1
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Guo L, Wu N, Zhang S, Zeng H, Yang J, Han X, Duan H, Liu Y, Wang L. Emerging Advances around Nanofluidic Transport and Mass Separation under Confinement in Atomically Thin Nanoporous Graphene. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2404087. [PMID: 39031097 DOI: 10.1002/smll.202404087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2024] [Revised: 07/07/2024] [Indexed: 07/22/2024]
Abstract
Membrane separation stands as an environmentally friendly, high permeance and selectivity, low energy demand process that deserves scientific investigation and industrialization. To address intensive demand, seeking appropriate membrane materials to surpass trade-off between permeability and selectivity and improve stability is on the schedule. 2D materials offer transformational opportunities and a revolutionary platform for researching membrane separation process. Especially, the atomically thin graphene with controllable porosity and structure, as well as unique properties, is widely considered as a candidate for membrane materials aiming to provide extreme stability, exponentially large selectivity combined with high permeability. Currently, it has shown promising opportunities to develop separation membranes to tackle bottlenecks of traditional membranes, and it has been of great interest for tremendously versatile applications such as separation, energy harvesting, and sensing. In this review, starting from transport mechanisms of separation, the material selection bank is narrowed down to nanoporous graphene. The study presents an enlightening overview of very recent developments in the preparation of atomically thin nanoporous graphene and correlates surface properties of such 2D nanoporous materials to their performance in critical separation applications. Finally, challenges related to modulation and manufacturing as well as potential avenues for performance improvements are also pointed out.
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Affiliation(s)
- Liping Guo
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, School of Integrated Circuits, Peking University, Beijing, 100871, China
- Beijing Advanced Innovation Center for Integrated Circuits, Beijing, 100871, China
| | - Ningran Wu
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, School of Integrated Circuits, Peking University, Beijing, 100871, China
- Beijing Advanced Innovation Center for Integrated Circuits, Beijing, 100871, China
- Academy for Advanced Interdisciplinary Studies and Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Peking University, Beijing, 100871, China
- Beijing Graphene Institute, Beijing, 100095, China
| | - Shengping Zhang
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, School of Integrated Circuits, Peking University, Beijing, 100871, China
- Beijing Advanced Innovation Center for Integrated Circuits, Beijing, 100871, China
- Academy for Advanced Interdisciplinary Studies and Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Peking University, Beijing, 100871, China
- Beijing Graphene Institute, Beijing, 100095, China
| | - Haiou Zeng
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, School of Integrated Circuits, Peking University, Beijing, 100871, China
- Beijing Advanced Innovation Center for Integrated Circuits, Beijing, 100871, China
| | - Jing Yang
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, School of Integrated Circuits, Peking University, Beijing, 100871, China
- Beijing Advanced Innovation Center for Integrated Circuits, Beijing, 100871, China
| | - Xiao Han
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, School of Integrated Circuits, Peking University, Beijing, 100871, China
- Beijing Advanced Innovation Center for Integrated Circuits, Beijing, 100871, China
- Academy for Advanced Interdisciplinary Studies and Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Peking University, Beijing, 100871, China
- Beijing Graphene Institute, Beijing, 100095, China
| | - Hongwei Duan
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, School of Integrated Circuits, Peking University, Beijing, 100871, China
- Beijing Advanced Innovation Center for Integrated Circuits, Beijing, 100871, China
- Academy for Advanced Interdisciplinary Studies and Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Peking University, Beijing, 100871, China
| | - Yuancheng Liu
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, School of Integrated Circuits, Peking University, Beijing, 100871, China
- Beijing Advanced Innovation Center for Integrated Circuits, Beijing, 100871, China
| | - Luda Wang
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, School of Integrated Circuits, Peking University, Beijing, 100871, China
- Beijing Advanced Innovation Center for Integrated Circuits, Beijing, 100871, China
- Academy for Advanced Interdisciplinary Studies and Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Peking University, Beijing, 100871, China
- Beijing Graphene Institute, Beijing, 100095, China
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2
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Zhou Z, Zhao K, Chi HY, Shen Y, Song S, Hsu KJ, Chevalier M, Shi W, Agrawal KV. Electrochemical-repaired porous graphene membranes for precise ion-ion separation. Nat Commun 2024; 15:4006. [PMID: 38740849 DOI: 10.1038/s41467-024-48419-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Accepted: 04/26/2024] [Indexed: 05/16/2024] Open
Abstract
The preparation of atom-thick porous lattice hosting Å-scale pores is attractive to achieve a large ion-ion selectivity in combination with a large ion flux. Graphene film is an ideal selective layer for this if high-precision pores can be incorporated, however, it is challenging to avoid larger non-selective pores at the tail-end of the pore size distribution which reduces ion-ion selectivity. Herein, we develop a strategy to overcome this challenge using an electrochemical repair strategy that successfully masks larger pores in large-area graphene. 10-nm-thick electropolymerized conjugated microporous polymer (CMP) layer is successfully deposited on graphene, thanks to a strong π-π interaction in these two materials. While the CMP layer itself is not selective, it effectively masks graphene pores, leading to a large Li+/Mg2+ selectivity from zero-dimensional pores reaching 300 with a high Li+ ion permeation rate surpassing the performance of reported materials for ion-ion separation. Overall, this scalable repair strategy enables the fabrication of monolayer graphene membranes with customizable pore sizes, limiting the contribution of nonselective pores, and offering graphene membranes a versatile platform for a broad spectrum of challenging separations.
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Affiliation(s)
- Zongyao Zhou
- Laboratory of Advanced Separations (LAS), École Polytechnique Fédérale de Lausanne (EPFL), Sion, CH-1950, Switzerland
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, 150090, P. R. China
| | - Kangning Zhao
- Laboratory of Advanced Separations (LAS), École Polytechnique Fédérale de Lausanne (EPFL), Sion, CH-1950, Switzerland
| | - Heng-Yu Chi
- Laboratory of Advanced Separations (LAS), École Polytechnique Fédérale de Lausanne (EPFL), Sion, CH-1950, Switzerland
| | - Yueqing Shen
- Laboratory of Advanced Separations (LAS), École Polytechnique Fédérale de Lausanne (EPFL), Sion, CH-1950, Switzerland
| | - Shuqing Song
- Laboratory of Advanced Separations (LAS), École Polytechnique Fédérale de Lausanne (EPFL), Sion, CH-1950, Switzerland
| | - Kuang-Jung Hsu
- Laboratory of Advanced Separations (LAS), École Polytechnique Fédérale de Lausanne (EPFL), Sion, CH-1950, Switzerland
| | - Mojtaba Chevalier
- Laboratory of Advanced Separations (LAS), École Polytechnique Fédérale de Lausanne (EPFL), Sion, CH-1950, Switzerland
| | - Wenxiong Shi
- Institute for New Energy Materials and Low Carbon Technologies, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin, 300387, P. R. China
| | - Kumar Varoon Agrawal
- Laboratory of Advanced Separations (LAS), École Polytechnique Fédérale de Lausanne (EPFL), Sion, CH-1950, Switzerland.
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3
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Goethem CV, Shen Y, Chi HY, Mensi M, Zhao K, Nijmeijer A, Just PE, Agrawal KV. Advancing Molecular Sieving via Å-Scale Pore Tuning in Bottom-Up Graphene Synthesis. ACS NANO 2024. [PMID: 38324377 PMCID: PMC10883125 DOI: 10.1021/acsnano.3c11885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2024]
Abstract
Porous graphene films are attractive as a gas separation membrane given that the selective layer can be just one atom thick, allowing high-flux separation. A favorable aspect of porous graphene is that the pore size, essentially gaps created by lattice defects, can be tuned. While this has been demonstrated for postsynthetic, top-down pore etching in graphene, it does not exist in the more scalable, bottom-up synthesis of porous graphene. Inspired by the mechanism of precipitation-based synthesis of porous graphene over catalytic nickel foil, we herein conceive an extremely simple way to tune the pore size. This is implemented by increasing the cooling rate by over 100-fold from -1 °C min-1 to over -5 °C s-1. Rapid cooling restricts carbon diffusion, resulting in a higher availability of dissolved carbon for precipitation, as evidenced by quantitative carbon-diffusion simulation, measurement of carbon concentration as a function of nickel depth, and imaging of the graphene nanostructure. The resulting enhanced grain (inter)growth reduces the effective pore size which leads to an increase of the H2/CH4 separation factor from 6.2 up to 53.3.
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Affiliation(s)
- Cédric Van Goethem
- Laboratory for Advanced Separations (LAS), Institute of Chemical Sciences and Engineering (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Rue de l'industrie 17, 1950 Sion, Switzerland
| | - Yueqing Shen
- Laboratory for Advanced Separations (LAS), Institute of Chemical Sciences and Engineering (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Rue de l'industrie 17, 1950 Sion, Switzerland
| | - Heng-Yu Chi
- Laboratory for Advanced Separations (LAS), Institute of Chemical Sciences and Engineering (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Rue de l'industrie 17, 1950 Sion, Switzerland
| | - Mounir Mensi
- X-ray Diffraction and Surface Analytics Platform (XRD-SAP), Institute of Chemical Sciences and Engineering (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL-Valais Wallis), Rue de l'industrie 17, 1950 Sion, Switzerland
| | - Kangning Zhao
- Laboratory for Advanced Separations (LAS), Institute of Chemical Sciences and Engineering (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Rue de l'industrie 17, 1950 Sion, Switzerland
| | - Arian Nijmeijer
- Shell Global Solutions International B.V., P.O. Box 38000, 1030 BN Amsterdam, The Netherlands
- Inorganic Membranes, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Paul-Emmanuel Just
- Shell Global Solutions International B.V., P.O. Box 38000, 1030 BN Amsterdam, The Netherlands
| | - Kumar Varoon Agrawal
- Laboratory for Advanced Separations (LAS), Institute of Chemical Sciences and Engineering (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Rue de l'industrie 17, 1950 Sion, Switzerland
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4
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Zhao K, Lee WC, Rezaei M, Chi HY, Li S, Villalobos LF, Hsu KJ, Zhang Y, Wang FC, Agrawal KV. Tuning Pore Size in Graphene in the Angstrom Regime for Highly Selective Ion-Ion Separation. ACS NANO 2024. [PMID: 38320296 PMCID: PMC10883049 DOI: 10.1021/acsnano.3c11068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2024]
Abstract
Zero-dimensional pores spanning only a few angstroms in size in two-dimensional materials such as graphene are some of the most promising systems for designing ion-ion selective membranes. However, the key challenge in the field is that so far a crack-free macroscopic graphene membrane for ion-ion separation has not been realized. Further, methods to tune the pores in the Å-regime to achieve a large ion-ion selectivity from the graphene pore have not been realized. Herein, we report an Å-scale pore size tuning tool for single layer graphene, which incorporates a high density of ion-ion selective pores between 3.5 and 8.5 Å while minimizing the nonselective pores above 10 Å. These pores impose a strong confinement for ions, which results in extremely high selectivity from centimeter-scale porous graphene between monovalent and bivalent ions and near complete blockage of ions with the hydration diameter, DH, greater than 9.0 Å. The ion diffusion study reveals the presence of an energy barrier corresponding to partial dehydration of ions with the barrier increasing with DH. We observe a reversal of K+/Li+ selectivity at elevated temperature and attribute this to the relative size of the dehydrated ions. These results underscore the promise of porous two-dimensional materials for solute-solute separation when Å-scale pores can be incorporated in a precise manner.
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Affiliation(s)
- Kangning Zhao
- Laboratory of Advanced Separations (LAS), École Polytechnique Fédérale de Lausanne (EPFL), Sion, CH-1950 Switzerland
| | - Wan-Chi Lee
- Laboratory of Advanced Separations (LAS), École Polytechnique Fédérale de Lausanne (EPFL), Sion, CH-1950 Switzerland
| | - Mojtaba Rezaei
- Laboratory of Advanced Separations (LAS), École Polytechnique Fédérale de Lausanne (EPFL), Sion, CH-1950 Switzerland
| | - Heng-Yu Chi
- Laboratory of Advanced Separations (LAS), École Polytechnique Fédérale de Lausanne (EPFL), Sion, CH-1950 Switzerland
| | - Shaoxian Li
- Laboratory of Advanced Separations (LAS), École Polytechnique Fédérale de Lausanne (EPFL), Sion, CH-1950 Switzerland
| | - Luis Francisco Villalobos
- Laboratory of Advanced Separations (LAS), École Polytechnique Fédérale de Lausanne (EPFL), Sion, CH-1950 Switzerland
| | - Kuang-Jung Hsu
- Laboratory of Advanced Separations (LAS), École Polytechnique Fédérale de Lausanne (EPFL), Sion, CH-1950 Switzerland
| | - Yuyang Zhang
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei 230027, China
| | - Feng-Chao Wang
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei 230027, China
| | - Kumar Varoon Agrawal
- Laboratory of Advanced Separations (LAS), École Polytechnique Fédérale de Lausanne (EPFL), Sion, CH-1950 Switzerland
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5
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Vahdat M, Li S, Huang S, Bondaz L, Bonnet N, Hsu KJ, Marzari N, Agrawal KV. Mechanistic Insights on Functionalization of Graphene with Ozone. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2023; 127:22015-22022. [PMID: 38024196 PMCID: PMC10658624 DOI: 10.1021/acs.jpcc.3c03994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 10/21/2023] [Accepted: 10/24/2023] [Indexed: 12/01/2023]
Abstract
The exposure of graphene to O3 results in functionalization of its lattice with epoxy, even at room temperature. This reaction is of fundamental interest for precise lattice patterning, however, is not well understood. Herein, using van der Waals density functional theory (vdW-DFT) incorporating spin-polarized calculations, we find that O3 strongly physisorbs on graphene with a binding energy of -0.46 eV. It configures in a tilted position with the two terminal O atoms centered above the neighboring graphene honeycombs. A dissociative chemisorption follows by surpassing an energy barrier of 0.75 eV and grafting an epoxy group on graphene reducing the energy of the system by 0.14 eV from the physisorbed state. Subsequent O3 chemisorption is preferred on the same honeycomb, yielding two epoxy groups separated by a single C-C bridge. We show that capturing the onset of spin in oxygen during chemisorption is crucial. We verify this finding with experiments where an exponential increase in the density of epoxy groups as a function of reaction temperature yields an energy barrier of 0.66 eV, in agreement with the DFT prediction. These insights will help efforts to obtain precise patterning of the graphene lattice.
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Affiliation(s)
- Mohammad
Tohidi Vahdat
- Laboratory
of Advanced Separations (LAS), École
Polytechnique Fédérale de Lausanne (EPFL), Sion CH-1950, Switzerland
- Theory
and Simulation of Materials (THEOS) and National Centre for Computational
Design and Discovery of Novel Materials (MARVEL), EPFL, Lausanne CH-1015, Switzerland
| | - Shaoxian Li
- Laboratory
of Advanced Separations (LAS), École
Polytechnique Fédérale de Lausanne (EPFL), Sion CH-1950, Switzerland
| | - Shiqi Huang
- Laboratory
of Advanced Separations (LAS), École
Polytechnique Fédérale de Lausanne (EPFL), Sion CH-1950, Switzerland
| | - Luc Bondaz
- Laboratory
of Advanced Separations (LAS), École
Polytechnique Fédérale de Lausanne (EPFL), Sion CH-1950, Switzerland
| | - Nicéphore Bonnet
- Theory
and Simulation of Materials (THEOS) and National Centre for Computational
Design and Discovery of Novel Materials (MARVEL), EPFL, Lausanne CH-1015, Switzerland
| | - Kuang-Jung Hsu
- Laboratory
of Advanced Separations (LAS), École
Polytechnique Fédérale de Lausanne (EPFL), Sion CH-1950, Switzerland
| | - Nicola Marzari
- Theory
and Simulation of Materials (THEOS) and National Centre for Computational
Design and Discovery of Novel Materials (MARVEL), EPFL, Lausanne CH-1015, Switzerland
| | - Kumar Varoon Agrawal
- Laboratory
of Advanced Separations (LAS), École
Polytechnique Fédérale de Lausanne (EPFL), Sion CH-1950, Switzerland
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6
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Wang J, Cheng C, Zheng X, Idrobo JC, Lu AY, Park JH, Shin BG, Jung SJ, Zhang T, Wang H, Gao G, Shin B, Jin X, Ju L, Han Y, Li LJ, Karnik R, Kong J. Cascaded compression of size distribution of nanopores in monolayer graphene. Nature 2023; 623:956-963. [PMID: 38030784 DOI: 10.1038/s41586-023-06689-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 09/28/2023] [Indexed: 12/01/2023]
Abstract
Monolayer graphene with nanometre-scale pores, atomically thin thickness and remarkable mechanical properties provides wide-ranging opportunities for applications in ion and molecular separations1, energy storage2 and electronics3. Because the performance of these applications relies heavily on the size of the nanopores, it is desirable to design and engineer with precision a suitable nanopore size with narrow size distributions. However, conventional top-down processes often yield log-normal distributions with long tails, particularly at the sub-nanometre scale4. Moreover, the size distribution and density of the nanopores are often intrinsically intercorrelated, leading to a trade-off between the two that substantially limits their applications5-9. Here we report a cascaded compression approach to narrowing the size distribution of nanopores with left skewness and ultrasmall tail deviation, while keeping the density of nanopores increasing at each compression cycle. The formation of nanopores is split into many small steps, in each of which the size distribution of all the existing nanopores is compressed by a combination of shrinkage and expansion and, at the same time as expansion, a new batch of nanopores is created, leading to increased nanopore density by each cycle. As a result, high-density nanopores in monolayer graphene with a left-skewed, short-tail size distribution are obtained that show ultrafast and ångström-size-tunable selective transport of ions and molecules, breaking the limitation of the conventional log-normal size distribution9,10. This method allows for independent control of several metrics of the generated nanopores, including the density, mean diameter, standard deviation and skewness of the size distribution, which will lead to the next leap in nanotechnology.
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Affiliation(s)
- Jiangtao Wang
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Chi Cheng
- Department of Chemical Engineering, University of Melbourne, Parkville, Victoria, Australia.
- School of Chemical Engineering, University of New South Wales (UNSW), Kensington, New South Wales, Australia.
| | - Xudong Zheng
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Juan Carlos Idrobo
- Materials Science and Engineering Department, University of Washington, Seattle, WA, USA
| | - Ang-Yu Lu
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ji-Hoon Park
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Bong Gyu Shin
- Max Planck Institute for Solid State Research, Stuttgart, Germany
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University (SKKU), Suwon, Republic of Korea
| | - Soon Jung Jung
- Max Planck Institute for Solid State Research, Stuttgart, Germany
| | - Tianyi Zhang
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Haozhe Wang
- Department of Electrical and Computer Engineering, Duke University, Durham, NC, USA
| | - Guanhui Gao
- Materials Science and NanoEngineering Department, Rice University, Houston, TX, USA
| | - Bongki Shin
- Materials Science and NanoEngineering Department, Rice University, Houston, TX, USA
| | - Xiang Jin
- Department of Physics, Tsinghua University, Beijing, China
| | - Long Ju
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Yimo Han
- Materials Science and NanoEngineering Department, Rice University, Houston, TX, USA
| | - Lain-Jong Li
- Department of Mechanical Engineering, University of Hong Kong, Hong Kong SAR, China
| | - Rohit Karnik
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jing Kong
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA.
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7
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Bondaz L, Ronghe A, Li S, Čerņevičs K, Hao J, Yazyev OV, Ayappa KG, Agrawal KV. Selective Photonic Gasification of Strained Oxygen Clusters on Graphene for Tuning Pore Size in the Å Regime. JACS AU 2023; 3:2844-2854. [PMID: 37885574 PMCID: PMC10598578 DOI: 10.1021/jacsau.3c00395] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 09/07/2023] [Accepted: 09/14/2023] [Indexed: 10/28/2023]
Abstract
Controlling the size of single-digit pores, such as those in graphene, with an Å resolution has been challenging due to the limited understanding of pore evolution at the atomic scale. The controlled oxidation of graphene has led to Å-scale pores; however, obtaining a fine control over pore evolution from the pore precursor (i.e., the oxygen cluster) is very attractive. Herein, we introduce a novel "control knob" for gasifying clusters to form pores. We show that the cluster evolves into a core/shell structure composed of an epoxy group surrounding an ether core in a bid to reduce the lattice strain at the cluster core. We then selectively gasified the strained core by exposing it to 3.2 eV of light at room temperature. This allowed for pore formation with improved control compared to thermal gasification. This is because, for the latter, cluster-cluster coalescence via thermally promoted epoxy diffusion cannot be ruled out. Using the oxidation temperature as a control knob, we were able to systematically increase the pore density while maintaining a narrow size distribution. This allowed us to increase H2 permeance as well as H2 selectivity. We further show that these pores could differentiate CH4 from N2, which is considered to be a challenging separation. Dedicated molecular dynamics simulations and potential of mean force calculations revealed that the free energy barrier for CH4 translocation through the pores was lower than that for N2. Overall, this study will inspire research on the controlled manipulation of clusters for improved precision in incorporating Å-scale pores in graphene.
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Affiliation(s)
- Luc Bondaz
- Laboratory
of Advanced Separations, Institute of Chemical
Sciences & Engineering, École Polytechnique Fédérale
de Lausanne (EPFL), CH-1950 Sion, Switzerland
| | - Anshaj Ronghe
- Department
of Chemical Engineering, Indian Institute
of Science, Bangalore 560012, India
| | - Shaoxian Li
- Laboratory
of Advanced Separations, Institute of Chemical
Sciences & Engineering, École Polytechnique Fédérale
de Lausanne (EPFL), CH-1950 Sion, Switzerland
| | | | - Jian Hao
- Laboratory
of Advanced Separations, Institute of Chemical
Sciences & Engineering, École Polytechnique Fédérale
de Lausanne (EPFL), CH-1950 Sion, Switzerland
| | - Oleg V. Yazyev
- Institute
of Physics, EPFL, Lausanne CH-1015, Switzerland
| | - K. Ganapathy Ayappa
- Department
of Chemical Engineering, Indian Institute
of Science, Bangalore 560012, India
| | - Kumar Varoon Agrawal
- Laboratory
of Advanced Separations, Institute of Chemical
Sciences & Engineering, École Polytechnique Fédérale
de Lausanne (EPFL), CH-1950 Sion, Switzerland
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