Publications by Heng-Yu Chi | EPFL Graph Search

Non-van-der-Waals Oriented Two-Dimensional UiO-66 Films by Rapid Aqueous Synthesis at Room Temperature

Wendy Lee Queen, Kumar Varoon Agrawal, Heng-Yu Chi, Qi Liu, Kuang-Jung Hsu, Kangning Zhao, Shuqing Song, Ranadip Goswami

The synthesis of MOFs in a two-dimensional (2D) film morphology is attractive for several applications including molecular and ionic separation. However, 2D MOFs have only been reported from structures that crystallize in lamellar morphology, where layers ...

2025

Modulation of Graphene Oxidation Using Substrate-Induced Electron-Hole Puddles for Advancing Molecular Separation

Kumar Varoon Agrawal, Shiqi Huang, Heng-Yu Chi, Kuang-Jung Hsu, Ranadip Goswami

Tuning the reactivity of graphene enables molecular-level engineering of the lattice, achieving desired chemical and structural properties through functionalization, doping, and etching. Atom-thin graphene film hosting Å-scale pores, with capability to dif ...

2025

Angstrom‐Scale Triangular Pore in Single‐Layer Hexagonal Boron Nitride Membrane for Molecular Sieving

Kumar Varoon Agrawal, Luis Francisco Villalobos Vazquez de la Parra, Heng-Yu Chi

Single‐layer crystalline films are ideal separation membrane materials because their atomic thickness could yield the highest possible molecular flux once nanopores are generated. However, the development of single‐layer membranes with well‐defined pore st ...

Wiley2025

Crystal, defect, and morphology engineering of porous two-dimensional materials for ionic separation

Heng-Yu Chi

Ordered two-dimensional (2D) materials hosting Å-scale pores are highly promising for enabling challenging separation, thanks to well-defined pore geometry resulting in tight confinement of ions when hosted inside the pore. In addition, the 2D nature of th ...

EPFL2024

Graphene membranes with pyridinic nitrogen at pore edges for high-performance CO2 capture

Andreas Züttel, Kumar Varoon Agrawal, Shiqi Huang, Luis Francisco Villalobos Vazquez de la Parra, Heng-Yu Chi, Shaoxian Li, Kuang-Jung Hsu, Marina Micari, Xuekui Duan, Liping Zhong, Shuqing Song

Membranes based on a porous two-dimensional selective layer offer the potential to achieve exceptional performance to improve energy efficiency and reduce the cost for carbon capture. So far, separation from two-dimensional pores has exploited differences ...

Nature Portfolio2024

Advancing Molecular Sieving via Å-Scale Pore Tuning in Bottom-Up Graphene Synthesis

Mounir Driss Mensi, Kumar Varoon Agrawal, Heng-Yu Chi, Kangning Zhao, Cédric Karel J Van Goethem

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 def ...

Amer Chemical Soc2024

Electrochemical-repaired porous graphene membranes for precise ion-ion separation

Kumar Varoon Agrawal, Heng-Yu Chi, Kuang-Jung Hsu, Kangning Zhao, Shuqing Song, Zongyao Zhou

The preparation of atom-thick porous lattice hosting & Aring;-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 incorpora ...

Nature Portfolio2024

High-performance H2/CO2 separation from 4-nm-thick oriented Zn2(benzimidazole)4 films

Kumar Varoon Agrawal, Heng-Yu Chi, Qi Liu, Shuqing Song, Zongyao Zhou, Ranadip Goswami

High-performance membrane-based H2/CO2 separation offers a promising way to reduce the energy costs of precombustion capture. Current membranes, often made from two-dimensional laminates like metal-organic frameworks, have limitations due to complex fabric ...

2024

Tuning Pore Size in Graphene in the Angstrom Regime for Highly Selective Ion-Ion Separation

Kumar Varoon Agrawal, Luis Francisco Villalobos Vazquez de la Parra, Heng-Yu Chi, Wan-Chi Lee, Shaoxian Li, Kuang-Jung Hsu, Kangning Zhao, Yuyang Zhang

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 ...

Amer Chemical Soc2024

Development of tuneable polyamine top layer for nanofiltration with high stability in bleach and at extreme pHs

Kumar Varoon Agrawal, Heng-Yu Chi, Cédric Karel J Van Goethem

State-of-the-art membranes for nanofiltration are thin film composite membranes, comprising of a thin top layer on top of a porous support. Many separation processes in organic chemistry involve extreme conditions, e.g. aggressive solvents, solvent-water m ...

Elsevier2023

Fabrication of ZIF-8 membranes by direct assembly of nanosheets from bottom-up synthesis growth solution

Kumar Varoon Agrawal, Heng-Yu Chi, Xuekui Duan

Metal-organic frameworks (MOFs) host intrinsically porous structure and rich structural and chemical features. Several MOFs with pore aperture comparable to the size of gas molecules have attracted interest to form the selective layer of membranes. Synthes ...

ELSEVIER2023

Towards ultrathin metal-organic frameworks membranes for high-performance separation

Kumar Varoon Agrawal, Heng-Yu Chi, Qi Liu, Shuqing Song, Ranadip Goswami

Research on metal-organic frameworks (MOFs) based membranes has gained a lot of attention in the last decade thanks to the unique and highly versatile chemistry of MOFs, which allows one to synthesize a variety of structural dimensions, topologies, pore si ...

Aip Publishing2023

Unit-cell-thick zeolitic imidazolate framework films for membrane application

Yu Han, Deepu Joseph Babu, Kumar Varoon Agrawal, Luis Francisco Villalobos Vazquez de la Parra, Heng-Yu Chi, Shaoxian Li, Qi Liu, Jian Hao, Shuqing Song

Zeolitic imidazolate frameworks (ZIFs) are a subset of metal-organic frameworks with more than 200 characterized crystalline and amorphous networks made of divalent transition metal centres (for example, Zn2+ and Co2+) linked by imidazolate linkers. ZIF th ...

NATURE PORTFOLIO2023

In Situ Nucleation-Decoupled and Site-Specific Incorporation of angstrom-Scale Pores in Graphene Via Epoxidation

Nicola Marzari, Luc Sébastien Bondaz, Kumar Varoon Agrawal, Shiqi Huang, Mohammad Tohidivahdat, Luis Francisco Villalobos Vazquez de la Parra, Heng-Yu Chi, Shaoxian Li, Kuang-Jung Hsu, Victor Carle Adrien Boureau

Generating pores in graphene by decoupled nucleation and expansion is desired to achieve a fine control over the porosity, and is desired to advance several applications. Herein, epoxidation is introduced, which is the formation of nanosized epoxy clusters ...

Wiley-V C H Verlag Gmbh2022

Unblocking Ion-occluded Pore Channels in Poly(triazine imide) Framework for Proton Conduction

Kumar Varoon Agrawal, Pascal Alexander Schouwink, Luis Francisco Villalobos Vazquez de la Parra, Heng-Yu Chi, Qi Liu, Kangning Zhao, Laura Piveteau

Poly(triazine imide) or PTI is an ordered graphitic carbon nitride hosting angstrom-scale pores attractive for selective molecular transport. AA'-stacked PTI layers are synthesized by ionothermal route during which ions occupy the framework and occlude the ...

Wiley-VCH Verlag GmbH2022

Multipulsed Millisecond Ozone Gasification for Predictable Tuning of Nucleation and Nucleation-Decoupled Nanopore Expansion in Graphene for Carbon Capture

Mounir Driss Mensi, Kumar Varoon Agrawal, Shiqi Huang, Guangwei He, Mostapha Dakhchoune, Luis Francisco Villalobos Vazquez de la Parra, Heng-Yu Chi, Wan-Chi Lee, Kuang-Jung Hsu

Predictable and tunable etching of angstrom-scale nanopores in single-layer graphene (SLG) can allow one to realize high-performance gas separation even from similar-sized molecules. We advance toward this goal by developing two etching regimes for SLG whe ...

2021

Synthesis of high-performance polycrystalline metal-organic framework membranes at room temperature in a few minutes

Deepu Joseph Babu, Kumar Varoon Agrawal, Heng-Yu Chi, Qi Liu, Jian Hao

The development of a rapid and reproducible crystallization route for the synthesis of polycrystalline metal-organic framework (MOF) films is attractive for the scalable production of nanoporous membranes on porous supports. Prior crystallization studies h ...

Royal Society of Chemistry2020