technology Dalian116024 China

Developing efficient nonprecious electrocatalysts to accelerate the sluggish oxygen evolution reaction (OER) is of great significance for boosting water splitting. Here, we propose that NH4F can serve as a structure-directing agent to replace the imidazole ligand in ZIF-67 so that Fe cations can be incorporated to form a double perovskite structured bimetallic fluoride [(NH4)3FexCo1-xF6, NFCF]. This NFCF electrocatalyst has an open framework structure with porous hollow, which guarantees lower charge transfer resistance, abundant active sites, and larger electrochemical surface area. DFT calculation verifies that the coexistence of Co and Fe can moderate the OH* adsorption and decrease the energy barrier from O* to OOH* of NFCF during OER catalysis. It requires low overpotentials of 243 and 360 mV to achieve current densities of 10 and 100 mA cm-2 in 1 M KOH, respectively. Moreover, it can work at a constant current of 100 mA cm-2 for up to 100 h. © 2022, The Authors. All rights reserved.

关键词： Density functional theory

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