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Huang J, Ke C, Qian Z, Liu S. Competing Charge Transfer and Screening Effects in Two-Dimensional Ferroelectric Capacitors. NANO LETTERS 2024; 24:6683-6688. [PMID: 38767925 DOI: 10.1021/acs.nanolett.4c01362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Two-dimensional (2D) ferroelectrics promise ultrathin flexible nanoelectronics, typically utilizing a metal-ferroelectric-metal sandwich structure. Electrodes can either contribute free carriers to screen the depolarization field, enhancing nanoscale ferroelectricity, or induce charge doping, disrupting the long-range crystalline order. We explore electrodes' dual roles in 2D ferroelectric capacitors, supported by first-principles calculations covering a range of electrode work functions. Our results reveal volcano-type relationships between ferroelectric-electrode binding affinity and work function, which are further unified by a quadratic scaling between the binding energy and the transferred interfacial charge. At the monolayer limit, charge transfer dictates the ferroelectric stability and switching properties. This general characteristic is confirmed in various 2D ferroelectrics including α-In2Se3, CuInP2S6, and SnTe. As the ferroelectric layer's thickness increases, the capacitor stability evolves from a charge-transfer-dominated state to a screening-dominated state. The delicate interplay between these two effects has important implications for 2D ferroelectric capacitor applications.
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Affiliation(s)
- Jiawei Huang
- Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University, Hangzhou, Zhejiang 310030, China
| | - Changming Ke
- Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University, Hangzhou, Zhejiang 310030, China
| | - Zhuang Qian
- Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University, Hangzhou, Zhejiang 310030, China
| | - Shi Liu
- Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University, Hangzhou, Zhejiang 310030, China
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Yin Y, Gong Q, Yi M, Guo W. Monolayer polar metals with large piezoelectricity derived from MoSi 2N 4. MATERIALS HORIZONS 2023; 10:5177-5184. [PMID: 37718912 DOI: 10.1039/d3mh00743j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
The advancement of two-dimensional polar metals tends to be limited by the incompatibility between electric polarity and metallicity as well as dimension reduction. Here, we report polar and metallic Janus monolayers of the MoSi2N4 family by breaking the out-of-plane structural symmetry through Z (P/As) substitution of N. Despite the semiconducting nature of MoSi2X4 (X = N/P/As), four Janus MoSi2NxZ4-x monolayers are found to be polar metals owing to the weak coupling between the conducting electrons and electric polarity. The metallicity is originated from the Z substitution induced delocalization of occupied electrons in Mo-d orbitals. The out-of-plane electric polarizations around 1.5-15.7 pC m-1 are determined by the asymmetric out-of-plane charge distribution due to the non-centrosymmetric Janus structure. The corresponding out-of-plane piezoelectricity is further revealed as high as 18.7-73.3 pC m-1 and 0.05-0.25 pm V-1 for the piezoelectric strain and stress coefficients, respectively. The results demonstrate polar metallicity and high out-of-plane piezoelectricity in Janus MoSi2NxZ4-x monolayers and open new vistas for exploiting unusual coexisting properties in monolayers derived from the MoSi2N4 family.
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Affiliation(s)
- Yan Yin
- State Key Laboratory of Mechanics and Control for Aerospace Structures & Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education & Institute for Frontier Science & College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics (NUAA), Nanjing 210016, China.
| | - Qihua Gong
- State Key Laboratory of Mechanics and Control for Aerospace Structures & Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education & Institute for Frontier Science & College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics (NUAA), Nanjing 210016, China.
- MIIT Key Laboratory of Aerospace Information Materials and Physics & College of Physics, Nanjing University of Aeronautics and Astronautics (NUAA), Nanjing 211106, China
| | - Min Yi
- State Key Laboratory of Mechanics and Control for Aerospace Structures & Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education & Institute for Frontier Science & College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics (NUAA), Nanjing 210016, China.
| | - Wanlin Guo
- State Key Laboratory of Mechanics and Control for Aerospace Structures & Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education & Institute for Frontier Science & College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics (NUAA), Nanjing 210016, China.
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Huang J, Ke C, Zhu W, Liu S. One dimensional ferroelectric nanothreads with axial and radial polarization. NANOSCALE HORIZONS 2023; 8:1205-1216. [PMID: 37381975 DOI: 10.1039/d3nh00154g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/30/2023]
Abstract
Long-range ferroelectric crystalline order usually fades away as the spatial dimension decreases, and hence there are few two-dimensional (2D) ferroelectrics and far fewer one-dimensional (1D) ferroelectrics. Due to the depolarization field, low-dimensional ferroelectrics rarely possess the polarization along the direction of reduced dimensionality. Here, using first-principles density functional theory, we explore the structural evolution of nanoribbons of varying widths constructed by cutting a 2D sheet of ferroelectric α-III2VI3 (III = Al, Ga, In; VI = S, Se, Te). We discover a one-dimensional ferroelectric nanothread (1DFENT) of ultrasmall diameter with both axial and radial polarization, potentially enabling ultra-dense data storage with a 1D domain of just three unit cells being the functional unit. The polarization in 1DFENT of Ga2Se3 exhibits an unusual piezoelectric response: a stretching stress along the axial direction will increase both the axial and radial polarization, referred to as the auxetic piezoelectric effect. Utilizing the intrinsically flat electronic bands, we demonstrate the coexistence of ferroelectricity and ferromagnetism in 1DFENT and a counterintuitive charge-doping-induced metal-to-insulator transition. The 1DFENT with both axial and radial polarization offers a counterexample to the Mermin-Wagner theorem in 1D and suggests a new platform for the design of ultrahigh-density memory and the exploration of exotic states of matter.
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Affiliation(s)
- Jiawei Huang
- Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University, Hangzhou, Zhejiang 310030, China.
| | - Changming Ke
- Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University, Hangzhou, Zhejiang 310030, China.
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Wei Zhu
- Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University, Hangzhou, Zhejiang 310030, China.
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Shi Liu
- Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University, Hangzhou, Zhejiang 310030, China.
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
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An C, Wang T, Wang S, Chen X, Han X, Wu S, Deng Q, Zhao L, Hu N. Ultrasonic-assisted preparation of two-dimensional materials for electrocatalysts. ULTRASONICS SONOCHEMISTRY 2023; 98:106503. [PMID: 37393853 PMCID: PMC10316695 DOI: 10.1016/j.ultsonch.2023.106503] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 06/11/2023] [Accepted: 06/21/2023] [Indexed: 07/04/2023]
Abstract
Developing green, environmental, sustainable new energy sources is an important problem to be solved in the world. Among the new energy technologies, water splitting system, fuel cell technology and metal-air battery technology are the main energy production and conversion methods, which involve three main electrocatalytic reactions, hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). The efficiency of the electrocatalytic reaction and the power consumption are very dependent on the activity of the electrocatalysts. Among various electrocatalysts, the two-dimensional (2D) materials have received widespread attention due to multiple advantages, such as their easy availability and low price. What' important is that they have adjustable physical and chemical properties. It is possible to develop them as electrocatalysts to replace the noble metals. Therefore, the design of two-dimensional electrocatalysts is a focus in the research area. Some recent advances in ultrasound-assisted preparation of two-dimensional (2D) materials have been overviewed according to the kind of materials in this review. Firstly, the effect of the ultrasonic cavitation and its applications in the synthesis of inorganic materials are introduced. The ultrasonic-assisted synthesis of representative 2D materials for example transition metal dichalcogenides (TMDs), graphene, layered double metal hydroxide (LDH), and MXene, and their catalytic properties as electrocatalysts are discussed in detail. For example, the CoMoS4 electrocatalysts have been synthesized through a facile ultrasound-assisted hydrothermal method. The obatined HER and OER overpotential of CoMoS4 electrode is 141 and 250 mV, respectively. This review points out some problems that need to be solved urgently at present, and provides some ideas for designing and constructing two-dimensional materials with better electrocatalytic performance.
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Affiliation(s)
- Cuihua An
- Key Laboratory of Hebei Province on Scale-span Intelligent Equipment Technology and School of Mechanical Engineering, Hebei University of Technology, Tianjin 300401, China; Guangdong Provincial Key Laboratory of Electronic Functional Materials and Devices, Huizhou University, Huizhou 516001, Guangdong, China
| | - Tianyu Wang
- Key Laboratory of Hebei Province on Scale-span Intelligent Equipment Technology and School of Mechanical Engineering, Hebei University of Technology, Tianjin 300401, China
| | - Shikang Wang
- Key Laboratory of Hebei Province on Scale-span Intelligent Equipment Technology and School of Mechanical Engineering, Hebei University of Technology, Tianjin 300401, China
| | - Xiaodong Chen
- Guangdong Provincial Key Laboratory of Electronic Functional Materials and Devices, Huizhou University, Huizhou 516001, Guangdong, China
| | - Xiaopeng Han
- School of Materials Science and Engineering, Tianjin University, Tianjin 300350, China
| | - Shuai Wu
- Key Laboratory of Hebei Province on Scale-span Intelligent Equipment Technology and School of Mechanical Engineering, Hebei University of Technology, Tianjin 300401, China.
| | - Qibo Deng
- Key Laboratory of Hebei Province on Scale-span Intelligent Equipment Technology and School of Mechanical Engineering, Hebei University of Technology, Tianjin 300401, China; Advanced Equipment Research Institute Co., Ltd. of HEBUT, Tianjin 300401, China.
| | - Libin Zhao
- Key Laboratory of Hebei Province on Scale-span Intelligent Equipment Technology and School of Mechanical Engineering, Hebei University of Technology, Tianjin 300401, China; Advanced Equipment Research Institute Co., Ltd. of HEBUT, Tianjin 300401, China
| | - Ning Hu
- Key Laboratory of Hebei Province on Scale-span Intelligent Equipment Technology and School of Mechanical Engineering, Hebei University of Technology, Tianjin 300401, China; Advanced Equipment Research Institute Co., Ltd. of HEBUT, Tianjin 300401, China.
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Ke C, Hu Y, Liu S. Depolarization induced III-V triatomic layers with tristable polarization states. NANOSCALE HORIZONS 2023; 8:616-623. [PMID: 36945876 DOI: 10.1039/d3nh00026e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The integration of ferroelectrics that exhibit high dielectric, piezoelectric, and thermal compatibility with the mainstream semiconductor industry will enable novel device types for widespread applications, and yet there are few silicon-compatible ferroelectrics suitable for device downscaling. We demonstrate with first-principles calculations that the enhanced depolarization field at the nanoscale can be utilized to soften unswitchable wurtzite III-V semiconductors, resulting in ultrathin two-dimensional (2D) sheets possessing reversible polarization states. A 2D sheet of AlSb consisting of three atomic planes is identified to host both ferroelectricity and antiferroelectricity, and the tristate switching is accompanied by a metal-semiconductor transition. The thermodynamic stability and potential synthesizability of the triatomic layer are corroborated with phonon spectrum calculations, ab initio molecular dynamics simulations, and variable-composition evolutionary structure search. We propose a 2D AlSb-based homojunction field effect transistor that supports three distinct and nonvolatile resistance states. This new class of III-V semiconductor-derived 2D materials with dual ferroelectricity and antiferroelectricity opens up the opportunity for nonvolatile multibit-based integrated nanoelectronics.
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Affiliation(s)
- Changming Ke
- Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University, Hangzhou, Zhejiang 310030, China.
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Yihao Hu
- Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University, Hangzhou, Zhejiang 310030, China.
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Shi Liu
- Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University, Hangzhou, Zhejiang 310030, China.
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
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