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Zhou X, Shen B, Zhai J, Yuan J, Hedin N. Enhanced Generation of Reactive Oxygen Species via Piezoelectrics based on p-n Heterojunctions with Built-In Electric Field. ACS APPLIED MATERIALS & INTERFACES 2024. [PMID: 38595048 DOI: 10.1021/acsami.4c01283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
Tuning the charge transfer processes through a built-in electric field is an effective way to accelerate the dynamics of electro- and photocatalytic reactions. However, the coupling of the built-in electric field of p-n heterojunctions and the microstrain-induced polarization on the impact of piezocatalysis has not been fully explored. Herein, we demonstrate the role of the built-in electric field of p-type BiOI/n-type BiVO4 heterojunctions in enhancing their piezocatalytic behaviors. The highly crystalline p-n heterojunction is synthesized by using a coprecipitation method under ambient aqueous conditions. Under ultrasonic irradiation in water exposed to air, the p-n heterojunctions exhibit significantly higher production rates of reactive species (·OH, ·O2-, and 1O2) as compared to isolated BiVO4 and BiOI. Also, the piezocatalytic rate of H2O2 production with the BiOI/BiVO4 heterojunction reaches 480 μmol g-1 h-1, which is 1.6- and 12-fold higher than those of BiVO4 and BiOI, respectively. Furthermore, the p-n heterojunction maintains a highly stable H2O2 production rate under ultrasonic irradiation for up to 5 h. The results from the experiments and equation-driven simulations of the strain and piezoelectric potential distributions indicate that the piezocatalytic reactivity of the p-n heterojunction resulted from the polarization intensity induced by periodic ultrasound, which is enhanced by the built-in electric field of the p-n heterojunctions. This study provides new insights into the design of piezocatalysts and opens up new prospects for applications in medicine, environmental remediation, and sonochemical sensors.
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Affiliation(s)
- Xiaofeng Zhou
- School of Materials Science and Engineering, Tongji University, Shanghai 201804, China
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm SE-106 91, Sweden
| | - Bo Shen
- School of Materials Science and Engineering, Tongji University, Shanghai 201804, China
| | - Jiwei Zhai
- School of Materials Science and Engineering, Tongji University, Shanghai 201804, China
| | - Jiayin Yuan
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm SE-106 91, Sweden
| | - Niklas Hedin
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm SE-106 91, Sweden
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2
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Chen Y, Zhang Y, Wang W, Song X, Jia LG, Zhang C, Zhou L, Han X, Yang HX, Liu LW, Si C, Gao HJ, Wang YL. Visualization of Confined Electrons at Grain Boundaries in a Monolayer Charge-Density-Wave Metal. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023:e2306171. [PMID: 37984874 DOI: 10.1002/advs.202306171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 10/11/2023] [Indexed: 11/22/2023]
Abstract
1D grain boundaries in transition metal dichalcogenides (TMDs) are ideal for investigating the collective electron behavior in confined systems. However, clear identification of atomic structures at the grain boundaries, as well as precise characterization of the electronic ground states, have largely been elusive. Here, direct evidence for the confined electronic states and the charge density modulations at mirror twin boundaries (MTBs) of monolayer NbSe2 , a representative charge-density-wave (CDW) metal, is provided. The scanning tunneling microscopy (STM) measurements, accompanied by the first-principles calculations, reveal that there are two types of MTBs in monolayer NbSe2 , both of which exhibit band bending effect and 1D boundary states. Moreover, the intrinsic CDW signatures of monolayer NbSe2 are dramatically suppressed as approaching an isolated MTB but can be either enhanced or suppressed in the MTB-constituted confined wedges. Such a phenomenon can be well explained by the MTB-CDW interference interactions. The results reveal the underlying physics of the confined electrons at MTBs of CDW metals, paving the way for the grain boundary engineering of the functionality.
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Affiliation(s)
- Yaoyao Chen
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Yu Zhang
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, 100081, P. R. China
- Advanced Research Institute of Multidisciplinary Sciences, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Wei Wang
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, P. R. China
| | - Xuan Song
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Liang-Guang Jia
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Can Zhang
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Lili Zhou
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Xu Han
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Hui-Xia Yang
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Li-Wei Liu
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Chen Si
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, P. R. China
| | - Hong-Jun Gao
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Ye-Liang Wang
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, 100081, P. R. China
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3
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Kim HW. Recent progress in the role of grain boundaries in two-dimensional transition metal dichalcogenides studied using scanning tunneling microscopy/spectroscopy. Appl Microsc 2023; 53:5. [PMID: 37458942 DOI: 10.1186/s42649-023-00088-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 06/20/2023] [Indexed: 07/20/2023] Open
Abstract
Grain boundaries (GBs) are one- or two-dimensional (2D) defects, which are universal in crystals and play a crucial role in determining their mechanical, electrical, optical, and thermoelectric properties. In general, GBs tend to decrease electrical or thermal conductivity, and consequently degrade the performance of devices. However, the unusual characteristics of GBs have led to the production of a new class of memristors with 2D semiconducting transition metal dichalcogenides (TMDs) and the creation of conducting channels in 2D topological insulators. Therefore, understanding the nature of GBs and their influence on device applications emphasizes the importance of GB engineering for future 2D TMD-based devices. This review discusses recent progress made in the investigation of various roles of GBs in 2D TMDs characterized via scanning tunneling microscopy/spectroscopy.
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Affiliation(s)
- Hyo Won Kim
- Samsung Advanced Institute of Technology, Suwon, 13595, Korea.
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4
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Haastrup MJ, Bianchi M, Lammich L, Lauritsen JV. The interface of in-situgrown single-layer epitaxial MoS 2on SrTiO 3(001) and (111). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:194001. [PMID: 36827739 DOI: 10.1088/1361-648x/acbf19] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 02/24/2023] [Indexed: 06/18/2023]
Abstract
SrTiO3(STO) is a versatile substrate with a high dielectric constant, which may be used in heterostructures with 2D materials, such as MoS2, to induce interesting changes to the electronic structure. STO single crystal substrates have previously been shown to support the growth of well-defined epitaxial single-layer (SL) MoS2crystals. The STO substrate is already known to renormalize the electronic bandgap of SL MoS2, but the electronic nature of the interface and its dependence on epitaxy are still unclear. Herein, we have investigated anin-situphysical vapor deposition (PVD) method, which could eliminate the need for ambient transfer between substrate preparation, subsequent MoS2growth and surface characterization. Based on this, we then investigate the structure and epitaxial alignment of pristine SL MoS2in various surface coverages grown on two STO substrates with a different initial surface lattice, the STO(001)(4 × 2) and STO(111)-(9/5 × 9/5) reconstructed surfaces, respectively. Scanning tunneling microscopy shows that epitaxial alignment of the SL MoS2is present for both systems, reflected by orientation of MoS2edges and a distinct moiré pattern visible on the MoS2(0001) basal place. Upon increasing the SL MoS2coverage, the presence of four distinct rotational domains on the STO(001) substrate, whilst only two on STO(111), is seen to control the possibilities for the formation of coherent MoS2domains with the same orientation. The presented methodology relies on standard PVD in ultra-high vacuum and it may be extended to other systems to help explore pristine two-dimensional transition metal dichalcogenide/STO systems in general.
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Affiliation(s)
- Mark J Haastrup
- Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - Marco Bianchi
- Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - Lutz Lammich
- Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - Jeppe V Lauritsen
- Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
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5
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Yang SJ, Choi MY, Kim CJ. Engineering Grain Boundaries in Two-Dimensional Electronic Materials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2203425. [PMID: 35777352 DOI: 10.1002/adma.202203425] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 06/30/2022] [Indexed: 06/15/2023]
Abstract
Engineering the boundary structures in 2D materials provides an unprecedented opportunity to program the physical properties of the materials with extensive tunability and realize innovative devices with advanced functionalities. However, structural engineering technology is still in its infancy, and creating artificial boundary structures with high reproducibility remains difficult. In this review, various emergent properties of 2D materials with different grain boundaries, and the current techniques to control the structures, are introduced. The remaining challenges for scalable and reproducible structure control and the outlook on the future directions of the related techniques are also discussed.
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Affiliation(s)
- Seong-Jun Yang
- Center for Epitaxial van der Waals Quantum Solids, Institute for Basic Science (IBS), Pohang, Gyeongbuk, 37673, Republic of Korea
- Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, Gyeongbuk, 37673, Republic of Korea
| | - Min-Yeong Choi
- Center for Epitaxial van der Waals Quantum Solids, Institute for Basic Science (IBS), Pohang, Gyeongbuk, 37673, Republic of Korea
- Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, Gyeongbuk, 37673, Republic of Korea
| | - Cheol-Joo Kim
- Center for Epitaxial van der Waals Quantum Solids, Institute for Basic Science (IBS), Pohang, Gyeongbuk, 37673, Republic of Korea
- Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, Gyeongbuk, 37673, Republic of Korea
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6
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Effect of secondary bis-pyridine-bis-amide ligand on the construction of Zn-based coordination polymers and the enhancement of ultrasensitive luminescent sensing properties. J SOLID STATE CHEM 2022. [DOI: 10.1016/j.jssc.2022.123516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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7
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Wang K, Taniguchi T, Watanabe K, Xue J. Natural p-n Junctions at the MoS 2 Flake Edges. ACS APPLIED MATERIALS & INTERFACES 2022; 14:39039-39045. [PMID: 35984409 DOI: 10.1021/acsami.2c09457] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Two-dimensional (2D) semiconductors are holding promises as channel materials for field-effect transistors. Compared to traditional three-dimensional (3D) semiconductors whose electronic and optical properties are hindered by dangling bonds and trap states at the surfaces, 2D materials with saturated chemical bonds on the surface maintain the excellent properties even when device thickness scales down to monolayer. However, dangling bonds are unavoidable at their edges, which are often overlooked and should have important effects on the devices. Here, we show that the edges of as-exfoliated and etched MoS2 are naturally p-type doped and can form p-n junctions with the bulk of the flake. The width of these edge regions is around 20 nm. While their existence could present challenges for the shrinkage of devices, they can be exploited to form rectifying or optoelectronic devices based on a single flake of MoS2 without the need of an elaborate extrinsic doping process.
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Affiliation(s)
- Kang Wang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- University of Chinese Academy of Science, Beijing 100190, China
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba 305-004, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba 305-0044, Japan
| | - Jiamin Xue
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
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8
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Ripoll-Sau J, Calleja F, Casado Aguilar P, Ibarburu IM, Vázquez de Parga AL, Miranda R, Garnica M. Phase control and lateral heterostructures of MoTe 2 epitaxially grown on graphene/Ir(111). NANOSCALE 2022; 14:10880-10888. [PMID: 35848284 DOI: 10.1039/d2nr03074h] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Engineering the growth of the different phases of two-dimensional transition metal dichalcogenides (2D-TMDs) is a promising way to exploit their potential since the phase determines their physical and chemical properties. Here, we report on the epitaxial growth of monolayer MoTe2 on graphene on an Ir(111) substrate. Scanning tunneling microscopy and spectroscopy provide insights into the structural and electronic properties of the different polymorphic phases, which remain decoupled from the substrate due to the weak interaction with graphene. In addition, we demonstrate a great control of the relative coverage of the relevant 1T' and 1H MoTe2 phases by varying the substrate temperature during the growth. In particular, we obtain large areas of the 1T' phase exclusively or the coexistence of both phases with different ratios.
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Affiliation(s)
- Joan Ripoll-Sau
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), 28049 Madrid, Spain.
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Fabian Calleja
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), 28049 Madrid, Spain.
| | - Pablo Casado Aguilar
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), 28049 Madrid, Spain.
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Iván M Ibarburu
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), 28049 Madrid, Spain.
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Amadeo L Vázquez de Parga
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), 28049 Madrid, Spain.
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Instituto "Nicolás Cabrera", Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Rodolfo Miranda
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), 28049 Madrid, Spain.
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Instituto "Nicolás Cabrera", Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Manuela Garnica
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), 28049 Madrid, Spain.
- Instituto "Nicolás Cabrera", Universidad Autónoma de Madrid, 28049 Madrid, Spain
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9
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Di Bernardo I, Blyth J, Watson L, Xing K, Chen YH, Chen SY, Edmonds MT, Fuhrer MS. Defects, band bending and ionization rings in MoS 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:174002. [PMID: 35081526 DOI: 10.1088/1361-648x/ac4f1d] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 01/26/2022] [Indexed: 06/14/2023]
Abstract
Chalcogen vacancies in transition metal dichalcogenides are widely acknowledged as both donor dopants and as a source of disorder. The electronic structure of sulphur vacancies in MoS2however is still controversial, with discrepancies in the literature pertaining to the origin of the in-gap features observed via scanning tunneling spectroscopy (STS) on single sulphur vacancies. Here we use a combination of scanning tunnelling microscopy and STS to study embedded sulphur vacancies in bulk MoS2crystals. We observe spectroscopic features dispersing in real space and in energy, which we interpret as tip position- and bias-dependent ionization of the sulphur vacancy donor due to tip induced band bending. The observations indicate that care must be taken in interpreting defect spectra as reflecting in-gap density of states, and may explain discrepancies in the literature.
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Affiliation(s)
- Iolanda Di Bernardo
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
| | - James Blyth
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
| | - Liam Watson
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
| | - Kaijian Xing
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
| | - Yi-Hsun Chen
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
| | - Shao-Yu Chen
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
| | - Mark T Edmonds
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
- Monash Centre for Atomically Thin Materials, Monash University, Clayton, 3800, VIC, Australia
| | - Michael S Fuhrer
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
- Monash Centre for Atomically Thin Materials, Monash University, Clayton, 3800, VIC, Australia
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10
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Liu Y, Wang Y, Zhang XS, Sheng YS, Li WZ, Yang AA, Luan J, Liu HZ, Wang ZG. A novel 3D Zn-coordination polymer based on a multiresponsive fluorescent sensor demonstrating outstanding sensitivities and selectivities for the efficient detection of multiple analytes. Dalton Trans 2021; 50:15176-15186. [PMID: 34622902 DOI: 10.1039/d1dt02260a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A novel and unusual 3D luminescent coordination polymer (CP) [Zn2(3-bpah)(bpta)(H2O)]·3H2O (1), where 3-bpah denotes N,N'-bis(3-pyridinecarboxamide)-1,2-cyclohexane and H4bpta denotes 2,2',4,4'-biphenyltetracarboxylic acid, was successfully synthesized via hydrothermal methods from Zn(II) ions and 3-bpah and bpta ligands. The structure of this CP was investigated via powder X-ray diffraction (PXRD) analysis along with single crystal X-ray diffraction. Notably, 1 exhibits remarkable fluorescence behavior and stability over a wide pH range and in various pure organic solvents. More importantly, 1 can become an outstanding candidate for the selective and sensitive sensing of Fe3+, Mg2+, Cr2O72-, MnO4-, nitrobenzene (NB) and nitromethane (NM), at an extremely low detection limit. The changes in the fluorescence intensity exhibited by these six analytes in the presence of 1 over a wide pH range indicate that this polymer can be an excellent luminescent sensor. To the best of our knowledge, 1 is a rare example of a CP-based multiresponsive fluorescent sensor for metal cations, anions, and toxic organic solvents.
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Affiliation(s)
- Yu Liu
- College of Science, Shenyang University of Chemical Technology, Shenyang, 110142, P. R. China.
| | - Yan Wang
- College of Science, Shenyang University of Chemical Technology, Shenyang, 110142, P. R. China.
| | - Xiao-Sa Zhang
- College of Science, Shenyang University of Chemical Technology, Shenyang, 110142, P. R. China.
| | - Yu-Shu Sheng
- College of Science, Shenyang University of Chemical Technology, Shenyang, 110142, P. R. China.
| | - Wen-Ze Li
- College of Science, Shenyang University of Chemical Technology, Shenyang, 110142, P. R. China.
| | - Ai-Ai Yang
- College of Science, Shenyang University of Chemical Technology, Shenyang, 110142, P. R. China.
| | - Jian Luan
- College of Sciences, Northeastern University, Shenyang, 100819, P. R. China.
| | - Hong-Zhu Liu
- Post-Doctoral Research Station of Dalian Zhenbang Fluorocarbon Paint Stock Co., Ltd, Dalian, 116036, P. R. China
| | - Zhong-Gang Wang
- State Key Laboratory of fine Chemicals, Department of Polymer Science and Materials, School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, P. R. China
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11
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Pielić B, Novko D, Rakić IŠ, Cai J, Petrović M, Ohmann R, Vujičić N, Basletić M, Busse C, Kralj M. Electronic Structure of Quasi-Freestanding WS 2/MoS 2 Heterostructures. ACS APPLIED MATERIALS & INTERFACES 2021; 13:50552-50563. [PMID: 34661383 DOI: 10.1021/acsami.1c15412] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Growth of 2D materials under ultrahigh-vacuum (UHV) conditions allows for an in situ characterization of samples with direct spectroscopic insight. Heteroepitaxy of transition-metal dichalcogenides (TMDs) in UHV remains a challenge for integration of several different monolayers into new functional systems. In this work, we epitaxially grow lateral WS2-MoS2 and vertical WS2/MoS2 heterostructures on graphene. By means of scanning tunneling spectroscopy (STS), we first examined the electronic structure of monolayer MoS2, WS2, and WS2/MoS2 vertical heterostructure. Moreover, we investigate a band bending in the vicinity of the narrow one-dimensional (1D) interface of the WS2-MoS2 lateral heterostructure and mirror twin boundary (MTB) in the WS2/MoS2 vertical heterostructure. Density functional theory (DFT) is used for the calculation of the band structures, as well as for the density of states (DOS) maps at the interfaces. For the WS2-MoS2 lateral heterostructure, we confirm type-II band alignment and determine the corresponding depletion regions, charge densities, and the electric field at the interface. For the MTB, we observe a symmetric upward bend bending and relate it to the dielectric screening of graphene affecting dominantly the MoS2 layer. Quasi-freestanding heterostructures with sharp interfaces, large built-in electric field, and narrow depletion region widths are proper candidates for future designing of electronic and optoelectronic devices.
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Affiliation(s)
- Borna Pielić
- Center of Excellence for Advanced Materials and Sensing Devices, Institute of Physics, Bijenička cesta 46, 10000 Zagreb, Croatia
| | - Dino Novko
- Center of Excellence for Advanced Materials and Sensing Devices, Institute of Physics, Bijenička cesta 46, 10000 Zagreb, Croatia
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián, Spain
| | - Iva Šrut Rakić
- Center of Excellence for Advanced Materials and Sensing Devices, Institute of Physics, Bijenička cesta 46, 10000 Zagreb, Croatia
| | - Jiaqi Cai
- Department Physik, Universität Siegen, Walter-Flex-Str. 3, 57068 Siegen, Germany
| | - Marin Petrović
- Center of Excellence for Advanced Materials and Sensing Devices, Institute of Physics, Bijenička cesta 46, 10000 Zagreb, Croatia
| | - Robin Ohmann
- Department Physik, Universität Siegen, Walter-Flex-Str. 3, 57068 Siegen, Germany
| | - Nataša Vujičić
- Center of Excellence for Advanced Materials and Sensing Devices, Institute of Physics, Bijenička cesta 46, 10000 Zagreb, Croatia
| | - Mario Basletić
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb, Croatia
| | - Carsten Busse
- Department Physik, Universität Siegen, Walter-Flex-Str. 3, 57068 Siegen, Germany
| | - Marko Kralj
- Center of Excellence for Advanced Materials and Sensing Devices, Institute of Physics, Bijenička cesta 46, 10000 Zagreb, Croatia
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12
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Zhussupbekov K, Walshe K, Walls B, Ionov A, Bozhko SI, Ksenz A, Mozhchil RN, Zhussupbekova A, Fleischer K, Berman S, Zhilyaev I, O’Regan DD, Shvets IV. Surface Modification and Subsequent Fermi Density Enhancement of Bi(111). THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2021; 125:5549-5558. [PMID: 34276852 PMCID: PMC8279637 DOI: 10.1021/acs.jpcc.0c07345] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 02/24/2021] [Indexed: 06/13/2023]
Abstract
Defects introduced to the surface of Bi(111) break the translational symmetry and modify the surface states locally. We present a theoretical and experimental study of the 2D defects on the surface of Bi(111) and the states that they induce. Bi crystals cleaved in ultrahigh vacuum (UHV) at low temperature (110 K) and the resulting ion-etched surface are investigated by low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy (UPS), and scanning tunneling microscopy (STM) as well as spectroscopy (STS) techniques in combination with density functional theory (DFT) calculations. STS measurements of cleaved Bi(111) reveal that a commonly observed bilayer step edge has a lower density of states (DOS) around the Fermi level as compared to the atomic-flat terrace. Following ion bombardment, the Bi(111) surface reveals anomalous behavior at both 110 and 300 K: Surface periodicity is observed by LEED, and a significant increase in the number of bilayer step edges and energetically unfavorable monolayer steps is observed by STM. It is suggested that the newly exposed monolayer steps and the type A bilayer step edges result in an increase to the surface Fermi density as evidenced by UPS measurements and the Kohn-Sham DOS. These states appear to be thermodynamically stable under UHV conditions.
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Affiliation(s)
- Kuanysh Zhussupbekov
- School
of Physics and Centre for Research on Adaptive Nanostructures and
Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland
| | - Killian Walshe
- School
of Physics and Centre for Research on Adaptive Nanostructures and
Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland
| | - Brian Walls
- School
of Physics and Centre for Research on Adaptive Nanostructures and
Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland
| | - Andrei Ionov
- Institute
of Solid State Physics, Russian Academy
of Sciences, Chernogolovka, Russia
| | - Sergei I. Bozhko
- School
of Physics and Centre for Research on Adaptive Nanostructures and
Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland
- Institute
of Solid State Physics, Russian Academy
of Sciences, Chernogolovka, Russia
| | - Andrei Ksenz
- Institute
of Solid State Physics, Russian Academy
of Sciences, Chernogolovka, Russia
| | - Rais N. Mozhchil
- Institute
of Solid State Physics, Russian Academy
of Sciences, Chernogolovka, Russia
| | - Ainur Zhussupbekova
- School
of Physics and Centre for Research on Adaptive Nanostructures and
Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland
| | - Karsten Fleischer
- School
of Physics and Centre for Research on Adaptive Nanostructures and
Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland
- School
of Physical Sciences, Dublin City University, Dublin 9, Ireland
| | - Samuel Berman
- School
of Physics and Centre for Research on Adaptive Nanostructures and
Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland
| | - Ivan Zhilyaev
- Institute
of Microelectronics Technology and High Purity Materials, Russian Academy of Sciences, Chernogolovka, Russia
| | - David D. O’Regan
- School
of Physics and Centre for Research on Adaptive Nanostructures and
Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland
- AMBER,
the SFI Research Centre for Advanced Materials and BioEngineering
Research, Dublin 2, Ireland
| | - Igor V. Shvets
- School
of Physics and Centre for Research on Adaptive Nanostructures and
Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland
| |
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