62,263 results match your criteria graphene

Determination of Mn(II) and Mn(VII) in beverage samples using magnetic dispersive micro-solid phase extraction coupled with solidified floating organic drop microextraction followed by graphite furnace atomic absorption spectrometry.

Food Chem 2021 Apr 28;359:129958. Epub 2021 Apr 28.

College of Food Science and Engineering, Wuhan Polytechnic University, Wuhan 430023, PR China.

Magnetic dispersive micro-solid phase extraction (MDMSPE) was coupled with solidified floating organic drop microextraction (SFODME) for direct separation and preconcentration of Mn(II) and Mn(VII) before graphite furnace atomic absorption spectrometry determination. MDMSPE involved use of magnetic ZnFeO nanotubes for adsorbing Mn(VII). Sorbent was isolated from aqueous phase by an external magnet. Read More

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Screening of hydrogen bonding interactions by a single layer graphene.

Nanoscale 2021 May 6;13(17):8098-8106. Epub 2021 Apr 6.

School of Polymer Science and Polymer Engineering, University of Akron, Akron, OH 44325, USA.

A single layer of graphene when transferred to a solid substrate has the ability to screen or transmit interactions from the underlying substrate, which has direct consequences in applications of this 2D material to flexible electronics and sensors. Previous reports using a multitude of techniques present contradictory views on graphene's ability to screen or transmit van der Waals (vdW) and polar interactions. In the present study, we use interface-sensitive spectroscopy to demonstrate that a single layer graphene is opaque to hydrogen bonding interactions (a subset of acid-base interactions), answering a question that has remained unresolved for a decade. Read More

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Magnetic Graphene Oxide-Based Affinity Surface-Assisted Laser Desorption/Ionization Mass Spectrometry for Screening of Aflatoxin B1 from Complex Samples.

Anal Chem 2021 May 6. Epub 2021 May 6.

Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan.

Aflatoxin B1 (AFB1), commonly found in agriculture products, has been considered as a carcinogen. Thus, to develop analytical methods that can be used to rapidly screen the presence of AFB1 in complex samples is important. Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) uses inorganic materials as assisting materials to facilitate desorption/ionization of analytes. Read More

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Enhanced Electroactivity, Mechanical Properties, and Printability through the Addition of Graphene Oxide to Photo-Cross-linkable Gelatin Methacryloyl Hydrogel.

ACS Biomater Sci Eng 2021 May 6. Epub 2021 May 6.

ARC Centre of Excellence for Electromaterials Science, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Melbourne, Victoria 3122, Australia.

The human tissues most sensitive to electrical activity such as neural and muscle tissues are relatively soft, and yet traditional conductive materials used to interface with them are typically stiffer by many orders of magnitude. Overcoming this mismatch, by creating both very soft and electroactive materials, is a major challenge in bioelectronics and biomaterials science. One strategy is to imbue soft materials, such as hydrogels, with electroactive properties by adding small amounts of highly conductive nanomaterials. Read More

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Fabrication of magnetic FeO@SiO@BiOCO/rGO composite for enhancing its photocatalytic performance for organic dyes and recyclability.

Environ Sci Pollut Res Int 2021 May 6. Epub 2021 May 6.

School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan, 411201, China.

A novel magnetic FeO@SiO@BiOCO/rGO composite comprising of uniform core-shell-structured FeO@SiO@BiOCO microspheres mounted on reduced graphene oxide (rGO) sheets was successfully fabricated by using a facile hydrothermal method. The adsorption-desorption isotherm of FeO@SiO@BiOCO/rGO belonged to type IV with an H4-type hysteresis loop. The specific surface areas and magnetization saturation value (M) of FeO@SiO@BiOCO/rGO (x = 0. Read More

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Constructing Densely Compacted Graphite/Si/SiO Ternary Composite Anodes for High-Performance Li-Ion Batteries.

ACS Appl Mater Interfaces 2021 May 6. Epub 2021 May 6.

State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, China.

Graphite has dominated the market of anode materials for lithium-ion batteries in applications such as consumer electronic devices and electric vehicles. As commercial graphite anodes are approaching their theoretical capacity, significant efforts have been dedicated towards higher capacity by blending capacity-enhancing additives (e.g. Read More

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Lowly-aggregated perylene diimide as a near-infrared electrochemiluminescence luminophore for ultrasensitive immunosensors at low potentials.

Analyst 2021 May 6. Epub 2021 May 6.

Chemistry and Chemical Engineering College, Liaocheng University, Liaocheng, 252059, China.

In the electrochemiluminescence (ECL) field, most reported luminophores were focused on high-triggering potential and short wavelength, which was adverse for the ECL theory study and application at low potentials. Perylene diimide derivatives could emit near-infrared (NIR) ECL at low-triggering potential; however, they are always highly aggregated into a microrod structure and stacked together, which largely limited their application in biological fields such as bio-sensing and bio-imaging. To overcome these obstacles, we designed a novel perylene diimide molecule, namely N,N'-dicaproate sodium-3,4,9,10-perylenedicarboximide (PDI-COONa). Read More

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Fabrication of 3D-Printed Ceramic Structures for Portable Solar Desalination Devices.

ACS Appl Mater Interfaces 2021 May 6. Epub 2021 May 6.

Department of Materials Science and Engineering, Faculty of Engineering, National University of Singapore, 9 Engineering Drive 1, Block EA, Singapore 117575, Singapore.

This paper proposes the fabrication process of the first fully 3D-printed ceramic core structures for portable solar desalination devices optimized to tackle water scarcity from an energy and sustainability perspective. Robocasting, a 3D printing technique, is utilized to fabricate a fully ceramic structure of an integrated solar absorber/thermal insulator/water transporter based on the two-layered structure of modified graphene on silica (MG@Silica) and the porous silica structure. Robocasting has demonstrated its flexibility in tailoring structural designs, combining nanopores and microchannels that exhibit uniform water transport delivery and thermal insulation. Read More

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Odd Integer Quantum Hall States with Interlayer Coherence in Twisted Bilayer Graphene.

Nano Lett 2021 May 6. Epub 2021 May 6.

Max-Planck-Institut für Festköperforschung, 70569 Stuttgart, Germany.

We report on the quantum Hall effect in two stacked graphene layers rotated by 2°. The tunneling strength among the layers can be varied from very weak to strong via the mechanism of magnetic breakdown when tuning the density. Odd-integer quantum Hall physics is not anticipated in the regime of suppressed tunneling for balanced layer densities, yet it is observed. Read More

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Tunneling current modulation in atomically precise graphene nanoribbon heterojunctions.

Nat Commun 2021 May 5;12(1):2542. Epub 2021 May 5.

II. Physikalisches Institut, Universität zu Köln, Köln, Germany.

Lateral heterojunctions of atomically precise graphene nanoribbons (GNRs) hold promise for applications in nanotechnology, yet their charge transport and most of the spectroscopic properties have not been investigated. Here, we synthesize a monolayer of multiple aligned heterojunctions consisting of quasi-metallic and wide-bandgap GNRs, and report characterization by scanning tunneling microscopy, angle-resolved photoemission, Raman spectroscopy, and charge transport. Comprehensive transport measurements as a function of bias and gate voltages, channel length, and temperature reveal that charge transport is dictated by tunneling through the potential barriers formed by wide-bandgap GNR segments. Read More

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Density-independent plasmons for terahertz-stable topological metamaterials.

Proc Natl Acad Sci U S A 2021 May;118(19)

Beijing Computational Science Research Center, 100193 Beijing, China;

To efficiently integrate cutting-edge terahertz technology into compact devices, the highly confined terahertz plasmons are attracting intensive attention. Compared to plasmons at visible frequencies in metals, terahertz plasmons, typically in lightly doped semiconductors or graphene, are sensitive to carrier density () and thus have an easy tunability, which leads to unstable or imprecise terahertz spectra. By deriving a simplified but universal form of plasmon frequencies, here, we reveal a unified mechanism for generating unusual -independent plasmons (DIPs) in all topological states with different dimensions. Read More

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Charged skyrmions and topological origin of superconductivity in magic-angle graphene.

Sci Adv 2021 May 5;7(19). Epub 2021 May 5.

Department of Physics, Harvard University, Cambridge, MA 02138, USA.

Topological solitons, a class of stable nonlinear excitations, appear in diverse domains as in the Skyrme model of nuclear forces. Here, we argue that similar excitations play an important role in a remarkable material obtained on stacking and twisting two sheets of graphene. Close to a magic twist angle, insulating behavior is observed, which gives way to superconductivity on doping. Read More

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Interaction with teichoic acids contributes to highly effective antibacterial activity of graphene oxide on Gram-positive bacteria.

J Hazard Mater 2021 Jun 5;412:125333. Epub 2021 Feb 5.

Institut für Biologie, Freie Universität Berlin, Berlin D-14195, Germany.

Graphene oxide (GO) has high-efficient antibacterial activity to diverse pathogenic bacteria. However, the detailed antibacterial mechanism of GO is not fully clear. Herein the antibacterial properties of GO against model Gram-positive (Gram+) (Staphylococcus aureus and Staphylococcus epidermidis) and Gram-negative (Gram-) bacteria (Pseudomonas aeruginosa and Escherichia coli) were compared by plate count method. Read More

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A Novel Nonenzymatic Ascorbic Acid Electrochemical Sensor Based on Gold Nanoparticals-Chicken Egg White-Copper Phosphate-Graphene Oxide Hybrid Nanoflowers.

Nanotechnology 2021 May 5. Epub 2021 May 5.

Shaanxi University of Science and Technology Xi'an Campus, Xi'an, Shaanxi, CHINA.

Au-CEW-Cu3(PO4)2-GO nanoflowers (HNFs), which were assembled of gold nanoparticals (Au NPs), chicken egg white (CEW), copper phosphate (Cu3(PO4)2) and graphene oxide (GO) together to form a flower-like organic/inorganic hybrid nanocomposite, were synthesized through a simple and gentle one-pot co-precipitation method. The prepared samples were well characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray spectrometer (EDX), X-ray diffraction (XRD) and Raman spectrometer. The prepared Au-CEW-Cu3(PO4)2-GO HNFs was used to modify glassy carbon electrode (GCE) to fabricate an electrochemical sensor for detection of ascorbic acid (AA). Read More

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Pristine Graphene Insertion at the Metal/Semiconductor Interface to Minimize Metal-Induced Gap States.

ACS Appl Mater Interfaces 2021 May 5. Epub 2021 May 5.

Department of Chemical Engineering Pohang University of Science and Technology 77 Cheongam-Ro, Nam-Gu, Pohang 37673, Republic of Korea.

Metal (M) contact with a semiconductor (S) introduces metal-induced gap states (MIGS), which makes it difficult to study the intrinsic electrical properties of S. A bilayer of metal with graphene (Gr), ., a M/Gr bilayer, may form a contact with S to minimize MIGS. Read More

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Imaging Dual-Moiré Lattices in Twisted Bilayer Graphene Aligned on Hexagonal Boron Nitride Using Microwave Impedance Microscopy.

Nano Lett 2021 May 5. Epub 2021 May 5.

Department of Physics and Astronomy, University of California, Riverside, California 92521, United States.

Moiré superlattices (MSLs) formed in van der Waals materials have become a promising platform to realize novel two-dimensional electronic states. Angle-aligned trilayer structures can form two sets of MSLs which could potentially interfere. In this work, we directly image the moiré patterns in both monolayer and twisted bilayer graphene aligned on hexagonal boron nitride (hBN), using combined scanning microwave impedance microscopy and conductive atomic force microscopy. Read More

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TEMPO-Oxidized Bacterial Cellulose Nanofibers/Graphene Oxide Fibers for Osmotic Energy Conversion.

ACS Appl Mater Interfaces 2021 May 5. Epub 2021 May 5.

State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, P. R. China.

The large osmotic energy between river water and seawater is an inexhaustible blue energy source; however, the complicated manufacturing methods used for ion-exchange devices hinder the development of reverse electrodialysis (RED). Here, we use a wet-spinning method to continuously spin meter-scale 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized bacterial cellulose (TOBC) nanofiber filaments, which are then used to construct nanochannels for osmotic energy conversion. These are then used to build a nacre-like structure by adding graphene oxide (GO), which provides narrow nanochannels in one-dimensional and two-dimensional nanofluid systems for rapid ion transport. Read More

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Fiber optic hydrogen sensor based on a Fabry-Perot interferometer with a fiber Bragg grating and a nanofilm.

Lab Chip 2021 May;21(9):1752-1758

Shenzhen Key Laboratory of Photonic Devices and Sensing Systems for Internet of Things, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China. and Guangdong and Hong Kong Joint Research Centre for Optical Fibre Sensors, Shenzhen University, Shenzhen 518060, China.

Hydrogen is widely used in industrial production and clinical medicine, and as fuel. Hydrogen becomes explosive when the hydrogen-air mixture ranges from 4 to 76 vol%; thus, a rapid hydrogen concentration measurement is particularly important in practical applications. We present a novel fiber optic hydrogen sensor with fast response fabricated from a graphene-Au-Pd sandwich nanofilm and an ultrashort fiber Bragg grating. Read More

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Enhanced optical limiting and hydrogen evolution of graphene oxide nanohybrids covalently functionalized by covalent organic polymer based on porphyrin.

Dalton Trans 2021 May 4. Epub 2021 May 4.

College of Physical Science and Technology, Soochow University, Suzhou, 215006, China.

Herein, we report a novel graphene oxide (GO) nanohybrid covalently functionalized by covalent organic polymer (COP) based on porphyrin (GO-TPPCOP), as the optical limiter and hydrogen evolution reaction (HER) electrocatalyst. The GO-TPPCOP nanohybrid exhibits markedly enhanced optical limiting and HER activity over that of TPP, GO and TPPCOP alone. More importantly, the optical limiting property and HER activity of GO-TPPCOP nanohybrid are comparable to the state-of-the-art activity of materials from some previous reports. Read More

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Graphene-based materials: the key for the successful application of pHEMA as a blood-contacting device.

Biomater Sci 2021 May;9(9):3362-3377

INEB - Instituto de Engenharia Biomédica, Universidade do Porto, Portugal. and i3S - Instituto de Inovação e Investigação em Saúde, Universidade do Porto, Portugal.

Thrombosis and infection are the leading causes of blood-contacting device (BCD) failure, mainly due to the poor performance of existing biomaterials. Poly(2-hydroxyethyl methacrylate) (pHEMA) has excellent hemocompatibility but the weak mechanical properties impair its use as a bulk material for BCD. As such, pHEMA has been explored as a coating, despite the instability and difficulty of attachment to the underlying polymer compromise its success. Read More

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Utilization of rGO-PEI-supported AgNPs for sensitive recognition of deltamethrin in human plasma samples: A new platform or the biomedical analysis of pesticides in human biofluids.

J Mol Recognit 2021 May 4:e2900. Epub 2021 May 4.

Pharmaceutical Analysis Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.

In this study, the rGO-PEI-AgNPs sensor was designed as a new effective platform to sensitive monitoring of deltamethrin in human plasma samples. For this purpose, reduced graphene oxide (rGO)-supported polyethylenimine (PEI) was used as a suitable substrate for dispersion of silver nanoparticles (AgNPs) as amplification and catalytic element. Therefore, a novel interface (rGO-PEI-AgNPs) was prepared by the fully electrochemical method on the surface of glassy carbon electrodes. Read More

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Multifunctional graphene-based nanocomposites for simultaneous enhanced photocatalytic degradation and photothermal antibacterial activity by visible light.

Environ Sci Pollut Res Int 2021 May 4. Epub 2021 May 4.

College of International Education, Zhongyuan University of Technology, Zhengzhou, 450007, People's Republic of China.

A new strategy for the wastewater treatment was proposed by combining polyvinylpyrrolidone-functionalized silver nanoparticles with reduced graphene oxide (AgNPs-PVP@rGO) as a visible light-triggered photoactive nanocomposite. The nanocomposite with enhanced photocatalytic degradation and photothermal antibacterial activity can simultaneously decrease the content of organic pollutants and bacteria in the wastewater under visible light irradiation. The efficiency of photocatalytic degradation can be significantly improved by the conjugation of AgNPs onto the rGO surface. Read More

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Diamine vapor treatment of viscoelastic graphene oxide liquid crystal for gas barrier coating.

Sci Rep 2021 May 4;11(1):9518. Epub 2021 May 4.

Department of Chemical and Biomolecular Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722, Republic of Korea.

A layered graphene oxide/ethylenediamine (GO/EDA) composite film was developed by exposing aqueous GO liquid crystal (GOLC) coating to EDA vapor and its effects on the gas barrier performance of GO film were systematically investigated. When a GO/EDA coating with a thickness of approximately 1 μm was applied to a neat polyethylene terephthalate (PET) film, the resultant film was highly impermeable to gas molecules, particularly reducing the gas permeance up to 99.6% for He and 98. Read More

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Visualizing delocalized correlated electronic states in twisted double bilayer graphene.

Nat Commun 2021 May 4;12(1):2516. Epub 2021 May 4.

Department of Physics, University of California, Berkeley, CA, USA.

The discovery of interaction-driven insulating and superconducting phases in moiré van der Waals heterostructures has sparked considerable interest in understanding the novel correlated physics of these systems. While a significant number of studies have focused on twisted bilayer graphene, correlated insulating states and a superconductivity-like transition up to 12 K have been reported in recent transport measurements of twisted double bilayer graphene. Here we present a scanning tunneling microscopy and spectroscopy study of gate-tunable twisted double bilayer graphene devices. Read More

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Image-charge effects on ion adsorption near aqueous interfaces.

Proc Natl Acad Sci U S A 2021 May;118(19)

Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125;

Electrostatic interactions near surfaces and interfaces are ubiquitous in many fields of science. Continuum electrostatics predicts that ions will be attracted to conducting electrodes but repelled by surfaces with lower dielectric constant than the solvent. However, several recent studies found that certain "chaotropic" ions have similar adsorption behavior at air/water and graphene/water interfaces. Read More

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Electrical and visible light dual-responsive ZnO nanocomposite with multiple wound healing capability.

Mater Sci Eng C Mater Biol Appl 2021 May 26;124:112066. Epub 2021 Mar 26.

College of Chemistry, Nanchang University, Nanchang, Jiangxi 330088, PR China; The National Engineering Research Center for Bioengineering Drugs and the Technologies, Institute of Translational Medicine, Nanchang University, Nanchang, Jiangxi 330088, PR China. Electronic address:

The healing process of open wounds is a competition between cells and bacteria. Therefore, a strategy that can quickly remove bacteria and promote cell proliferation to accelerate wound healing is urgently needed. Inspired by photoelectric synergy tactics, we improved both the optical and electrical response of zinc oxide (ZnO) through the modification of polydopamine (PDA) and reduced graphene oxide (rGO), thus obtaining a ZnO composite named PDA-rGO-ZnO (PrZ). Read More

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Synthesis of Multilayered DLC Films with Wear Resistance and Antiseizure Properties.

Materials (Basel) 2021 Apr 29;14(9). Epub 2021 Apr 29.

Institute of Innovative Research (IIR), Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, Kanagawa 226-8503, Japan.

Diamond-like carbon (DLC) films have attracted considerable interest for application as protective films in diverse industrial parts. This is attributed to their desirable characteristics, such as high hardness, low coefficient of friction, gas-barrier properties, and corrosion resistance. Antiseizure properties, in addition to wear resistance, are required during the die molding of polymer and polymer-matrix composite parts. Read More

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Chitosan/Silver Nanoparticle/Graphene Oxide Nanocomposites with Multi-Drug Release, Antimicrobial, and Photothermal Conversion Functions.

Materials (Basel) 2021 Apr 30;14(9). Epub 2021 Apr 30.

School of Mechanical & Aerospace Engineering, Queens University Belfast, Belfast BT9 5AH, UK.

In this work, we designed and fabricated a multifunctional nanocomposite system that consists of chitosan, raspberry-like silver nanoparticles, and graphene oxide. The room temperature atmospheric pressure microplasma (RT-APM) process provides a rapid, facile, and environmentally-friendly method for introducing silver nanoparticles into the composite system. Our composite can achieve a pH controlled single and/or dual drug release. Read More

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Graphitized-rGO/Polyimide Aerogel as the Compressible Thermal Interface Material with Both High In-Plane and Through-Plane Thermal Conductivities.

Materials (Basel) 2021 Apr 30;14(9). Epub 2021 Apr 30.

Department of Optoelectronic Information Science and Engineering, College of Electronic and Opitical Engineering, Nanjing University of Posts&Telecommunications, Nanjing 210023, China.

Reduced graphene oxide (rGO) aerogels with a three-dimensional (3D) interconnected network provides continuous heat transport paths in multi-directions. However, the high porosity of rGO aerogels commonly leads to very low thermal conductivity (TC), and defects and grain boundaries of rGO sheets result in a high extent of phonon scattering, which is far from satisfying the requirement of thermal interface materials (TIMs). Here, a compressible graphitized-rGO/polyimide (g-rGO/PI) aerogel was prepared by the ice-template method and "molecular welding" strategy. Read More

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Enhanced NO Sensing Performance of Graphene with Thermally Induced Defects.

Materials (Basel) 2021 Apr 30;14(9). Epub 2021 Apr 30.

Sensor System Research Center, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.

This paper demonstrates the enhanced NO sensing performance of graphene with defects generated by rapid thermal annealing (RTA). A high temperature of RTA (300-700 °C) was applied to graphene under an argon atmosphere to form defects on sp carbon lattices. The density of defects proportionally increased with increasing the RTA temperature. Read More

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