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Dive into the research topics where Ming Huang is active.

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Featured researches published by Ming Huang.


Scientific Reports | 2015

Self-Assembly of Mesoporous Nanotubes Assembled from Interwoven Ultrathin Birnessite-type MnO2 Nanosheets for Asymmetric Supercapacitors

Ming Huang; Yuxin Zhang; Fei Li; Lili Zhang; Rodney S. Ruoff; Zhiyu Wen; Qing Liu

Porous nanotubes comprised of MnO2 nanosheets were fabricated with a one-pot hydrothermal method using polycarbonate membrane as the template. The diameter and thickness of nanotubes can be controlled by choice of the membrane pore size and the chemistry. The porous MnO2 nanotubes were used as a supercapacitor electrode. The specific capacitance in a three-electrode system was 365u2005F g−1 at a current density of 0.25u2005A g−1 with capacitance retention of 90.4% after 3000 cycles. An asymmetric supercapacitor with porous MnO2 nanotubes as the positive electrode and activated graphene as the negative electrode yielded an energy density of 22.5u2005Wh kg−1 and a maximum power density of 146.2u2005kW kg−1; these values exceeded those reported for other MnO2 nanostructures. The supercapacitor performance was correlated with the hierarchical structure of the porous MnO2 nanotubes.


Scientific Reports | 2015

Merging of Kirkendall Growth and Ostwald Ripening: CuO@MnO2 Core-shell Architectures for Asymmetric Supercapacitors

Ming Huang; Yuxin Zhang; Fei Li; Zhongchang Wang; Alamusi; Ning Hu; Zhiyu Wen; Qing Liu

Fabricating hierarchical core-shell nanostructures is currently the subject of intensive research in the electrochemical field owing to the hopes it raises for making efficient electrodes for high-performance supercapacitors. Here, we develop a simple and cost-effective approach to prepare CuO@MnO2 core-shell nanostructures without any surfactants and report their applications as electrodes for supercapacitors. An asymmetric supercapacitor with CuO@MnO2 core-shell nanostructure as the positive electrode and activated microwave exfoliated graphite oxide (MEGO) as the negative electrode yields an energy density of 22.1u2005Wh kg−1 and a maximum power density of 85.6u2005kW kg−1; the device shows a long-term cycling stability which retains 101.5% of its initial capacitance even after 10000 cycles. Such a facile strategy to fabricate the hierarchical CuO@MnO2 core-shell nanostructure with significantly improved functionalities opens up a novel avenue to design electrode materials on demand for high-performance supercapacitor applications.


ACS Nano | 2016

Support-Free Transfer of Ultrasmooth Graphene Films Facilitated by Self-Assembled Monolayers for Electronic Devices and Patterns

Bin Wang; Ming Huang; Li Tao; Sun Hwa Lee; A-Rang Jang; Bao-Wen Li; Hyeon Suk Shin; Deji Akinwande; Rodney S. Ruoff

We explored a support-free method for transferring large area graphene films grown by chemical vapor deposition to various fluoric self-assembled monolayer (F-SAM) modified substrates including SiO2/Si wafers, polyethylene terephthalate films, and glass. This method yields clean, ultrasmooth, and high-quality graphene films for promising applications such as transparent, conductive, and flexible films due to the absence of residues and limited structural defects such as cracks. The F-SAM introduced in the transfer process can also lead to graphene transistors with enhanced field-effect mobility (up to 10,663 cm(2)/Vs) and resistance modulation (up to 12×) on a standard silicon dioxide dielectric. Clean graphene patterns can be realized by transfer of graphene onto only the F-SAM modified surfaces.


ACS Nano | 2017

Controlling the Thickness of Thermally Expanded Films of Graphene Oxide

Xianjue Chen; Wei Li; Da Luo; Ming Huang; Xiaozhong Wu; Yuan Huang; Sun Hwa Lee; Xiong Chen; Rodney S. Ruoff

Paper-like film material made from stacked and overlapping graphene oxide sheets can be exfoliated (expanded) through rapid heating, and this has until now been done with no control of the final geometry of the expanded graphene oxide material, i.e., the expansion has been physically unconstrained. (As a consequence of the heating and exfoliation, the graphene oxide is reduced, i.e., the graphene oxide platelets are deoxygenated to a degree.) We have used a confined space to constrain the expanding films to a controllable and uniform thickness. By changing the gap above the film, the final thickness of expanded films prepared from, e.g., a 10 μm-thick graphene oxide film, could be controlled to values such as 20, 30, 50, or 100 μm. When the expansion of the films was unconstrained, the final film was broken into pieces or had many cracks. In contrast, when the expansion was constrained, it never cracked or broke. Hot pressing the expanded reduced graphene oxide films at 1000 °C yielded a highly compact structure and promoted graphitization. Such thickness-controlled expansion of graphene oxide films up to tens or hundreds of times the original film thickness was used to emboss patterns on the films to produce areas with different thicknesses that remain connected in plane. In another set of experiments, we treated the original graphene oxide film with NaOH before its controlled expansion resulted in a different structure featuring uniformly distributed pores and interconnected layers as well as simultaneous activation of the carbon.


Nano Letters | 2017

Controlled Folding of Single Crystal Graphene

Bin Wang; Ming Huang; Na Yeon Kim; Benjamin V. Cunning; Yuan Huang; Deshun Qu; Xianjue Chen; Sunghwan Jin; Mandakini Biswal; Xu Zhang; Sun Hwa Lee; Hyunseob Lim; Won Jong Yoo; Zonghoon Lee; Rodney S. Ruoff

Folded graphene in which two layers are stacked with a twist angle between them has been predicted to exhibit unique electronic, thermal, and magnetic properties. We report the folding of a single crystal monolayer graphene film grown on a Cu(111) substrate by using a tailored substrate having a hydrophobic region and a hydrophilic region. Controlled film delamination from the hydrophilic region was used to prepare macroscopic folded graphene with good uniformity on the millimeter scale. This process was used to create many folded sheets each with a defined twist angle between the two sheets. By identifying the original lattice orientation of the monolayer graphene on Cu foil, or establishing the relation between the fold angle and twist angle, this folding technique allows for the preparation of twisted bilayer graphene films with defined stacking orientations and may also be extended to create folded structures of other two-dimensional nanomaterials.


Advanced Materials | 2017

Carrier‐Type Modulation and Mobility Improvement of Thin MoTe2

Deshun Qu; Xiaochi Liu; Ming Huang; Changmin Lee; Faisal Ahmed; Hyoungsub Kim; Rodney S. Ruoff; James Hone; Won Jong Yoo

A systematic modulation of the carrier type in molybdenum ditelluride (MoTe2 ) field-effect transistors (FETs) is described, through rapid thermal annealing (RTA) under a controlled O2 environment (p-type modulation) and benzyl viologen (BV) doping (n-type modulation). Al2 O3 capping is then introduced to improve the carrier mobilities and device stability. MoTe2 is found to be ultrasensitive to O2 at elevated temperatures (250 °C). Charge carriers of MoTe2 flakes annealed via RTA at various vacuum levels are tuned between predominantly pristine n-type ambipolar, symmetric ambipolar, unipolar p-type, and degenerate-like p-type. Changes in the MoTe2 -transistor performance are confirmed to originate from the physical and chemical absorption and dissociation of O2 , especially at tellurium vacancy sites. The electron branch is modulated by varying the BV dopant concentrations and annealing conditions. Unipolar n-type MoTe2 FETs with a high on-off ratio exceeding 106 are achieved under optimized doping conditions. By introducing Al2 O3 capping, carrier field effect mobilities (41 for holes and 80 cm2 V-1 s-1 for electrons) and device stability are improved due to the reduced trap densities and isolation from ambient air. Lateral MoTe2 p-n diodes with an ideality factor of 1.2 are fabricated using the p- and n-type doping technique to test the superb potential of the doping method in functional electronic device applications.


ACS Applied Materials & Interfaces | 2017

Porous Two-Dimensional Monolayer Metal–Organic Framework Material and Its Use for the Size-Selective Separation of Nanoparticles

Yi Jiang; Gyeong Hee Ryu; Se Hun Joo; Xiong Chen; Sun Hwa Lee; Xianjue Chen; Ming Huang; Xiaozhong Wu; Da Luo; Yuan Huang; Jeong Hyeon Lee; Bin Wang; Xu Zhang; Sang Kyu Kwak; Zonghoon Lee; Rodney S. Ruoff

Rational bottom-up construction of two-dimensional (2D) covalent or noncovalent organic materials with precise structural control at the atomic or molecular level remains a challenge. The design and synthesis of metal-organic frameworks (MOFs) based on new building blocks is of great significance in achieving new types of 2D monolayer MOF films. Here, we demonstrate that a complexation between copper(II) ions and tri(β-diketone) ligands yields a novel 2D MOF structure, either in the form of a powder or as a monolayer film. It has been characterized by Fourier transform infrared, Raman, ultraviolet-visible, X-ray photoelectron, and electron paramagnetic resonance spectroscopies. Selected area electron diffraction and powder X-ray diffraction results show that the MOF is crystalline and has a hexagonal structure. A MOF-based membrane has been prepared by vacuum filtration of an aqueous dispersion of the MOF powder onto a porous Anodisc filter having pore size 0.02 μm. The porous MOF membrane filters gold nanoparticles with a cutoff of ∼2.4 nm.


ACS Nano | 2018

Highly Oriented Monolayer Graphene Grown on a Cu/Ni(111) Alloy Foil

Ming Huang; Mandakini Biswal; Hyo Ju Park; Sunghwan Jin; Deshun Qu; Seokmo Hong; Zhili Zhu; Lu Qiu; Da Luo; Xiaochi Liu; Zheng Yang; Zhong-Liu Liu; Yuan Huang; Hyunseob Lim; Won Jong Yoo; Feng Ding; Yeliang Wang; Zonghoon Lee; Rodney S. Ruoff

Fast-growth of single crystal monolayer graphene by CVD using methane and hydrogen has been achieved on homemade single crystal Cu/Ni(111) alloy foils over large area. Full coverage was achieved in 5 min or less for a particular range of composition (1.3 at.% to 8.6 at.% Ni), as compared to 60 min for a pure Cu(111) foil under identical growth conditions. These are the bulk atomic percentages of Ni, as a superstructure at the surface of these foils with stoichiometry Cu6Ni1 (for 1.3 to 7.8 bulk at.% Ni in the Cu/Ni(111) foil) was discovered by low energy electron diffraction (LEED). Complete large area monolayer graphene films are either single crystal or close to single crystal, and include folded regions that are essentially parallel and that were likely wrinkles that fell over to bind to the surface; these folds are separated by large, wrinkle-free regions. The folds occur due to the buildup of interfacial compressive stress (and its release) during cooling of the foils from 1075 °C to room temperature. The fold heights measured by atomic force microscopy (AFM) and scanning tunneling microscopy (STM) prove them to all be 3 layers thick, and scanning electron microscopy (SEM) imaging shows them to be around 10 to 300 nm wide and separated by roughly 20 μm. These folds are always essentially perpendicular to the steps in this Cu/Ni(111) substrate. Joining of well-aligned graphene islands (in growths that were terminated prior to full film coverage) was investigated with high magnification SEM and aberration-corrected high-resolution transmission electron microscopy (TEM) as well as AFM, STM, and optical microscopy. These methods show that many of the join regions have folds, and these arise from interfacial adhesion mechanics (they are due to the buildup of compressive stress during cool-down, but these folds are different than for the continuous graphene films-they occur due to weak links in terms of the interface mechanics). Such Cu/Ni(111) alloy foils are promising substrates for the large-scale synthesis of single-crystal graphene film.


Advanced Materials | 2018

Orientation‐Dependent Strain Relaxation and Chemical Functionalization of Graphene on a Cu(111) Foil

Bao-Wen Li; Da Luo; Liyan Zhu; Xu Zhang; Sunghwan Jin; Ming Huang; Feng Ding; Rodney S. Ruoff

Epitaxial graphene grown on single crystal Cu(111) foils by chemical vapor deposition is found to be free of wrinkles and under biaxial compressive strain. The compressive strain in the epitaxial regions (0.25-0.40%) is higher than regions where the graphene is not epitaxial with the underlying surface (0.20-0.25%). This orientation-dependent strain relaxation is through the loss of local adhesion and the generation of graphene wrinkles. Density functional theory calculations suggest a large frictional force between the epitaxial graphene and the Cu(111) substrate, and this is therefore an energy barrier to the formation of wrinkles in the graphene. Enhanced chemical reactivity is found in epitaxial graphene on Cu(111) foils as compared to graphene on polycrystalline Cu foils for certain chemical reactions. A higher compressive strain possibly favors lowering the formation energy and/or the energy gap between the initial and transition states, either of which can lead to an increase in chemical reactivity.


ACS Nano | 2018

Freeze-Casting Produces a Graphene Oxide Aerogel with a Radial and Centrosymmetric Structure

Chunhui Wang; Xiong Chen; Bin Wang; Ming Huang; Bo Wang; Yi Jiang; Rodney S. Ruoff

We report the assembly of graphene oxide (G-O) building blocks into a vertical and radially aligned structure by a bidirectional freeze-casting approach. The crystallization of water to ice assembles the G-O sheets into a structure, a G-O aerogel whose local structure mimics turbine blades. The centimeter-scale radiating structure in this aerogel has many channels whose width increases with distance from the center. This was achieved by controlling the formation of the ice crystals in the aqueous G-O dispersion that grew radially in the shape of lamellae during freezing. Because the shape and size of ice crystals is influenced by the G-O sheets, different additives (ethanol, cellulose nanofibers, and chitosan) that can form hydrogen bonds with H2O were tested and found to affect the interaction between the G-O and formation of ice crystals, producing ice crystals with different shapes. A G-O/chitosan aerogel with a spiral pattern was also obtained. After chemical reduction of G-O, our aerogel exhibited elasticity and absorption capacity superior to that of graphene aerogels with traditional pore structures made by conventional freeze-casting. This methodology can be expanded to many other configurations and should widen the use of G-O (and reduced G-O and graphenic) aerogels.

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Rodney S. Ruoff

Ulsan National Institute of Science and Technology

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Da Luo

Ulsan National Institute of Science and Technology

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Bao-Wen Li

Ulsan National Institute of Science and Technology

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Feng Ding

Ulsan National Institute of Science and Technology

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Xianjue Chen

Ulsan National Institute of Science and Technology

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Zonghoon Lee

Ulsan National Institute of Science and Technology

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Won Jong Yoo

Sungkyunkwan University

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