Topological two-dimensional polymers

Springer, Maximilian A.; Liu, Tsai-Jung; Kuc, Agnieszka; Heine, Thomas

doi:10.1039/c9cs00893d

Cited by 112 publications

(104 citation statements)

References 54 publications

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“…In this sense, theoretical calculations are found to be very useful to predict or rationalize the relationships between chemical structural modifications and the properties of the resulting materials. DFT calculations on the electronic structures of different 2D conjugated polymers have been previously reported, with an emphasis on the role played by the network topology, [29][30][31] lattice symmetry 32 or structural differences between 1D and 2D, [33][34][35] among other structural factors. [36][37][38][39] However, while isolated truxene-based molecules have been amply theoretically explored, a systematic study of their 2D conjugated polymers has not yet been reported.…”

Section: Introductionmentioning

confidence: 99%

In silico design of 2D polymers containing truxene-based platforms: insights into their structural and electronic properties

et al. 2020

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Section: Introductionmentioning

confidence: 99%

In silico design of 2D polymers containing truxene-based platforms: insights into their structural and electronic properties

et al. 2020

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“…We noticed that many 2D COFs with C3 symmetry form Kagome lattice, such as N3-COF mentioned earlier, and they display flat bands near the Fermi level arising from non-bonded states, which are adverse to the in-plane charge transport and will increase the effective mass of excitons as well. [43][44] Instead, COFs in Lieb lattice with C2 symmetry constructed by four-arm nodes lack flat bands near the Fermi level (Figure S1), and the effective mass of charge carriers and excitons is reduced and further modulated by tailoring chemical building blocks of COFs. Besides, D-A design usually leads to space-separated electrons and holes, namely enlarged exciton radius, so we propose to design conjugated D-A COFs in Lieb lattice utilizing donor unit as node and acceptor unit as edge, which will reduce not only band gaps but also exciton binding energies of COFs.…”

Section: Understanding Photoelectrochemical Processes In Cof-based Photocatalysts For Efficient Water Splittingmentioning

confidence: 99%

“…When node units with C3 symmetry are used to construct COFs in Kagome lattice, flat bands typically appear at the VBM or CBM (Figure S1 and Figure S21). [43][44] These flat bands are formed by non-bonding orbitals of node and edge units and have very large effective mass of electron or hole, which could lead to intriguing magnetic phenomenon but is not desired for high-performance charge transport. 43 Since the effective mass of exciton could be defined as 1/m * =1/me * +1/mh * , 42 where me * and mh * stand for the effective mass of electron and hole respectively, the flat band at VBM or CBM could also give rise to large exciton mass and binding energy.…”

Section: Modulating Band Gaps and Band Edge Energies In Cofs For Overall Water Splitting Under Visible Lightmentioning

confidence: 99%

Covalent organic frameworks in Lieb lattice for tunable photocatalytic water splitting under visible light

Yu¹,

Wang²

2021

Preprint

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Photocatalytic water splitting is a promising solution to sustainable hydrogen production. Recently, conjugated covalent organic frameworks (COFs) with highly designable skeleton and inherent pores have emerged as promising photocatalysts for water splitting. However, structure-property relationships in COFs have not been established and the rational design of COFs with suitable electronic properties and chemical structures for water splitting is challenging. In this work, we proposed a facile strategy that is based on tailoring donor (D) and acceptor (A) building blocks of COFs in Lieb lattice, to achieve visible light absorption, prompt exciton dissociation, and metal-free hydrogen evolution. We constructed eight fully conjugated D-A COFs with a pyrene donor node and different acceptor edges linked by C=C and demonstrated that as compared to the D-D COF, D-A design not only shifted optical absorption to the visible and near-infrared region, but also modified band alignment to trigger overall water splitting. Moreover, the charge-transfer excitation in D-A COFs produced space-separated electrons and holes, and the exciton binding energy was substantially reduced due to increased dielectric screening in D-A COFs. Further, we found that the overpotential for hydrogen evolution reaction was suppressed by introducing hydrogen bond interactions in the hydrogen adsorption intermediate to enable metal-free catalysis. Finally, we attained five D-A COFs capable of visible-light-driven hydrogen production in neutral solution without the load of metal co-catalysts. These findings highlight a new route to design COF-photocatalysts and offer tremendous opportunities for regulating COFs towards efficient photocatalytic water splitting and other chemical transformations.

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“…During the two recent decades, profound new schemes of carbon nanostructures have been uncovered. [ 1 ] Carbon‐based systems range from C60 to single‐wall carbon nanotubes, and from graphite to graphene. [ 2–4 ] Technological properties of these materials are promising, they also exhibit different kinds of allotropes in each dimension: a (0D) fullerene molecule, (1D) nanotubes, (2D) graphene nanoribbons, and (3D) diamond.…”

Section: Introductionmentioning

confidence: 99%

Impact of Topological Edge Defects on Spin Transport Properties of Zigzag Graphene Nanoribbons

Sharifian

Ghasemifard

Taghizade

et al. 2021

Physica Status Solidi (b)

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Herein, the spin‐dependent transport properties of a zigzag graphene nanoribbon (zGNR) with edges decorated with a fluoranthene group are studied. Atomically perfect zigzag edge, including phenyl‐edge functionalization, was synthesized by Ruffieux et al. in a bottom‐up chemical technique. By performing nearest‐neighbor tight‐binding model in combination with Landauer formalism and Green's function approach, as well as considering Coulomb electronic interaction computed both with density functional calculations and mean‐field approximation of the Hubbard model, the magnetic and spin‐resolved transmissions are studied. Both the model Hamiltonian and density functional theory (DFT) descriptions yield very similar results. Importantly, by generating a special supercell, three different antiferromagnetic alignments for phenyl‐edge zGNR have been calculated, which was not developed in previous studies. The results show that by adding pentagon rings on both sides of the zGNR, the conductance loses its step‐like behavior. Our structure of interest is a semiconductor with a transport gap of 0.56 eV. This kind of defective structure will enable the spin‐feature characteristic, such as spin filtering, and add the spin degree of freedom to graphene‐based logic devices.

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Topological two-dimensional polymers

Abstract: The structural topology of a 2D network defines its electronic structure.

Cited by 112 publications

References 54 publications

In silico design of 2D polymers containing truxene-based platforms: insights into their structural and electronic properties

In silico design of 2D polymers containing truxene-based platforms: insights into their structural and electronic properties

Covalent organic frameworks in Lieb lattice for tunable photocatalytic water splitting under visible light

Impact of Topological Edge Defects on Spin Transport Properties of Zigzag Graphene Nanoribbons

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