MXene Derived Metal–Organic Frameworks

Wu, Hao; Almalki, Maram; Xu, Xiangming; Lei, Yongjiu; Ming, Fangwang; Mallick, Arijit; Roddatis, Vladimir; Lopatin, Sergei; Shekhah, Osama; Eddaoudi, Mohamed; Alshareef, Husam N.

doi:10.1021/jacs.9b11446

Cited by 138 publications

(90 citation statements)

References 52 publications

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“…Thus, based on the use of DDEC cameras, this set of methods further advanced the atomic-resolution TEM imaging of MOFs and other beam- Recently, Wu et al synthesized porphyrin-based MOF nanosheets using MXene V 2 CT x (T = F, O, and OH) as a metal precursor; they successfully acquired HR-TEM images for these nanosheets with a DDEC camera. The obtained near-atomicresolution images revealed highly ordered cages, which were in good agreement with the proposed crystal structure and simulated images 60 .…”

Section: High-resolution Electron Imaging Of Mofssupporting

confidence: 86%

Bulk and local structures of metal–organic frameworks unravelled by high-resolution electron microscopy

et al. 2020

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The periodic bulk structures of metal-organic frameworks (MOFs) can be solved by diffraction-based techniques; however, their non-periodic local structures-such as crystal surfaces, grain boundaries, defects, and guest molecules-have long been elusive due to a lack of suitable characterization tools. Recent advances in (scanning) transmission electron microscopy ((S)TEM) has made it possible to probe the local structures of MOFs at atomic resolution. In this article, we discuss why high-resolution (S)TEM of MOFs is challenging and how the new low-dose techniques overcome this challenge, and we review various MOF structural features observed by (S)TEM and important insights gained from these observations. Our discussions focus on real-space imaging, excluding other TEM-related characterization techniques (e.g. electron diffraction and spectroscopy). M etal-organic frameworks (MOFs) comprise metal centres/clusters with organic coordinating ligands and are characterized by their designable topologies, porosity, and functionalities 1,2. Studies on the structure-property relationship of MOFs are mainly based on their periodic crystallographic structures solved by diffraction-based techniques. In fact, the local non-periodic structures of MOFs-such as crystal surfaces, boundaries/interfaces, guest molecules, and point or extended defects-also have important effects on the properties of mass transport, sorption, and catalysis; for example, defects and interfaces severely affect how MOF membranes separate gases 3,4. However, probing local structures in MOF crystals with high spatial resolution is difficult, which poses a challenge to establishing a correlation between the properties of a MOF and its local structures with atomic precision. High-resolution transmission electron microscopy (HR-TEM) is the most widely used tool for imaging non-periodic local structures of crystalline materials, which are invisible in diffraction 5,6. Unfortunately, MOFs are extremely sensitive to the electron beam irradiation and their structures can be easily damaged during HR-TEM imaging 7-9. In fact, high-resolution

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Section: High-resolution Electron Imaging Of Mofssupporting

confidence: 86%

Bulk and local structures of metal–organic frameworks unravelled by high-resolution electron microscopy

et al. 2020

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“…Nanosizing MOFs into ultrathin metal-organic layers (MOLs) can e ciently accelerate mass transport / electron transfer and create abundant readily accessible active sites to ensure high activity in various catalytic reactions. [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] Moreover, ultrathin MOFs with limited number of atoms represent ideal models to explore structure-performance relationships for further rationally constructing e cient catalysts at atomic/molecular levels. For example, a mono-carboxylic bipyridine ligand was utilized to assemble Re-/Mn-Ru molecules into monolayer Hf-based MOLs, 20 the resulting Re-Ru-based MOLs can sustainably reduce CO 2 to CO under real sunlight for one week.…”

Section: Introductionmentioning

confidence: 99%

Facile electron delivery from graphene template to ultrathin metal-organic layers for boosting CO2 photoreduction

Wang¹,

Qiao

Nie³

et al. 2020

Preprint

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Metal-organic layers (MOLs) with ordered structure and molecular tunability are of great potential as heterogeneous catalysts due to their readily accessible active sites. Herein, we demonstrate a facile template strategy to prepare MOLs with a uniform thickness of three metal coordination layers (ca. 1.5 nm) with graphene oxide (GO) as both template and electron mediator. The resulting MOL@GO exhibits an outstanding performance for CO2 photoreduction with a record-high total CO yield of 3133 mmol/gMOL among all the metal-organic framework and MOL catalysts (CO selectivity of 95%). This performance is ca. 34 times higher than that of bulky Co-MOF, [CoL(H2O)2]•0.5H2O (H2L = 5-(1H-1,2,4-triazol-1-yl)isophthalic acid). Systematic studies reveal that well exposed active sites in MOLs, and facile electron transfer between heterogeneous and homogeneous components mediated by GO, greatly contribute to its high activity. This work highlights a facile way for constructing ultrathin MOLs and demonstrate charge transfer pathway between conductive template and catalyst for boosting photocatalysis.

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“… 26 The proton transport of the acid-doped MX-MOF film was shown to follow the Grotthus mechanism in our previous report. 26 Figure 3 b schematically displays the hydrogen-bonding network formed between the MX-MOF nanosheets and H 3 PO 4 , which enables proton transport. The increased proton conductivity in a higher humidity environment results from the higher concentration of water molecules inside the hydrogen-bonding network, which could further reduce the barrier for proton movement, as illustrated in Figure 3 c.…”

Section: Resultsmentioning

confidence: 70%

“…V 2 CT x MXene was prepared according to the literature. 26 In detail, 1 g of V 2 AlC MAX (300 mesh) was added slowly into 20 mL of high-concentrated hydrogen fluoride and stirred at 35 °C for 24 h. Then, the mixed solution was centrifuged (3000 rpm) to collect the sediment, which was washed repeatedly with deionized (DI) water until the pH of the supernatant reaches ∼6. Next, 10 mL of tetramethylammonium hydroxide (TMAOH, 1 M) was added in the sediment and stirred for 4 h at room temperature.…”

Section: Methodsmentioning

confidence: 99%

Iontronics Using V₂CT_x MXene-Derived Metal–Organic Framework Solid Electrolytes

et al. 2020

ACS Nano

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Electronic applications of porous metal–organic frameworks (MOFs) have recently emerged as an important research area. However, there is still no report on using MOF solid electrolytes in iontronics, which could take advantage of the porous feature of MOFs in the ionic transport. In this article, MXene-derived two-dimensional porphyrinic MOF (MX-MOF) films are demonstrated as an electronic-grade proton-conducting electrolyte. Meanwhile, the MX-MOF film shows high quality, chemical stability, and capability of standard device patterning processes ( e . g ., dry etching and optical and electron beam lithography). Using the commercialized nanofabrication processes, an electric double-layer (EDL) transistor is demonstrated using the MX-MOF film (derived from V 2 CT x MXene) as an ionic gate and MoS 2 film as a semiconducting channel layer. The EDL transistor, operated by applying an electric field to control the interaction between ions and electrons, is the core device platform in the emerging iontronics field. Therefore, The MX-MOF, confirmed as a solid electrolyte for EDL transistor devices, could have a significant impact on iontronics research and development.

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MXene Derived Metal–Organic Frameworks

Cited by 138 publications

References 52 publications

Bulk and local structures of metal–organic frameworks unravelled by high-resolution electron microscopy

Bulk and local structures of metal–organic frameworks unravelled by high-resolution electron microscopy

Facile electron delivery from graphene template to ultrathin metal-organic layers for boosting CO2 photoreduction

Iontronics Using V₂CT_x MXene-Derived Metal–Organic Framework Solid Electrolytes

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MXene Derived Metal–Organic Frameworks

Cited by 138 publications

References 52 publications

Bulk and local structures of metal–organic frameworks unravelled by high-resolution electron microscopy

Bulk and local structures of metal–organic frameworks unravelled by high-resolution electron microscopy

Facile electron delivery from graphene template to ultrathin metal-organic layers for boosting CO2 photoreduction

Iontronics Using V2CTx MXene-Derived Metal–Organic Framework Solid Electrolytes

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Iontronics Using V₂CT_x MXene-Derived Metal–Organic Framework Solid Electrolytes