Recherche

Afficher tous les résultats pour

Accueil

Personne

Kumar Varoon Agrawal

À propos
Confidentialité
Mentions légales

Graph Chatbot

Publications associées (72)

Machine-learning accelerated identification of exfoliable two-dimensional materials

Giovanni Pizzi, Kumar Varoon Agrawal, Mohammad Tohidivahdat

Two-dimensional (2D) materials have been a central focus of recent research because they host a variety of properties, making them attractive both for fundamental science and for applications. It is thus crucial to be able to identify accurately and effici ...

IOP Publishing Ltd2022

Structure Evolution of Graphitic Surface upon Oxidation: Insights by Scanning Tunneling Microscopy

Mounir Driss Mensi, Nicola Marzari, Kumar Varoon Agrawal, Shiqi Huang, Mohammad Tohidivahdat, Shaoxian Li, Kuang-Jung Hsu

Oxidation of graphitic materials has been studied for more than a century to synthesize materials such as graphene oxide, nanoporous graphene, and to cut or unzip carbon nanotubes. However, the understanding of the early stages of oxidation is limited to t ...

AMER CHEMICAL SOC2022

Rapid Gas Transport from Block-Copolymer Templated Nanoporous Carbon Films

Kumar Varoon Agrawal, Mostapha Dakhchoune, Jing Zhao, Luis Francisco Villalobos Vazquez de la Parra, Kuang-Jung Hsu, Marina Micari, Xuekui Duan

Porous carbon films, attributed to their superior thermal and chemical robustness, are attractive for a number of applications. In the context of molecular separation, a major focus has been on films where the effective pore diameter is lower than 1 nm, e. ...

AMER CHEMICAL SOC2021

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

Method of preparation of porous polymeric support layer and uses thereof

Deepu Joseph Babu, Kumar Varoon Agrawal, Luis Francisco Villalobos Vazquez de la Parra

The invention relates to methods for the preparation of polymer supported graphene membrane by non-solvent induced phase separation and resulting products thereof, in particular useful for the preparation of gas separation membranes, in particular for He o ...

2021

Bottom-up synthesis of graphene films hosting atom-thick molecular-sieving apertures

Emad Oveisi, Mina Moradi, Kumar Varoon Agrawal, Shiqi Huang, Mostapha Dakhchoune, Luis Francisco Villalobos Vazquez de la Parra, Shaoxian Li, Kuang-Jung Hsu, Victor Carle Adrien Boureau, Kangning Zhao, Cédric Karel J Van Goethem

Incorporation of a high density of molecular-sieving nanopores in the graphene lattice by the bottom-up synthesis is highly attractive for high-performance membranes. Herein, we achieve this by a controlled synthesis of nanocrystalline graphene where incom ...

National Academy of Sciences2021

Mechanistic Study on Thermally Induced Lattice Stiffening of ZIF-8

Deepu Joseph Babu, Mehrdad Asgari, Wendy Lee Queen, Kumar Varoon Agrawal, Pascal Alexander Schouwink, Qi Liu, Jian Hao

The flexibility of the ZIF-8 aperture, which inhibits a molecular cutoff of 3.4 angstrom, can be reduced by rapid heat treatment to obtain CO2-selective membranes. However, the early stages of the structural, morphological, and chemical changes responsible ...

2021

Gas Transport across Carbon Nitride Nanopores: A Comparison of van der Waals Functionals against the Random-Phase Approximation

Nicola Marzari, Nicola Colonna, Kumar Varoon Agrawal, Davide Campi

C2N is an ordered two-dimensional carbon nitride with a high density (1.7 x 10 14 cm(-2)) of 3.1 angstrom-sized nanopores, making it promising for highflux gas sieving for energy-efficient He and H-2 purification. Herein, we discuss the accurate calculatio ...

AMER CHEMICAL SOC2021

Systematic design of millisecond gasification reactor for the incorporation of gas-sieving nanopores in single-layer graphene

Kumar Varoon Agrawal, Shiqi Huang, Luis Francisco Villalobos Vazquez de la Parra, Shaoxian Li, Kuang-Jung Hsu

Etching an ensemble of vacancy defects (nanopores) in single-layer graphene (SLG) to obtain a high density of nanopores with an effective size that enables high-performance gas sieving is challenging. This is because nanopore nucleation and expansion are u ...

2021

Millisecond lattice gasification for high-density CO2- and O2-sieving nanopores in single-layer graphene

Mounir Driss Mensi, Emad Oveisi, Deepu Joseph Babu, Kumar Varoon Agrawal, Shiqi Huang, Mostapha Dakhchoune, Luis Francisco Villalobos Vazquez de la Parra, Shaoxian Li, Marina Micari

Etching single-layer graphene to incorporate a high pore density with sub-angstrom precision in molecular differentiation is critical to realize the promising high-flux separation of similar-sized gas molecules, e.g., CO2 from N2. However, rapid etching ki ...

2021

Techno-economic assessment of postcombustion carbon capture using high-performance nanoporous single-layer graphene membranes

Kumar Varoon Agrawal, Mostapha Dakhchoune, Marina Micari

High-performance membranes have emerged as an energy-efficient alternative to absorption-based postcombustion carbon capture. So far, the techno-economic analyses have been centered around the polymeric membranes. Recently, nanoporous single-layer graphene ...

2021

Crystalline poly(triazine imide) membranes and uses thereof

Kumar Varoon Agrawal, Luis Francisco Villalobos Vazquez de la Parra

The invention relates to methods for the preparation of highly crystalline poly(triazine imide) in the form of platelets, atom-thick layers or membranes thereof and resulting products thereof, in particular useful for the preparation of gas separation memb ...

2021

Centimeter-scale gas-sieving nanoporous single-layer graphene membrane

Luc Sébastien Bondaz, Kumar Varoon Agrawal, Shiqi Huang, Guangwei He, Mostapha Dakhchoune, Wan-Chi Lee

High-permeance, molecular-sieving, nanoporous single-layer graphene (NSLG) membranes are highly promising for gas separation. However, the formation of cracks during the transfer of NSLG to a low-cost porous support is difficult to avoid. These cracks are ...

2020

Hybrid membranes for energy-efficient carbon capture

Kumar Varoon Agrawal, Guangwei He

Gas separation membrane comprising a porous support onto which is deposited a nanoporous single-layer graphene film with a CO2-philic polymer film having a thickness of 5-100 nm coated on top of graphene nanopores, acting as a CO2-selective film, wherein t ...

2020

Polybenzimidazole copolymer derived lacey carbon film for graphene transfer and contamination removal strategies for imaging graphene nanopores

Kumar Varoon Agrawal, Shiqi Huang, Guangwei He, Mostapha Dakhchoune, Luis Francisco Villalobos Vazquez de la Parra, Wan-Chi Lee

The study of the nanometer-scale vacancy defects (nanopores) in graphene by transmission electron microscopy (TEM) is severely hindered by the presence of polymeric residues originating from the graphene-transfer-step to the TEM grid. The state-of-the-art ...

2020

Hydrogen-sieving single-layer graphene membranes obtained by crystallographic and morphological optimization of catalytic copper foil

Kumar Varoon Agrawal, Shiqi Huang, Shaoxian Li

Gas separation membranes based on single-layer-graphene are highly attractive because the size of graphene nanopores can be tuned to separate gases by the size-sieving mechanism. A prerequisite for this, the synthesis of high-quality polycrystalline single ...

2020

Metal Soap Membranes for Gas Separation

Deepu Joseph Babu, Kumar Varoon Agrawal, Davide Campi, Qi Liu, Jian Hao

Metal soaps or metal alkanoates are metal-organic complexes held together with metal cations and the functional groups of hydrocarbon chains. They can be synthesized at a high yield by simply mixing the metal and organic sources, forming crystalline framew ...

2020

Synergistic CO2-Sieving from Polymer with Intrinsic Microporosity Masking Nanoporous Single-Layer Graphene

Mounir Driss Mensi, Kumar Varoon Agrawal, Shiqi Huang, Guangwei He, Jing Zhao, Luis Francisco Villalobos Vazquez de la Parra, Wan-Chi Lee

High-flux nanoporous single-layer graphene membranes are highly promising for energy-efficient gas separation. Herein, in the context of carbon capture, a remarkable enhancement in the CO(2)selectivity is demonstrated by uniquely masking nanoporous single- ...

WILEY-V C H VERLAG GMBH2020

Efficient Kr/Xe separation from triangular g-C(3)N(4)nanopores, a simulation study

Nicola Marzari, Nicola Colonna, Kumar Varoon Agrawal, Davide Campi, Luis Francisco Villalobos Vazquez de la Parra

Poly(triazine imide) or PTI is a promising material for molecular sieving membranes, thanks to its atom-thick ordered lattice with an extremely high density (1.6 x 10(14)pores per cm(2)) of triangular-shaped nanopores of similar to 0.34 nm diameter. Here, ...

Royal Society of Chemistry2020

Large-scale synthesis of crystalline g-C3N4 nanosheets and high-temperature H-2 sieving from assembled films

Mounir Driss Mensi, Emad Oveisi, Nicola Marzari, Kumar Varoon Agrawal, Davide Campi, Luis Francisco Villalobos Vazquez de la Parra, Zahra Nadizadeh

Poly(triazine imide) (PTI), a crystalline g-C3N4, hosting two-dimensional nanoporous structure with an electron density gap of 0.34 nm, is highly promising for high-temperature hydrogen sieving because of its high chemical and thermal robustness. Currently ...

AMER ASSOC ADVANCEMENT SCIENCE2020

Page 3 sur 4