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Qin T, Wang T, Zhu J. Recent progress in on-surface synthesis of nanoporous graphene materials. Commun Chem 2024; 7:154. [PMID: 38977754 PMCID: PMC11231364 DOI: 10.1038/s42004-024-01222-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Accepted: 06/07/2024] [Indexed: 07/10/2024] Open
Abstract
Nanoporous graphene (NPG) materials are generated by removing internal degree-3 vertices from graphene and introducing nanopores with specific topological structures, which have been widely explored and exploited for applications in electronic devices, membranes, and energy storage. The inherent properties of NPGs, such as the band structures, field effect mobilities and topological properties, are crucially determined by the geometric structure of nanopores. On-surface synthesis is an emerging strategy to fabricate low-dimensional carbon nanostructures with atomic precision. In this review, we introduce the progress of on-surface synthesis of atomically precise NPGs, and classify NPGs from the aspects of element types, topological structures, pore shapes, and synthesis strategies. We aim to provide a comprehensive overview of the recent advancements, promoting interdisciplinary collaboration to further advance the synthesis and applications of NPGs.
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Affiliation(s)
- Tianchen Qin
- Department of Pharmacy, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, and National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Tao Wang
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032, P. R. China.
| | - Junfa Zhu
- Department of Pharmacy, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, and National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, P. R. China.
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2
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Khatun S, Samanta S, Addicoat MA, Pradhan A. Bottom-Up Synthesis of Twisted Porous Graphene through a Heterogeneous Scholl Reaction and Its Supercapacitor Application. ACS APPLIED MATERIALS & INTERFACES 2024; 16:19877-19883. [PMID: 38570930 DOI: 10.1021/acsami.4c02762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/05/2024]
Abstract
Anthracene- and pyrene-based twisted porous graphene (AN-Pyre-PG) with an ordered pore structure has been synthesized through bottom-up solution phase synthesis from a conjugated microporous polymer (AN-Pyre-CMP) via a heterogeneous Scholl cyclization reaction. The regular-ordered pores embedded within the graphene structures were analyzed through a Raman spectrum, different morphological analyses, and theoretical studies. A significant change in surface area from AN-Pyre-CMP to AN-Pyre-PG was observed, from 143 to 640 m2/g, respectively. Surface area-driven capacitive properties were also observed. Twisted-structure and ordered porous graphene shows better specific capacitance compared to CMP. AN-Pyre-PG shows a specific capacitance of 629 F g-1 at 1 A g-1, with 91% retention of capacitance after 3000 charge-discharge cycles, whereas AN-Pyre-CMP shows a maximum specific capacitance of 200 F g-1 was observed at 2 A g-1.
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Affiliation(s)
- Sahina Khatun
- Department of Chemistry, Birla Institute of Technology (BIT) - Mesra, Ranchi, Jharkhand 835215, India
| | - Siddhartha Samanta
- Department of Chemistry, Birla Institute of Technology (BIT) - Mesra, Ranchi, Jharkhand 835215, India
| | - Matthew A Addicoat
- School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, U.K
| | - Anirban Pradhan
- Department of Chemistry, Birla Institute of Technology (BIT) - Mesra, Ranchi, Jharkhand 835215, India
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3
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Piquero-Zulaica I, Corral-Rascón E, Diaz de Cerio X, Riss A, Yang B, Garcia-Lekue A, Kher-Elden MA, Abd El-Fattah ZM, Nobusue S, Kojima T, Seufert K, Sakaguchi H, Auwärter W, Barth JV. Deceptive orbital confinement at edges and pores of carbon-based 1D and 2D nanoarchitectures. Nat Commun 2024; 15:1062. [PMID: 38316774 PMCID: PMC10844643 DOI: 10.1038/s41467-024-45138-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 01/15/2024] [Indexed: 02/07/2024] Open
Abstract
The electronic structure defines the properties of graphene-based nanomaterials. Scanning tunneling microscopy/spectroscopy (STM/STS) experiments on graphene nanoribbons (GNRs), nanographenes, and nanoporous graphene (NPG) often determine an apparent electronic orbital confinement into the edges and nanopores, leading to dubious interpretations such as image potential states or super-atom molecular orbitals. We show that these measurements are subject to a wave function decay into the vacuum that masks the undisturbed electronic orbital shape. We use Au(111)-supported semiconducting gulf-type GNRs and NPGs as model systems fostering frontier orbitals that appear confined along the edges and nanopores in STS measurements. DFT calculations confirm that these states originate from valence and conduction bands. The deceptive electronic orbital confinement observed is caused by a loss of Fourier components, corresponding to states of high momentum. This effect can be generalized to other 1D and 2D carbon-based nanoarchitectures and is important for their use in catalysis and sensing applications.
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Affiliation(s)
- Ignacio Piquero-Zulaica
- Physics Department E20, TUM School of Natural Sciences, Technical University of Munich, James-Franck-Straße 1, D-85748, Garching, Germany.
| | - Eduardo Corral-Rascón
- Physics Department E20, TUM School of Natural Sciences, Technical University of Munich, James-Franck-Straße 1, D-85748, Garching, Germany
| | - Xabier Diaz de Cerio
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, E-20018, Donostia-San Sebastian, Spain
| | - Alexander Riss
- Physics Department E20, TUM School of Natural Sciences, Technical University of Munich, James-Franck-Straße 1, D-85748, Garching, Germany.
| | - Biao Yang
- Physics Department E20, TUM School of Natural Sciences, Technical University of Munich, James-Franck-Straße 1, D-85748, Garching, Germany
| | - Aran Garcia-Lekue
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, E-20018, Donostia-San Sebastian, Spain.
- Ikerbasque, Basque Foundation for Science, 48013, Bilbao, Spain.
| | - Mohammad A Kher-Elden
- Physics Department, Faculty of Science, Al-Azhar University, Nasr City, E-11884, Cairo, Egypt
| | - Zakaria M Abd El-Fattah
- Physics Department, Faculty of Science, Al-Azhar University, Nasr City, E-11884, Cairo, Egypt
| | - Shunpei Nobusue
- Institute of Advanced Energy, Kyoto University, Uji, 611-0011, Kyoto, Japan
| | - Takahiro Kojima
- Institute of Advanced Energy, Kyoto University, Uji, 611-0011, Kyoto, Japan
| | - Knud Seufert
- Physics Department E20, TUM School of Natural Sciences, Technical University of Munich, James-Franck-Straße 1, D-85748, Garching, Germany
| | - Hiroshi Sakaguchi
- Institute of Advanced Energy, Kyoto University, Uji, 611-0011, Kyoto, Japan.
| | - Willi Auwärter
- Physics Department E20, TUM School of Natural Sciences, Technical University of Munich, James-Franck-Straße 1, D-85748, Garching, Germany
| | - Johannes V Barth
- Physics Department E20, TUM School of Natural Sciences, Technical University of Munich, James-Franck-Straße 1, D-85748, Garching, Germany
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Chen A, Tong H, Wu CW, Li SY, Jia PZ, Zhou WX. First-principles prediction of the thermal conductivity of two configurations of difluorinated graphene monolayer. Phys Chem Chem Phys 2023; 26:421-429. [PMID: 38078535 DOI: 10.1039/d3cp04923j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
Lattice thermal conductivity (κL) plays a crucial role in the thermal management of electronic devices. In this study, we systematically investigate the thermal transport properties of monolayer fluorinated graphene using a combination of machine learning-based interatomic potentials and the phonon Boltzmann transport equation. At a temperature of 300 K, we find that the κL values for chair-configured fluorinated graphene monolayers are 184.24 W m-1 K-1 in the zigzag direction and 205.57 W m-1 K-1 in the armchair direction. For the boat configuration, the κL values are 120.45 W m-1 K-1 and 64.26 W m-1 K-1 in the respective directions. The disparities in κL between these two configurations predominantly stem from differences in phonon relaxation times, which can be elucidated by examining the Grüneisen parameters representing the degree of anharmonicity. A more in-depth analysis of bond strengths, as assessed by the crystal orbital Hamiltonian population, reveals that the stronger in-plane CC bonds in chair-configured fluorinated graphene monolayers are the primary contributors to the observed variations in anharmonicity.
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Affiliation(s)
- Ao Chen
- School of Materials Science and Engineering & Hunan Provincial Key Laboratory of Advanced Materials for New Energy Storage and Conversion, Hunan University of Science and Technology, Xiangtan 411201, China.
| | - Hua Tong
- School of Materials Science and Engineering & Hunan Provincial Key Laboratory of Advanced Materials for New Energy Storage and Conversion, Hunan University of Science and Technology, Xiangtan 411201, China.
| | - Cheng-Wei Wu
- School of Materials Science and Engineering & Hunan Provincial Key Laboratory of Advanced Materials for New Energy Storage and Conversion, Hunan University of Science and Technology, Xiangtan 411201, China.
| | - Shi-Yi Li
- School of Materials Science and Engineering & Hunan Provincial Key Laboratory of Advanced Materials for New Energy Storage and Conversion, Hunan University of Science and Technology, Xiangtan 411201, China.
| | - Pin-Zhen Jia
- School of Science, Hunan Institute of Technology, Hengyang 421002, China.
| | - Wu-Xing Zhou
- School of Materials Science and Engineering & Hunan Provincial Key Laboratory of Advanced Materials for New Energy Storage and Conversion, Hunan University of Science and Technology, Xiangtan 411201, China.
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5
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Qin T, Guo D, Xiong J, Li X, Hu L, Yang W, Chen Z, Wu Y, Ding H, Hu J, Xu Q, Wang T, Zhu J. Synthesis of a Porous [14]Annulene Graphene Nanoribbon and a Porous [30]Annulene Graphene Nanosheet on Metal Surfaces. Angew Chem Int Ed Engl 2023; 62:e202306368. [PMID: 37401637 DOI: 10.1002/anie.202306368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 07/03/2023] [Accepted: 07/04/2023] [Indexed: 07/05/2023]
Abstract
The electrical and mechanical properties of graphene-based materials can be tuned by the introduction of nanopores, which are sensitively related to the size, morphology, density, and location of nanopores. The synthesis of low-dimensional graphene nanostructures containing well-defined nonplanar nanopores has been challenging due to the intrinsic steric hindrance. Herein, we report the selective synthesis of one-dimensional (1D) graphene nanoribbons (GNRs) containing periodic nonplanar [14]annulene pores on Ag(111) and two-dimensional (2D) porous graphene nanosheet containing periodic nonplanar [30]annulene pores on Au(111), starting from a same precursor. The formation of distinct products on the two substrates originates from the different thermodynamics and kinetics of coupling reactions. The reaction mechanisms were confirmed by a series of control experiments, and the appropriate thermodynamic and kinetic parameters for optimizing the reaction pathways were proposed. In addition, the combined scanning tunneling spectroscopy (STS) and density functional theory (DFT) calculations revealed the electronic structures of porous graphene structures, demonstrating the impact of nonplanar pores on the π-conjugation of molecules.
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Affiliation(s)
- Tianchen Qin
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Dezhou Guo
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Juanjuan Xiong
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Xingyu Li
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Lei Hu
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Weishan Yang
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Zijie Chen
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Yulun Wu
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Honghe Ding
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Jun Hu
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Qian Xu
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Tao Wang
- Donostia International Physics Center, 20018, San Sebastián, Spain
| | - Junfa Zhu
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
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6
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Lu Y, Yan L, Fu H, Song Y, Cao Y, Li S, Du R, Li J, Fu Z, Zhang Z. Size-tunable energy gaps of hydrogen-terminated biphenylene segments. Phys Chem Chem Phys 2023; 25:23879-23884. [PMID: 37642273 DOI: 10.1039/d3cp03666a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
The electronic properties of hydrogen-terminated biphenylene (BP) segments of different sizes on the sub-nanoscale are explored using density functional theory, and the size dependence of the energy gap is evaluated using a structural parameter as a function of the bond lengths and the electronic density contributions. More importantly, the energy gap is observed to decrease linearly with the reduced hydrogen-to-carbon ratio of the corresponding structures, while the decrease-rate undergoes a diminution of four times at a gap of 0.5 eV due to the transformed distribution of the lowest unoccupied molecular orbital. The results give a deep insight into the size-tunable energy gaps of BPs and provide a possibility for the preparation of hydrogen-terminated carbon materials with a desirable energy gap.
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Affiliation(s)
- Yirui Lu
- School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, Shaanxi, China.
| | - Lei Yan
- School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, Shaanxi, China.
| | - Huixia Fu
- Center of Quantum Materials and Devices, College of Physics, Chongqing University, Chongqing 401331, China.
| | - Yuhui Song
- School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, Shaanxi, China.
| | - Yifei Cao
- School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, Shaanxi, China.
| | - Sen Li
- School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, Shaanxi, China.
| | - Ruhai Du
- School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, Shaanxi, China.
| | - Jinping Li
- School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, Shaanxi, China.
| | - Zhengkun Fu
- School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, Shaanxi, China.
| | - Zhenglong Zhang
- School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, Shaanxi, China.
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7
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Lu Y, Yan L, Huang S, Zhou X, Zhang M, Du R, Zhang Z. Localized vibrational characteristics of biphenylene strips resulting in length-dependent Raman spectra. Phys Chem Chem Phys 2023; 25:22505-22511. [PMID: 37581352 DOI: 10.1039/d3cp01885g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
The length dependence of the Raman spectra and vibrational properties of biphenylene strips are explored using density functional theory. The Raman intensity of two bands increases and decreases with length due to the enlarging and shrinking of the proportion of effective vibrating units. The red shift of vibrational modes is observed with the increase in length, owing to the various vibrational characteristics of the effective vibrating units. More importantly, a linear relationship between the energy gap and the wavenumber of the shifting Raman bands is obtained. The results allow us to interpret the length-dependence of the Raman spectra from the perspective of localized vibrational characteristics and suggest that Raman spectroscopy can be used as a convenient method to determine the energy gap of nanomaterials.
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Affiliation(s)
- Yirui Lu
- School of physics and information technology, Shaanxi Normal University, Shaanxi, Xi'an 710119, China.
| | - Lei Yan
- School of physics and information technology, Shaanxi Normal University, Shaanxi, Xi'an 710119, China.
| | - Sichen Huang
- School of physics and information technology, Shaanxi Normal University, Shaanxi, Xi'an 710119, China.
| | - Xilin Zhou
- School of physics and information technology, Shaanxi Normal University, Shaanxi, Xi'an 710119, China.
| | - Min Zhang
- School of physics and information technology, Shaanxi Normal University, Shaanxi, Xi'an 710119, China.
| | - Ruhai Du
- School of physics and information technology, Shaanxi Normal University, Shaanxi, Xi'an 710119, China.
| | - Zhenglong Zhang
- School of physics and information technology, Shaanxi Normal University, Shaanxi, Xi'an 710119, China.
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Kausar A. Nanoporous graphene in polymeric nanocomposite membranes for gas separation and water purification—standings and headways. JOURNAL OF MACROMOLECULAR SCIENCE PART A-PURE AND APPLIED CHEMISTRY 2023. [DOI: 10.1080/10601325.2023.2177170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Affiliation(s)
- Ayesha Kausar
- NPU-NCP Joint International Research Center on Advanced Nanomaterials and Defects Engineering, National Centre for Physics, Islamabad, Pakistan
- NPU-NCP Joint International Research Center on Advanced Nanomaterials and Defects Engineering, Northwestern Polytechnical University, Xi’an, China
- UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, iThemba LABS, Somerset West, South Africa
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9
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Wang D, Wang Z, Liu W, Zhong S, Feng YP, Loh KP, Wee ATS. Real-Space Investigation of the Multiple Halogen Bonds by Ultrahigh-Resolution Scanning Probe Microscopy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2202368. [PMID: 35719029 DOI: 10.1002/smll.202202368] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Indexed: 06/15/2023]
Abstract
The chemical bond is of central interest in chemistry, and it is of significance to study the nature of intermolecular bonds in real-space. Herein, non-contact atomic force microscopy (nc-AFM) and low-temperature scanning tunneling microscopy (LT-STM) are employed to acquire real-space atomic information of molecular clusters, i.e., monomer, dimer, trimer, tetramer, formed on Au(111). The formation of the various molecular clusters is due to the diversity of halogen bonds. DFT calculation also suggests the formation of three distinct halogen bonds among the molecular clusters, which originates from the noncovalent interactions of Br-atoms with the positive potential H-atoms, neutral potential Br-atoms, and negative potential N-atoms, respectively. This work demonstrates the real-space investigation of the multiple halogen bonds by nc-AFM/LT-STM, indicating the potential use of this technique to study other intermolecular bonds and to understand complex supramolecular assemblies at the atomic/sub-molecular level.
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Affiliation(s)
- Dingguan Wang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Zishen Wang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Wei Liu
- School of Physics, Southeast University, 2 Southeast University Road, Nanjing, China
| | - Siying Zhong
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Yuan Ping Feng
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Kian Ping Loh
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
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10
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Wang D, Lu X, Cai L, Zhang L, Feng S, Zhang W, Yang M, Wu J, Wang Z, Wee ATS. Low-Dimensional Porous Carbon Networks Using Single-/Triple-Coupling Polycyclic Hydrocarbon Precursors. ACS NANO 2022; 16:9843-9851. [PMID: 35657207 DOI: 10.1021/acsnano.2c03909] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Polycyclic hydrocarbons (PHs) share the same hexagonal structure of sp2 carbons as graphene but possess an energy gap due to quantum confinement effect. PHs can be synthesized by a bottom-up strategy starting from small building blocks covalently bonded into large 2D organic sheets. Further investigation of the role of the covalent bonding/coupling ways on their electronic properties is needed. Here, we demonstrate a surface-mediated synthesis of hexa-peri-hexabenzocoronene (HBC) and its extended HBC oligomers (dimers, trimers, and tetramers) via single- and triple-coupling ways and reveal the implication of different covalent bonding on their electronic properties. High-resolution low-temperature scanning tunneling microscopy and noncontact atomic force microscopy are employed to in situ determine the atomic structures of as-synthesized HBC oligomers. Scanning tunneling spectroscopy measurements show that the length extension of HBC oligomers narrows the energy gap between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). Furthermore, the energy gaps of triple-coupling HBC oligomers are smaller and decrease more significantly than that of the single-coupling ones. We hypothesize that the triple coupling promotes a more effective delocalization of π-electrons than the single coupling, according to density functional theory calculations. We also demonstrate that the HBC oligomers can further extend across the substrate steps to achieve conjugated polymers and large-area porous carbon networks.
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Affiliation(s)
- Dingguan Wang
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Xuefeng Lu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
- Department of Materials Science, Fudan University, Shanghai 200438, China
| | - Liangliang Cai
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Lei Zhang
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Shuo Feng
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
| | - Wenjing Zhang
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
| | - Ming Yang
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Jishan Wu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Zhuo Wang
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
| | - Andrew T S Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
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