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Dive into the research topics where Donghun Kim is active.

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Featured researches published by Donghun Kim.


Nature | 2017

Ultra-selective high-flux membranes from directly synthesized zeolite nanosheets

Mi Young Jeon; Donghun Kim; Prashant Kumar; Pyung Soo Lee; Neel Rangnekar; Peng Bai; Meera Shete; Bahman Elyassi; Han Seung Lee; Katabathini Narasimharao; Sulaiman Nasir Basahel; Shaeel A. Al-Thabaiti; Wenqian Xu; Hong Je Cho; Evgenii O. Fetisov; Raghuram Thyagarajan; Robert F. DeJaco; Wei Fan; K. Andre Mkhoyan; J. Ilja Siepmann; Michael Tsapatsis

A zeolite with structure type MFI is an aluminosilicate or silicate material that has a three-dimensionally connected pore network, which enables molecular recognition in the size range 0.5–0.6 nm. These micropore dimensions are relevant for many valuable chemical intermediates, and therefore MFI-type zeolites are widely used in the chemical industry as selective catalysts or adsorbents. As with all zeolites, strategies to tailor them for specific applications include controlling their crystal size and shape. Nanometre-thick MFI crystals (nanosheets) have been introduced in pillared and self-pillared (intergrown) architectures, offering improved mass-transfer characteristics for certain adsorption and catalysis applications. Moreover, single (non-intergrown and non-layered) nanosheets have been used to prepare thin membranes that could be used to improve the energy efficiency of separation processes. However, until now, single MFI nanosheets have been prepared using a multi-step approach based on the exfoliation of layered MFI, followed by centrifugation to remove non-exfoliated particles. This top-down method is time-consuming, costly and low-yield and it produces fragmented nanosheets with submicrometre lateral dimensions. Alternatively, direct (bottom-up) synthesis could produce high-aspect-ratio zeolite nanosheets, with improved yield and at lower cost. Here we use a nanocrystal-seeded growth method triggered by a single rotational intergrowth to synthesize high-aspect-ratio MFI nanosheets with a thickness of 5 nanometres (2.5 unit cells). These high-aspect-ratio nanosheets allow the fabrication of thin and defect-free coatings that effectively cover porous substrates. These coatings can be intergrown to produce high-flux and ultra-selective MFI membranes that compare favourably with other MFI membranes prepared from existing MFI materials (such as exfoliated nanosheets or nanocrystals).


Angewandte Chemie | 2017

Nanoscale Control of Homoepitaxial Growth on a Two-Dimensional Zeolite

Meera Shete; Manjesh Kumar; Donghun Kim; Neel Rangnekar; Dandan Xu; Berna Topuz; Kumar Varoon Agrawal; E. Karapetrova; Benjamin L. Stottrup; Shaeel A. Al-Thabaiti; Sulaiman N. Basahel; Katabathini Narasimharao; Jeffrey D. Rimer; Michael Tsapatsis

Nanoscale crystal growth control is crucial for tailoring two-dimensional (2D) zeolites (crystallites with thickness less than two unit cells) and thicker zeolite nanosheets for applications in separation membranes and as hierarchical catalysts. However, methods to control zeolite crystal growth with nanometer precision are still in their infancy. Herein, we report solution-based growth conditions leading to anisotropic epitaxial growth of 2D zeolites with rates as low as few nanometers per day. Contributions from misoriented surface nucleation and rotational intergrowths are eliminated. Growth monitoring at the single-unit-cell level reveals novel nanoscale crystal-growth phenomena associated with the lateral size and surface curvature of 2D zeolites.


Angewandte Chemie | 2018

para‐Xylene Ultra‐selective Zeolite MFI Membranes Fabricated from Nanosheet Monolayers at the Air–Water Interface

Donghun Kim; Mi Young Jeon; Benjamin L. Stottrup; Michael Tsapatsis

The control of membrane morphology and microstructure is crucial to improve the separation performance of molecular-sieve membranes. This can be enabled by making thin, dense, and uniform seed-crystal coatings, which are then intergrown into continuous membranes. Herein, we show a novel and simple floating particle coating method can give closely packed monolayers of zeolite nanosheets on nonporous or porous supports. The zeolite nanosheet monolayer is formed at the air-water interface in a conical Teflon trough. As the water in the trough is drained, the monolayer is deposited on a support placed below. Membranes prepared by gel-free secondary growth of the nanosheets deposited by this method show unprecedented ultra-selective performance for separation of para- from ortho-xylene (separation factor >10 000).


Chemistry of Materials | 2018

Large-Grain, Oriented, and Thin Zeolite MFI Films from Directly Synthesized Nanosheet Coatings

Donghun Kim; Meera Shete; Michael Tsapatsis


Archive | 2018

DIRECT SYNTHESIS OF HIGH-ASPECT RATIO ZEOLITE NANOSHEETS

Michael Tsapatsis; Mi Young Jeon; Pyung Cheon Lee; Donghun Kim; Prashant Kumar; Andre Mkhoyan; Ilja Siepmann


Angewandte Chemie | 2018

Titelbild: para -Xylene Ultra-selective Zeolite MFI Membranes Fabricated from Nanosheet Monolayers at the Air-Water Interface (Angew. Chem. 2/2018)

Donghun Kim; Mi Young Jeon; Benjamin L. Stottrup; Michael Tsapatsis


Angewandte Chemie | 2018

Cover Picture: para-Xylene Ultra-selective Zeolite MFI Membranes Fabricated from Nanosheet Monolayers at the Air–Water Interface (Angew. Chem. Int. Ed. 2/2018)

Donghun Kim; Mi Young Jeon; Benjamin L. Stottrup; Michael Tsapatsis


Angewandte Chemie | 2018

Corrigendum: Nanoscale Control of Homoepitaxial Growth on a Two‐Dimensional Zeolite

Meera Shete; Manjesh Kumar; Donghun Kim; Neel Rangnekar; Dandan Xu; Berna Topuz; Kumar Varoon Agrawal; E. Karapetrova; Benjamin L. Stottrup; Shaeel A. Al-Thabaiti; Sulaiman N. Basahel; Katabathini Narasimharao; Jeffrey D. Rimer; Michael Tsapatsis


Angewandte Chemie | 2018

Berichtigung: Nanoscale Control of Homoepitaxial Growth on a Two-Dimensional Zeolite

Meera Shete; Manjesh Kumar; Donghun Kim; Neel Rangnekar; Dandan Xu; Berna Topuz; Kumar Varoon Agrawal; E. Karapetrova; Benjamin L. Stottrup; Shaeel A. Al-Thabaiti; Sulaiman N. Basahel; Katabathini Narasimharao; Jeffrey D. Rimer; Michael Tsapatsis


Angewandte Chemie | 2017

Cover Picture: Nanoscale Control of Homoepitaxial Growth on a Two-Dimensional Zeolite (Angew. Chem. Int. Ed. 2/2017)

Meera Shete; Manjesh Kumar; Donghun Kim; Neel Rangnekar; Dandan Xu; Berna Topuz; Kumar Varoon Agrawal; E. Karapetrova; Benjamin L. Stottrup; Shaeel A. Al-Thabaiti; Sulaiman N. Basahel; Katabathini Narasimharao; Jeffrey D. Rimer; Michael Tsapatsis

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Meera Shete

University of Minnesota

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Dandan Xu

University of Minnesota

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E. Karapetrova

Argonne National Laboratory

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