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Boron Nitride Quantum Dots/Ti_(3)C_(2)T_(x)-MXene Heterostructure For Efficient Electrocatalytic Nitrogen Fixation

Energy & Environmental materials 2022年第4期5卷 1303-1309页

作者： Ke Chu Xingchuan Li Ye Tian Qingqing Li Yali Guo School of Materials Science and Engineering Lanzhou Jiaotong UniversityLanzhou 730070China Department of Physics College of ScienceHebei North UniversityZhangjiakou 075000China

Electrocatalytic N_(2) fixation through N_(2) reduction reaction(NRR)has been regarded as a promising route for sustainable NH_(3) synthesis,while exploring high-performing NRR catalysts is pivotal yet ***,BN quantum dots/Ti_(3)C_(2)T_(x)-MXene(BNQDs/Ti_(3)C_(2)T_(x))heterostructure is demonstrated as an efficient and durable NRR catalyst,exhibiting a high NH_(3) yield of 52.8±3.3μg h^(-1) mg^(-1) with an FE of 19.1±1.6%at0.4 V(***),which stand at the high level among all reported BN-and MXene-based NRR *** computations reveal that the electronic interactions between BNQDs and Ti_(3)C_(2)T_(x) enrich the electron density of B atoms at the heterointerface and endow them with enhanced electron-donating capability for N_(2) activation and ***,the decorated BNQDs can block the active sites of Ti_(3)C_(2)T_(x) for hydrogen evolution,rendering a high N_(2)-to-NH_(3) selectivity.

关键词： Boron nitride quantum dots Density functional theory Electrocatalytic nitrogen fixation MXene

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Two-dimensional Janus perovskite oxynitrides as active photocatalysts for overall water splitting with ferroelectric modulation

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Journal of materials Chemistry A 2023年第35期11卷 19074-19082页

作者： Yu, Zhichao Li, Bowen Bai, Haoyun Pan, Hui Institute of Applied Physics and Materials Engineering University of Macau Macao SAR999708 China Department of Physics and Chemistry Faculty of Science and Technology University of Macau Macao SAR999078 China

Two-dimensional (2D) Janus structure is promising for photocatalytic water splitting because its intrinsic built-in electric field can overpass the bandgap requirements of photocatalysts. However, how to achieve overall water splitting spontaneously in one structure is still difficult. Here, we present a novel family of 2D Janus perovskite oxynitrides, BaXNO2 (X = Ta, Nb, V), with a large intrinsic built-in electric field based on first-principles calculations. Both 2D BaTaNO2 and BaNbNO2 exhibit remarkable activity for photocatalytic overall water splitting. For BaNbNO2, a lowest overpotential of 0.44 V for the oxygen evolution reaction (OER) is realized. The Gibbs free energy of hydrogen adsorption (ΔGH) is near zero (0.02 eV) for BaTaNO2 in the hydrogen evolution reaction (HER). Interestingly, 2D BaVNO2 shows in-plane ferroelectricity due to the displacement of V ions accompanied by a ferroelastic distortion of the lattice, which modulates the band structures, resulting in optimized band alignment. The photocatalytic performance can be further improved by constructing a BaNbNO2/BaVNO2 heterostructure, which has an overpotential of 0.47 V for the OER and ΔGH of 0.16 eV for the HER. Our theoretical investigation provides not only a guidance to design Janus photocatalysts for full water splitting, but also strategies to modulate the photocatalytic performance through ferroelectricity. © 2023 The Royal Society of Chemistry.

关键词： Barium compounds

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Bending the Rule: Naphthobisthiadiazole-Based Terpolymers with Both High Solubility and Crystallinity for Organic Photovoltaics

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ACS Applied Polymer materials 2024年第5期6卷 2586-2593页

作者： Chou, Li-Hui Chen, Fengkun Nakano, Kyohei Yamanaka, Kodai Mikie, Tsubasa Saito, Masahiko Liu, Cheng-Liang Tajima, Keisuke Osaka, Itaru Department of Applied Chemistry Graduate School of Engineering Hiroshima University Hiroshima Higashi-Hiroshima739-8527 Japan Department of Chemical and Materials Engineering National Central University Taoyuan32001 Taiwan Saitama Wako351-0198 Japan Applied Chemistry Program Graduate School of Advanced Science and Engineering Hiroshima University Hiroshima Higashi-Hiroshima739-8527 Japan Department of Materials Science and Engineering National Taiwan University Taipei10617 Taiwan

Achieving a good balance between the crystallinity and solubility is of great importance in the design of π-conjugated polymers. Here, we synthesized a series of terpolymers in which small fractions of a planar V-shaped fused ring, triphenyleno[1,2-c:7,8-c′]bis([1,2,5]thiadiazole) (TPTz), are incorporated into the linear-shaped backbone of a highly crystalline polymer based on naphtho[1,2-c:5,6-c′]bis([1,2,5]thiadiazole) (NTz), PNTz4T. Due to the "bending" structure induced by the TPTz unit, the terpolymers had greatly improved solubility by about 5-9 times compared to the linear-shaped PNTz4T. In particular, the terpolymers preserved the crystallinity of PNTz4T to a considerable extent with a higher fraction of face-on oriented domains in films. As a result, the highly solution-processable terpolymers exhibited high photovoltaic performances and slightly outperformed PNTz4T. Our results indicate that the incorporation of a V-shaped unit into a linearly shaped polymer is a good strategy to develop π-conjugated polymers with high solubility and crystallinity. © 2024 American Chemical Society.

关键词： Solubility

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Negative enthalpy alloys and local chemical ordering:a concept and route leading to synergy of strength and ductility

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National science Review 2024年第4期11卷 172-184页

作者： Zibing An Tao Yang Caijuan Shi Shengcheng Mao Lihua Wang Ang Li Wei Li Xianmeng Xue Ming Sun Yifan Bai Yapeng He Fuzeng Ren Zhouguang Lu Ming Yan Yang Ren Chain-Tsuan Liu Ze Zhang Xiaodong Han Beijing Key Lab of Microstructure and Property of Advanced Materials College of Materials Science &Engineering Beijing University of Technology Department of Materials Science and Engineering City University of Hong Kong Key Laboratory of Partial Acceleration Physics& Technology Institute of High Energy PhysicsChinese Academy of Sciences Department of Materials Science &Engineering Southern University of Science and Technology Department of Physics City University of Hong Kong State Key Laboratory of Silicon Materials Department of Materials Science and Engineering Zhejiang University

Solid solutions are ubiquitous in metals and alloys. Local chemical ordering(LCO) is a fundamental sub-nano/nanoscale process that occurs in many solid solutions and can be used as a microstructure to optimize strength and ductility. However, the formation of LCO has not been fully elucidated, let alone how to provide efficient routes for designing LCO to achieve synergistic effects on both superb strength and ductility. Herein, we propose the formation and control of LCO in negative enthalpy alloys. With engineering negative enthalpy in solid solutions, genetic LCO components are formed in negative enthalpy refractory high-entropy alloys(RHEAs). In contrast to conventional ‘trial-and-error' approaches, the control of LCO by using engineering negative enthalpy in RHEAs is instructive and results in superior strength(1160 MPa) and uniform ductility(24.5%) under tension at ambient temperature, which are among the best reported so far. LCO can promote dislocation cross-slip, enhancing the interaction between dislocations and their accumulation at large tensile strains; sustainable strain hardening can thereby be attained to ensure high ductility of the alloy. This work paves the way for new research fields on negative enthalpy solid solutions and alloys for the synergy of strength and ductility as well as new functions.

关键词： negative enthalpy alloys local chemical ordering strength ductility dislocation

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Robust twin-field quantum key distribution through sending or not sending

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National science Review 2023年第4期10卷 76-85页

作者： Cong Jiang Zong-Wen Yu Xiao-Long Hu Xiang-Bin Wang Jinan Institute of Quantum Technology State Key Laboratory of Low Dimensional Quantum Physics Department of Physics Tsinghua University Data Communication Science and Technology Research Institute School of Physics State Key Laboratory of Optoelectronic Materials and Technologies Sun Yat-sen University Shanghai Branch CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics University of Science and Technology of China Shenzhen Institute for Quantum Science and Engineering and Physics Department Southern University of Science and Technology Frontier Science Center for Quantum Information

The sending-or-not-sending(SNS) protocol is one of the most major variants of the twin-field(TF)quantum key distribution(QKD) protocol and has been realized in a 511-km field fiber, the farthest field experiment to date. In practice, however, all decoy-state methods have unavoidable source errors, and the source errors may be non-random, which compromises the security condition of the existing TF-QKD protocols. In this study, we present a general approach for efficiently calculating the SNS protocol's secure key rate with source errors, by establishing the equivalent protocols through virtual atenuation and the tagged model. This makes the first result for TF QKD in practice where source intensity cannot be controlled exactly. Our method can be combined with the two-way classical communication method such as active odd-parity pairing to further improve the key rate. The numerical results show that if the intensity error is within a few percent, the key rate and secure distance only decrease marginally. The key rate of the recent SNS experiment in the 511-km field fiber is still positive using our method presented here, even if there is a ±9.5% intensity fluctuation. This shows that the SNS protocol is robust against source errors.

关键词： quantum information quantum key distribution sending or not sending twin field source error

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Magnetoelastic coupling driven magnon gap in a honeycomb antiferromagnet

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Physical Review B 2024年第10期110卷 104419页

作者： Jeongheon Choe Andrey Baydin Gaihua Ye Bowen Ma Cynthia Nnokwe Martin Rodriguez-Vega David Lujan Swati Chaudhary Fuyang Tay Jiaming He Hiroyuki Nojiri Jianshi Zhou Gregory A. Fiete Junichiro Kono Rui He Xiaoqin Li Department of Physics Center of Complex Quantum Systems Center for Dynamics and Control of Materials Department of Electrical and Computer Engineering Smalley–Curl Institute Department of Physics Applied Physics Graduate Program Smalley–Curl Institute Department of Mechanical Engineering Institute for Materials Research Department of Physics and Astronomy Department of Materials Science and NanoEngineering

Cobalt titanate, CoTiO3, is a honeycomb antiferromagnet recently confirmed experimentally to host Dirac magnons, topological spin-orbit excitons, and chiral phonons. Here, we investigate a magnon gap at the zone center which calls for a refined spin Hamiltonian. We propose a microscopic model for the magnon gap and attribute it to a lattice-distortion (phonon)-induced higher-order spin interaction. Strong magnetoelastic coupling in CoTiO3 is also evident in Raman spectra, in which the magnetic order exerts a stronger influence on phonons corresponding to in-plane ionic motions than those with out-of-plane motions. We further examine the evolution of the zone-center magnons in a high magnetic field up to 18.5 T via THz absorption spectroscopy measurements. Based on this field dependence, we propose a spin Hamiltonian that not only agrees with magnon dispersion measured by inelastic neutron scattering but also includes fewer exchange constants and a realistic anisotropy term. Our work highlights the broad implications of magnetoelastic coupling in the study of topologically protected bosonic excitations.

关键词： Magnetism Magnons Topological materials Raman spectroscopy Terahertz spectroscopy

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Structure inversion asymmetry enhanced electronic structure and electrical transport in 2D A3SnO(A=Ca,Sr,and Ba)antiperovskite monolayers

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Nano Research 2023年第1期16卷 1779-1791页

作者： Syed Muhammad Alay-e-Abbas Ghulam Abbas Waqas Zulfiqar Muhammad Sajjad Nirpendra Singh J.Andreas Larsson Applied Physics Division of Materials ScienceDepartment of Engineering Sciences and MathematicsLuleåUniversity of Technology97187 LuleåSweden Computational Materials Modeling Laboratory Department of PhysicsGovernment College UniversityFaisalabad 38040Pakistan Department of Energy Conversion and Storage Technical University of Denmark2800 Kgs.LyngbyDenmark Department of Physics Khalifa University of Science and TechnologyAbu Dhabi-127788United Arab Emirates Center for Catalysis and Separation(CeCaS) Khalifa University of Science and TechnologyAbu Dhabi-127788United Arab Emirates

Anti-perovskites A3SnO(A=Ca,Sr,and Ba)are an important class of materials due to the emergence of Dirac cones and tiny mass gaps in their band structures originating from an intricate interplay of crystal symmetry,spin–orbit coupling,and band *** provides an exciting playground for modulating their electronic properties in the two-dimensional(2D)***,we employ first-principles density functional theory(DFT)calculations by combining dispersion-corrected SCAN+rVV10 and mBJ functionals for a comprehensive side-by-side comparison of the structural,thermodynamic,dynamical,mechanical,electronic,and thermoelectric properties of bulk and monolayer(one unit cell thick)A3SnO *** results show that 2D monolayers derived from bulk A3SnO anti-perovskites are structurally and energetically ***,Rashba-type splitting in the electronic structure of Ca3SnO and Sr3SnO monolayers is observed owing to strong spin–orbit coupling and inversion *** the other hand,monolayer Ba3SnO exhibits Dirac cone at the high-symmetryΓpoint due to the domination of band *** on the predicted electronic transport properties,it is shown that inversion asymmetry plays an essential character such that the monolayers Ca3SnO and Sr3SnO outperform thermoelectric performance of their bulk counterparts.

关键词： electrical transport anti-perovskites low-dimensional materials electronic structure mechanical properties

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Thickness-dependent insulator-to-metal transition in epitaxial RuO2 films

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Physical Review materials 2024年第7期8卷 075002-075002页

作者： Anil Kumar Rajapitamahuni Sreejith Nair Zhifei Yang Anusha Kamath Manjeshwar Seung Gyo Jeong William Nunn Bharat Jalan Department of Chemical Engineering and Materials Science School of Physics and Astronomy

Epitaxially grown RuO2 films on TiO2 (110) exhibit significant in-plane strain anisotropy, with a compressive strain of −4.7% along the [001] crystalline direction and a tensile strain of +2.3% along [11¯0]. As the film thickness increases, anisotropic strain relaxation is expected. By fabricating Hall bar devices with current channels along two in-plane directions, 〈001〉 and 〈11¯0〉, we reveal anisotropic in-plane transport in RuO2/TiO2 (110) films grown via the solid-source metal-organic molecular beam epitaxy approach. For film thicknesses (tfilm)≤3.6 nm, the resistivity along 〈001〉 exceeds that along the 〈11¯0〉 direction at all temperatures. With further decrease in film thickness, we uncover a transition from metallic to insulating behavior at tfilm≤2.1 nm. Our combined temperature- and magnetic field-dependent electrical transport measurements reveal that this transition from metallic to insulating behavior is driven by electron-electron interactions.

关键词： Electrical conductivity Electrical properties Hall effect Hopping transport Localization

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Imaging Quantum Interference in a Monolayer Kitaev Quantum Spin Liquid Candidate

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Physical Review X 2024年第4期14卷 041026页

作者： Y. Kohsaka S. Akutagawa S. Omachi Y. Iwamichi T. Ono I. Tanaka S. Tateishi H. Murayama S. Suetsugu K. Hashimoto T. Shibauchi M. O. Takahashi S. Nikolaev T. Mizushima S. Fujimoto T. Terashima T. Asaba Y. Kasahara Y. Matsuda Department of Physics Department of Advanced Materials Science Wako Saitama 351-0198 Japan Department of Materials Engineering Science

Single atomic defects are prominent windows to look into host quantum states because collective responses from the host states emerge as localized states around the defects. Friedel oscillations and Kondo clouds in Fermi liquids are quintessential examples. However, the situation is quite different for quantum spin liquid (QSL), an exotic state of matter with fractionalized quasiparticles and topological order arising from a profound impact of quantum entanglement. Elucidating the underlying local electronic property has been challenging due to the charge neutrality of fractionalized quasiparticles and the insulating nature of QSLs. Here, using spectroscopic-imaging scanning tunneling microscopy, we report atomically resolved images of monolayer α−RuCl3, the most promising Kitaev QSL candidate, on metallic substrates. We find quantum interference in the insulator manifesting as incommensurate and decaying spatial oscillations of the local density of states around defects with a characteristic bias dependence. The oscillation differs from any known spatial structures in its nature and does not exist in other Mott insulators, implying it is an exotic oscillation involved with excitations unique to α−RuCl3. Numerical simulations suggest that the observed oscillation can be reproduced by assuming that itinerant Majorana fermions of Kitaev QSL are scattered across the Majorana Fermi surface. The oscillation provides a new approach to exploring Kitaev QSLs through the local response against defects like Friedel oscillations in metals.

关键词： Local density of states Majorana fermions Quantum spin liquid Honeycomb lattice Monolayer films Film deposition Kitaev model Liquid helium cooling Scanning tunneling microscopy Scanning tunneling spectroscopy

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Achieving broadband near-infrared luminescence in Cr^(3+)-Activated Y_(2)Mg_(2)Al_(2)Si_(2)O_(12)phosphors via multi-site occupancy

Advanced Powder Materials

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Advanced Powder materials 2024年第3期3卷 68-76页

作者： Gui-Hua Li Han-Qi Wei Qi-Hua Yang Zhi-Wei Luo Ge-Mei Cai Li Ma Xiao-Jun Wang School of Materials Science and Engineering Central South UniversityChangsha 410083China Science Center for Phase Diagram&Materials Design and Manufacture Central South UniversityChangsha 410083China Department of Physics Georgia Southern UniversityStatesboroGA 30460United States

Cr^(3+)-activated near-infrared(NIR)phosphors are key for NIR phosphor-converted light emitting diodes(NIR pc-LED).While,the site occupancy of Cr^(3+)is one of the debates that have plagued ***,Y2Mg2Al2-Si_(2)O1_(2)(YMAS)with multiple cationic sites is chosen as host of Cr^(3+)to synthesize YMAS:xCr^(3+)*** YMAS,Cr^(3+)ions occupy simultaneously Al/SiO4 tetrahedral,Mg/AlO6 octahedral,and Y/MgO8 dodecahedral sites which form three luminescent centers named as Cr1,Cr2,and Cr3,***1 and Cr2 relate to an intermediate crystal field,with transitions of^(2)E→^(4)A_(2)and^(4)T_(2)→^(4)A_(2)occurring *** Cr^(3+)concentration increases,the^(4)T_(2)→^(4)A_(2)transition becomes more pronounced in Cr1 and Cr2,resulting in a red-shift and broadband ***3 consistently behaves a weak crystal field and exhibits the broad and long-wavelength ***-range NIR emission centering at 745 nm is realized in YMAS:0.03Cr^(3+)*** phosphor has high internal quantum efficiency(IQE?86%)and satisfying luminescence thermal stability(I423 K?70.2%).Using this phosphor,NIR pc-LEDs with 56.6 mW@320 mA optical output power is packaged and *** study not only demonstrates the Cr^(3+)multi-site occupancy in a certain oxide but also provides a reliable approach via choosing a host with diverse cationic sites and local environments for Cr^(3+)to achieve broadband NIR phosphors.

关键词： Near-infrared phosphor pc-LEDs Cr^(3+) Broadband emission Site occupancy Crystal field

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