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Effect of Reaction Atmosphere on Catalytic CO Oxidation Over Cu-Based Bimetallic Nanoclusters on a CeO2 Support

Physical Review Applied 2023年第3期20卷 034051-034051页

作者： Long Zhang Jing Pan Min Li Ivo A.W. Filot Emiel J.M. Hensen Hui Wang School of Physics Hunan Key Laboratory of Super Microstructure and Ultrafast Process Hunan Key Laboratory of Nanophotonics and Devices State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 China Department of Chemical Engineering and Chemistry Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven Netherlands

Understanding the nature of active sites and the catalytic properties of oxide-supported bimetallic clusters under reaction conditions remains challenging. In this study, we combine first-principles calculations with genetic algorithm and grand canonical Monte Carlo methods to reveal the structures and compositions of CeO2-supported Cu-based bimetallic clusters in an oxygen-rich environment. Oxidized Cu4X4 (X = Pd, Pt, and Rh) bimetallic clusters on CeO2(111) are stable and exhibit different catalytic properties during CO oxidation compared with the pristine bimetallic clusters. Microkinetic simulations predict that CeO2(111)-supported Cu4Pd4O10, Cu4Pt4O11, and Cu4Rh4O14 clusters have much higher CO oxidation activity than the supported Cu4Pd4, Cu4Pt4, and Cu4Rh4 clusters; this is ascribed to the moderate CO adsorption strength and active oxygen on oxidized alloy clusters. A mechanistic study suggests that CO oxidation occurs via the O2 associative reaction mechanism on the Cu4Pd4O10 and Cu4Pt4O11 clusters, while it proceeds through the O2 dissociative reaction mechanism on the Cu4Rh4O14 cluster. Our calculations further predict that CO oxidation on the Cu4Rh4O14 cluster exhibits a low apparent activation energy, indicating that the oxidized cluster possesses excellent CO oxidation activity. This work demonstrates that the catalytic activity and reaction mechanism vary with the composition and oxidation state of the alloy nanocluster under the reaction conditions and emphasizes the influence of the reaction atmosphere on the reaction mechanisms and catalytic activity of oxide-supported alloy catalysts.

关键词： Chemical binding Chemical reactions Density functional theory Density of states Electrocatalysis Electronic structure Electronic structure of atoms & molecules Molecular dissociation Potential energy surfaces

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Effect of layered-coupling in twisted WSe_(2) moiré superlattices

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Nano Research 2023年第2期16卷 3435-3442页

作者： Biao Wu Haihong Zheng Shaofei Li Chang-Tian Wang Junnan Ding Jun He Zongwen Liu Jian-Tao Wang Yanping Liu School of Physics and Electronics Hunan Key Laboratory for Super-microstructure and Ultrafast ProcessCentral South UniversityChangsha 410083China State Key Laboratory of High-Performance Complex Manufacturing Central South UniversityChangsha 410083China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China School of Chemical and Biomolecular Engineering The University of SydneyNSW 2006Australia The University of Sydney Nano Institute The University of SydneyNSW 2006Australia Songshan Lake Materials Laboratory Dongguan 523808China Shenzhen Research Institute of Central South University Shenzhen 518000China

Recently,the discovery of a variety of moiré-related properties in the twisted vertical stacking of two different monolayers has attracted considerable *** introduction of small twist angles in transition metal dichalcogenide(TMD)heterostructures leads to the emergence of moirépotentials,which provide a fascinating platform for the study of strong interactions of *** there has been extensive research on moiréexcitons in twisted bilayer superlattices,the capture and study of moiréexcitons in homostructure superlattices with layer-coupling effects remain ***,we present the observation of moiréexcitons in the twisted 1L-WSe_(2)/1L-WSe_(2)and 1L-WSe_(2)/2L-WSe_(2)homostructures with various layer-coupling *** results reveal that the moirépotential increases(~260%)as the number of underlying layers decreases,indicating the effect of layer coupling on the modulation of the moiré*** effects of the temperature and laser power dependence as well as valley polarization on moiréexcitons were further demonstrated,and the crucial spectral features observed were *** findings pave the way for exploring quantum phenomena and related applications of quantum information.

关键词： twisted homostructures moirésuperlattices moirépotential layer-coupling

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Designing Surface-Functionalized Ti3C2T2−Cs3Bi2Br9(T=O,Cl,OH, or F) Heterostructures for Perovskite Optoelectronic Applications

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Physical Review Applied 2022年第5期18卷 054036-054036页

作者： Biao Liu Xiangxiang Feng Mengqiu Long Meng-Qiu Cai Junliang Yang Hunan Key Laboratory for Super-microstructure and Ultrafast Process School of Physics and Electronics Central South University Changsha 410083 Hunan China School of Physics and Electronics Science Hunan University Changsha 410082 Hunan China

MXene has emerged as one of the frontier two-dimensional materials. In this work, Ti3C2T2(T=−O,−Cl,−OH, or −F) MXene-Cs3Bi2Br9 perovskite heterostructures are constructed, and the various surface terminations of Ti3C2T2 can achieve functionalized perovskite optoelectronic applications in the heterostructures. Lattice-mismatch rates of the Ti3C2T2 and Cs3Bi2Br9 heterostructures are only about 1%, which makes the electronic properties of Cs3Bi2Br9 independent of lattice stress in the heterostructures. The binding energies of the Ti3C2T2/Cs3Bi2Br9 interfaces are quite low, especially at the Ti3C2(OH)2/Cs3Bi2Br9 interface. Due to the adjustable work function (WF) of Ti3C2T2, the types of interface contacts are different, including n- and p-type Schottky contacts and an ohmic contact. The Ti3C2(OH)2/Cs3Bi2Br9 interface is an ohmic contact; this is attributed to the big difference in the WFs of Ti3C2(OH)2 and Cs3Bi2Br9, which could greatly boost the charge-carrier separation and transfer efficiency. In addition, the constructed heterostructures enhance the optical absorption coefficient and reduce charge-carrier effective masses. These results indicate that the Ti3C2T2/Cs3Bi2Br9 heterostructures, especially Ti3C2(OH)2/Cs3Bi2Br9, can significantly improve the optoelectronic performance of the lead-free perovskite.

关键词： Electronic structure Optoelectronics 2-dimensional systems Heterostructures MAX phase compounds Organic-inorganic hybrid perovskites Photovoltaic absorbers Density functional calculations

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Revisiting the heterostructure and electric-field-modulation characteristics of the Ruddlesden-Popper perovskite Cs2Pb(SCN)2Br2 with low exciton-binding energy

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Physical Review Applied 2024年第6期22卷 064066-064066页

作者： Yan-Long Chen Jun Luo Biao Liu Jun-Liang Yang Hai-Lin Yu Meng-Qiu Cai Hunan Provincial Key Laboratory of High-Energy Scale Physics and Applications School of Physics and Electronics Hunan University Changsha 410082 People’s Republic of China Hunan Key Laboratory for Super-microstructure and Ultrafast Process School of Physics and Electronics Central South University Changsha 410083 Hunan People’s Republic of China School of Electronic and Information Engineering Changshu Institute of Technology Changshu 215500 People’s Republic of China

Two-dimensional Ruddlesden-Popper perovskites have garnered significant attention due to their excellent environmental stability, tunable photophysical properties, and other advantageous characteristics. Although two-dimensional perovskites have been extensively studied in the field of photoluminescence, their application in photovoltaics has been limited due to high exciton-binding energy. Recently, another Ruddlesden-Popper perovskite Cs2Pb(SCN)2Br2 has been synthesized. Compared to most two-dimensional perovskites, Cs2Pb(SCN)2Br2 boasts the advantages of low exciton-binding energy and a narrow optical band gap. To explore the potential of two-dimensional perovskites in photovoltaic applications, an all-inorganic two-dimensional heterojunction Cs2Pb(SCN)2Br2/MoS2 was investigated using first-principles calculations based on density-functional theory (DFT). Our calculation results demonstrate that the heterojunction exhibits significantly enhanced optical absorption properties and carrier mobility compared to Cs2Pb(SCN)2Br2 material. The heterojunction features a typical type-II band alignment, making it highly suitable for photovoltaic applications such as solar cells. We also applied a longitudinal electric field to the heterojunction in calculations, thereby regulating its band alignment. The calculation results reveal that the type-II band alignment of the heterojunction can be transformed into type-I and type-III alignments. These findings significantly expand the application potential of the heterojunction in electronic and optoelectronic devices.

关键词： Heterojunctions

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Introduction of Bimetallic Oxide-Modified Carbon Nanotubes for Boosting the Energy Storage Performance of Nico-Ldh Based In-Plane Micro-supercapacitors on Paper

SSRN

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SSRN 2024年

作者： Zhang, Chi Zhu, Zhixiao Zhang, Yanke Shao, Weixuan Wu, Di Peng, Guannan Liu, Zhengchun Hunan Key Laboratory of Super Microstructure and Ultrafast Process School of Physics and Electronics Central South University Changsha410083 China College of Materials Science and Engineering Hunan Joint International Laboratory of Advanced Materials and Technology for Clean Energy Hunan University Changsha410082 China

In-plane micro-supercapacitors (IMSCs) have greater promise for use in flexible wearable electronics than traditional stacked configurations due to their ease of integration and conformability. Nickel-cobalt layered double hydroxide (NiCo-LDH) has garnered significant interest as a stellar material for supercapacitors because of its affordable price, regular morphology, and high theoretical capacity. Unfortunately, the intrinsic poor conductivity of LDH materials means that long-term stable cycling and the desirable energy density are never achieved by supercapacitors. To ameliorate this disadvantage, the self-templated approach has been successfully applied in this research to prepare carbon nanotubes (CNTs) with heterogeneous architectures and numerous phase interfaces. This CNT with a typical three-dimensional structure is assembled from carbon nanosheets adorned with WO2 and MoO2 nanoparticles. When combined with LDH in a suitable ratio, the composite electrode's conductivity significantly improves, showing increased capacity and cycling stability. In contrast to commercial CNTs, the larger size of the prepared WO2/MoO2@P, N-CNTs serve a superior supporting and connecting role, thereby preventing the NiCo-LDH from aggregating. Under the best conditions, the composite electrode demonstrates a capacity of 1237 C g-1 at 1 A g-1 and an optimal capacity retention of more than 92%. For the IMSC devices, the composite materials as the positive electrode achieve an energy density of 0.0590 mWh cm-2, and no capacity degradation is observed after 10,000 cycles. In addition, bending tests have demonstrated the mechanical stability of the IMSCs. Therefore, this strategy of mixing highly conductive WO2/MoO2@P, N-CNTs can effectively improve the conductivity of the composite material and the mechanical properties of the overall device. And, this idea can be further extended to the preparation and application of other wearable devices as well. © 2024, The Authors. All rights r

关键词： Carbon nanotubes

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Enhanced valley polarization in WSe_(2)/YIG heterostructures via interfacial magnetic exchange effect

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Nano Research 2023年第7期16卷 10580-10586页

作者： Haihong Zheng Biao Wu Chang-Tian Wang Shaofei Li Jun He Zongwen Liu Jian-Tao Wang Guoqiang Yu Ji-An Duan Yanping Liu School of Physics and Electronics Hunan Key Laboratory for Super-microstructure and Ultrafast ProcessCentral South UniversityChangsha 410083China State Key Laboratory of Precision Manufacturing for Extreme Service Performance Central South UniversityChangsha 410083China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China School of Chemical and Biomolecular Engineering The University of SydneyNSW 2006Australia The University of Sydney Nano Institute The University of SydneyNSW 2006Australia Songshan Lake Materials Laboratory Dongguan 523808China Shenzhen Research Institute of Central South University Shenzhen 518057China

Exploiting the valley degrees of freedom as information carriers provides new opportunities for the development of *** transition metal dichalcogenides(TMDs)with broken space-inversion symmetry exhibit emerging valley pseudospins,making them ideal platforms for studying valley ***,intervalley scattering of different energy valleys limits the achievable degree of valley ***,we constructed WSe_(2)/yttrium iron garnet(YIG)heterostructures and demonstrated that the interfacial magnetic exchange effect on the YIG magnetic substrate can enhance valley polarization by up to 63%,significantly higher than that of a monolayer WSe_(2)on SiO_(2)/Si(11%).Additionally,multiple sharp exciton peaks appear in the WSe_(2)/YIG heterostructures due to the strong magnetic proximity effect at the magnetic-substrate interface that enhances exciton emission ***,under the effect of external magnetic field,the magnetic direction of the magnetic substrate enhances valley polarization,further demonstrating that the magnetic proximity effect regulates valley *** results provide a new way to regulate valley polarization and demonstrate the promising application of magnetic heterojunctions in magneto-optoelectronics.

关键词： magnetic exchange effect valley polarization two-dimensional valleytronics magnetic substrate

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Highly anisotropic thermal conductivity of few-layer CrOCl for efficient heat dissipation in graphene device

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Nano Research 2022年第10期15卷 9377-9385页

作者： Xiaoming Zheng Yuehua Wei Zhenhua Wei Wei Luo Xiao Guo Xiangzhe Zhang Jinxin Liu Yangbo Chen Gang Peng Weiwei Cai Shiqiao Qin Han Huang Chuyun Deng Xueao Zhang College of Physical Science and Technology Xiamen UniversityXiamen 361005China College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China College of Arts and Sciences National University of Defense TechnologyChangsha 410073China Hunan Key Laboratory of Super-microstructure and Ultrafast Process School of Physics and ElectronicsCentral South UniversityChangsha 410083China Jiujiang Research Institute of Xiamen University Jiujiang 332105China

With the packing density growing continuously in integrated electronic devices,sufficient heat dissipation becomes a serious ***,dielectric materials with high thermal conductivity have brought insight into effective dissipation of waste heat in electronic devices to prevent them from overheating and guarantee the performance *** CrOCl,an antiferromagnetic insulator with low-symmetry crystal structure and atomic level flatness,might be a promising solution to the thermal ***,we have systematically studied the thermal transport of suspended few-layer CrOCl flakes by microRaman *** CrOCl flakes exhibit high thermal conductivities along zigzag direction,from~392±33 to~1,017±46 W·m^(−1)·K^(−1) with flake thickness from 2 to 50 ***,pronounced thickness-dependent thermal conductivity ratio(/from~2.8±0.24 to~4.3±0.25)has been observed in the CrOCl flakes,attributed to the discrepancy of phonon dispersion and phonon surface *** a demonstration to the heat sink application of layered CrOCl,we then investigate the energy dissipation in graphene devices on CrOCl,SiO_(2) and hexagonal boron nitride(h-BN)substrates,*** graphene device temperature rise on CrOCl is only 15.4%of that on SiO_(2) and 30%on h-BN upon the same electric power density,indicating the efficient heat dissipation of graphene device on *** study provides new insights into two-dimentional(2D)dielectric material with high thermal conductivity and strong anisotropy for the application of thermal management in electronic devices.

关键词： CrOCl High thermal conductivity strong anisotropy efficient heat dissipation heat sink graphene devices

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Structure of Amorphous Two-Dimensional Materials:Elemental Monolayer Amorphous Carbon versus Binary Monolayer Amorphous Boron Nitride

Structure of Amorphous Two-Dimensional Materials:Elemental M...

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中国真空学会2023学术年会、第十六届国际真空科学与工程应用学术会议（VSEA-16）

作者： Xi Zhang Yu-Tian Zhang Yun-Peng Wang Yu-Yang Zhang Shixuan Du University of Chinese Academy of Sciences and Institute of Physics Chinese Academy of Sciences Hunan Key Laboratory for Super Microstructure and Ultrafast Process School of Physics and ElectronicsCentral South University

The structure of amorphous materials has been debated since the 1930s as a binary question: amorphous materials are either Zachariasen continuous random networks（Z-CRNs） or Z-CRNs containing crystallites. It was recently demonstrated,however,that amorphous diamond can be synthesized in either form. Here we address the question of the structure of single-atom-thick amorphous monolayers. We reanalyze the results of prior simulations for amorphous graphene and report kinetic Monte Carlo simulations based on alternative algorithms. We find that crystallite-containing Z-CRN is the favored structure of elemental amorphous graphene,as recently fabricated,whereas the most likely structure of binary monolayer amorphous BN is altogether different than either of the two long-debated options: it is a compositionally disordered "pseudoCRN" comprising a mix of B-N and noncanonical B-B and N-N bonds and containing "pseudocrystallites",namely,honeycomb regions made of noncanonical hexagons. These results suggest that compound amorphous 2D or 3D materials have more options than the binary choice,which has implications for other nonelemental 2D and bulk amorphous materials.

关键词： Amorphous materials 2D materials kinetic Monte Carlo pseudocrystallites

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Contact effects on electron transport along disordered borophene nanoribbons with line defects

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Physical Review B 2024年第16期109卷 165437-165437页

作者： Pei-Jia Hu Zeng-Ren Liang Jia-Wen Sun Tie-Feng Fang Ai-Min Guo Qing-Feng Sun Hunan Key Laboratory for Super-microstructure and Ultrafast Process School of Physics Central South University Changsha 410083 China School of Sciences Nantong University Nantong 226019 China International Center for Quantum Materials School of Physics Peking University Beijing 100871 China Hefei National Laboratory Hefei 230088 China

Line defects (LDs) in borophenes, which occur at the interface between two different boron sheets, have garnered considerable interest. Motivated by recent advancements in the synthesis of diverse borophene polymorphs and heterojunctions, we investigate the contact effects on electron transport through two-terminal disordered borophene nanoribbons (BNRs) with a random distribution of LDs. The source and drain are chosen from the following four semi-infinite electrodes: ν1/5 BNR, ν1/6 BNR, ν1/3 BNR, and square lattice (SL). Despite the substantial reduction in the overall conductance of disordered BNRs, several resonant peaks can appear in the transmission spectra, regardless of inhomogeneous model parameters, nanoribbon length and width, and contact configuration. The amplitude of all the resonant peaks is exactly the conductance quantum G0 when both electrodes are taken as the ν1/5 or ν1/6 BNR. In contrast, the peak amplitude will be less than G0 when either electrode is taken as the ν1/3 BNR or SL. Notably, some resonant peaks completely vanish for the contact configuration of the ν1/3 BNR, a phenomenon termed as the resonant peak filtering effect, which can be understood from the structure-property relationships associated with the local current distribution. Additionally, the distribution of conductance at off-resonant energies can be well fitted by the Anderson localization theory. And the evolution of the resonant peaks with the nanoribbon width is also revealed. These findings contribute to the understanding of structure-property relationships, which is valuable for designing borophene-based nanodevices.

关键词： Transport phenomena Nanoribbon Green's function methods Tight-binding model

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Thermal transport of monolayer amorphous carbon and boron nitride

Thermal transport of monolayer amorphous carbon and boron ni...

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中国真空学会2023学术年会、第十六届国际真空科学与工程应用学术会议（VSEA-16）

作者： Yi-Yang Yin Yu-Tian Zhang Yun-Peng Wang Yu-Yang Zhang Shixuan Du University of Chinese Academy of Sciences and Institute of Physics Chinese Academy of Sciences Hunan Key Laboratory for Super Microstructure and Ultrafast Process School of Physics and ElectronicsCentral South University

Two-dimentional materials show intriguing properties in many aspects,including thermal transport *** and h-BN are two well-known examples among them that possess very high thermal ***,thermal transport properties of their amorphous counter parts remain unclear due to the absence of an accurate *** this work,we report calculations of the in-plane thermal conductivities of monolayer amorphous carbon（MAC） and monolayer amorphous boron nitride（ma-BN）,by reverse nonequilibrium molecular dynamics *** find that the thermal conductivities of both MAC and ma-BN are about two orders of magnitude smaller than their crystalline counter parts,and are independent of temperature and strain due to their extremely short heat carrier mean free ***,the ma-BN shows strong vibrational localization across the frequency range,while the MAC exhibits a unique extended G diffusion mode due to its sp2 hybridization and the broken Eg *** present results reveal the intrinsic low thermal conductivities of MAC and ma-BN,suggesting potential applications of these two materials in thermal management.

关键词： 2D materials amorphous thermal transport carbon boron nitride

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