Transfer-free chemical vapor deposition of graphene on silicon substrate at atmospheric pressure: A sacrificial catalyst

Naghdi, Samira,Rhee, Kyong Yop,Park, Soo Jin Elsevier 2018 THIN SOLID FILMS - Vol.657 No.-

<P><B>Abstract</B></P> <P>Transfer-free synthesis of graphene on dielectric substrates is highly desirable, but remains challenging. Here, using a thin sacrificial platinum (Pt) layer as a catalyst, graphene was deposited on silicon (Si) substrate through a simple and transfer-free synthesis method. During graphene growth, the Pt layer evaporated, resulting in direct deposition of graphene on the Si substrate. In this work, different growth conditions of graphene were optimized. Raman spectra of the produced graphene indicated that the obtained graphene was bilayer. The sheet resistance obtained from four-point probe measurements demonstrated that the deposited graphene had high conductivity. Reflectance spectroscopy of graphene-coated Si showed a decrease in reflectance across the wavelength range of 200–800 nm, indicating that the graphene coating on the Si surface had antireflective capabilities.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Use of Pt as a sacrificial catalyst for deposition of graphene for the first time </LI> <LI> Direct deposition of graphene on the Si substrate without further transfer methods </LI> <LI> Optimization of different growth conditions of graphene on Pt thin film </LI> <LI> Deposition of graphene on Si surface demonstrated low sheet resistance. </LI> <LI> Antireflection capability of graphene coating on Si surface in UV–Visible spectra </LI> </UL> </P>

Oxidation resistance of graphene-coated molybdenum: Effects of pre-washing and hydrogen flow rate

Naghdi, S.,Rhee, K.Y.,Park, S.J. MPR Pub. Services 2017 International journal of refractory metals & hard Vol.65 No.-

<P>An effective approach to protect metal surfaces against oxidation and corrosion is of great importance for various practical and industrial applications. Current solutions, however, typically introduce several undesired effects, including increased thickness and changes in the metal's physical properties. Here, we demonstrate the formation of a graphene coating using an atmospheric pressure chemical vapor deposition (APCVD) technique combined with a specifically tuned hydrogen flow rate (200, 500, and 1000 sccm) and an acid solution for pre-washing. The pre-washing process consists of acid etching by three different acids that help to remove impurities. These impurities include native molybdenum oxide and impurities that can act as nucleation centers for multilayer graphene. The specimens were characterized by Raman spectroscopy, optical microscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy. Results indicate that the molybdenum surface was well protected from oxidation, even after heating to a temperature of 300 degrees C in air for 2 h. (C) 2016 Elsevier Ltd. All rights reserved.</P>

Chemical vapour deposition at atmospheric pressure of graphene on molybdenum foil: Effect of annealing time on characteristics and corrosion stability of graphene coatings

Naghdi, Samira,Jevremović,, Ivana,Miš,ković,-Stanković,, Vesna,Rhee, Kyong Yop Elsevier 2016 Corrosion science Vol.113 No.-

<P><B>Abstract</B></P> <P>In this work, the effect of pre-annealing of Mo substrate on the quality of graphene layers grown by chemical vapour deposition was investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. Moreover, different electrochemical techniques were employed to investigate the corrosion stability of the graphene coated Mo in 0.1M NaCl. Longer annealing time resulted in less defective graphene coatings with fewer layers. Graphene coating on the annealed Mo provided better protection against corrosion during the initial exposure times, while after prolonged exposure times, both graphene coatings on annealed and non-annealed Mo exhibited nearly the same corrosion inhibitive properties.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Atmospheric pressure chemical vapor deposition of graphene on molybdenum foils. </LI> <LI> Quality and domain size of graphene layers increased with longer annealing times. </LI> <LI> The number of graphene layers decreased with longer annealing times. </LI> <LI> Graphene coatings on molybdenum foils exhibited corrosion inhibitive properties. </LI> </UL> </P>

A catalytic, catalyst-free, and roll-to-roll production of graphene via chemical vapor deposition: Low temperature growth

Naghdi, Samira,Rhee, Kyong Yop,Park, Soo Jin Elsevier 2018 Carbon Vol.127 No.-

<P><B>Abstract</B></P> <P>The application of graphene as a two-dimensional nano-material has gained wide interest in different research areas, but its use is still novel for scientists. There has been continuous progress in the development of different synthesis methods to readily produce graphene at a lower cost. Chemical vapor deposition (CVD) is a powerful process to produce graphene, and it is accompanied by other methods. The present article provides a detailed review of the synthesis of graphene by a CVD process at temperatures below 1000 °C (LTCVD). In this work, challenges related to the use of plasma-assisted CVD, different carbon precursors, and catalysts are discussed.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Comprehensive electrochemical study on corrosion performance of graphene coatings deposited by chemical vapour deposition at atmospheric pressure on platinum-coated molybdenum foil

Naghdi, Samira,Neš,ović,, Katarina,Miš,ković,-Stanković,, Vesna,Rhee, Kyong Yop Pergamon Press 2018 Corrosion science Vol.130 No.-

<P><B>Abstract</B></P> <P>In this work, we present the results of electrochemical, Raman, FE-SEM/EDS, and XPS studies of graphene coatings deposited by chemical vapour deposition at atmospheric pressure on Mo foil and Pt-coated Mo foil as catalysts. The results showed that the graphene coating synthesized on Pt-coated molybdenum foil was bi-layer and had fewer defects, while the graphene coating on Mo foil was few-layer with more defects. The corrosion studies indicated that both graphene coatings on bare Mo and Pt-coated Mo exhibited good protective properties and can act as a barrier against corrosion in 0.1M NaCl.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Graphene chemical vapour deposition (CVD) at atmospheric pressure on molybdenum. </LI> <LI> Platinum thin film on molybdenum provided catalytic effect for CVD of graphene. </LI> <LI> Graphene coating on Pt-coated Mo samples had larger grain size and fewer defects. </LI> <LI> Both graphene coatings on Mo and Pt-coated Mo exhibited corrosion protection. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Altering the structure and properties of iron oxide nanoparticles and graphene oxide/iron oxide composites by urea

Naghdi, S.,Rhee, K.Y.,Jaleh, B.,Park, S.J. New York] ; North-Holland 2016 APPLIED SURFACE SCIENCE - Vol.364 No.-

Iron oxide (Fe<SUB>2</SUB>O<SUB>3</SUB>) nanoparticles were grown on graphene oxide (GO) using a simple microwave-assisted method. The effects of urea concentration on Fe<SUB>2</SUB>O<SUB>3</SUB> nanoparticles and GO/Fe<SUB>2</SUB>O<SUB>3</SUB> composite were examined. The as-prepared samples were characterized using X-ray powder diffraction, Raman spectroscopy, and transmission electron microscopy. The Fe<SUB>2</SUB>O<SUB>3</SUB> nanoparticles were uniformly developed on GO sheets. The results showed that urea affects both Fe<SUB>2</SUB>O<SUB>3</SUB> morphology and particle size. In the absence of urea, the Fe<SUB>2</SUB>O<SUB>3</SUB> nanostructures exhibited a rod-like morphology. However, increasing urea concentration altered the morphology and decreased the particle size. The Raman results of GO/Fe<SUB>2</SUB>O<SUB>3</SUB> showed that the intensity ratio of D band to G band (I<SUB>D</SUB>/I<SUB>G</SUB>) was decreased by addition of urea, indicating that urea can preserve the GO sheets during synthesis of the composite from exposing more defects. The surface area and thermal stability of GO/Fe<SUB>2</SUB>O<SUB>3</SUB> and Fe<SUB>2</SUB>O<SUB>3</SUB> were compared using the Brunauer-Emmett-Teller method and thermal gravimetric analysis, respectively. The results showed that the increased concentration of urea induced a larger surface area with more active sites in the Fe<SUB>2</SUB>O<SUB>3</SUB> nanoparticles. However, the increase in urea concentration led to decreased thermal stability of the Fe<SUB>2</SUB>O<SUB>3</SUB> nanoparticles. The magnetic properties of Fe<SUB>2</SUB>O<SUB>3</SUB> nanoparticles were characterized by a vibrating sample magnetometer and results revealed that the magnetic properties of Fe<SUB>2</SUB>O<SUB>3</SUB> nanoparticles are affected by the morphology.

Shape-Dependent Magnetic Properties and Phase Transformation of Annealed Iron Oxide Nanoparticles

Naghdi, S.,Rhee, K. Y.,Park, S. J. Springer New York LLC 2017 JOM Vol. No.

Threshold creep behaviour of an aged Mg–Zn–Ca alloy

Naghdi, F.,Mahmudi, R.,Kang, J.Y.,Kim, H.S. Elsevier Sequoia 2017 Materials science & engineering Structural materia Vol.696 No.-

<P><B>Abstract</B></P> <P>The creep characteristics of an aged Mg–4Zn–0.5Ca (wt%) were investigated using impression creep tests in the temperature range of 423–523K and under punch stresses in the range of 225–750MPa for dwell times up to 3600s. The creep behaviour of the alloy was found to be associated with a threshold stress and well-described by the Garofalo hyperbolic sine equation modified for the threshold stress concept. The stress exponent of 5 and the activation energy for creep close to that of pipe diffusion in Mg, i.e. 97kJmol<SUP>−1</SUP>, implies that dislocation climb controlled by diffusion through dislocation cores is the dominant rate-controlling mechanism. However, fitting the Garofalo equation to the experimental data showed that power-law breakdown (PLB) occurred in the material at high stress levels, especially at low temperatures. The threshold stress, appeared at low stress levels and low temperatures, was attributed to the nano-precipitates formed in the microstructure during aging treatment. The threshold stress was temperature-dependent, decreasing with increasing testing temperature and disappearing at about 575K.</P>

Microstructure and high-temperature mechanical properties of the Mg-4Zn-0.5Ca alloy in the as-cast and aged conditions

Naghdi, F.,Mahmudi, R.,Kang, J.Y.,Kim, H.S. Elsevier Sequoia 2016 Materials science & engineering. properties, micro Vol.649 No.-

<P>Shear punch test (SPT) was employed to study the high temperature mechanical properties of an Mg-4Zn-0.5Ca (wt%) alloy in the as-cast and aged conditions in the temperature range 150-250 degrees C. The microstructure of the as-cast alloy consisted of alpha-Mg matrix with some Ca2Mg6Zn3 and MgZn second phase particles distributed in the interdendritic regions. Aging treatment resulted in the formation of equiaxed alpha-Mg grains together with coarse ca(2)Mg(6)Zn(3) phase in the form of a semi-continuous network at the grain boundaries and triple points, while nano-sized Mg4Zn2, MgZn2, and Ca2Mg6Zn3 precipitates formed in the grain interiors. These phases have high thermal stabilities that could improve the hightemperature mechanical properties of the tested alloy after aging treatment. (C) 2015 Elsevier B.V. All rights reserved.</P>

<i>Cuscuta reflexa</i> leaf extract mediated green synthesis of the Cu nanoparticles on graphene oxide/manganese dioxide nanocomposite and its catalytic activity toward reduction of nitroarenes and organic dyes

Naghdi, Samira,Sajjadi, Mohaddeseh,Nasrollahzadeh, Mahmoud,Rhee, Kyong Yop,Sajadi, S. Mohammad,Jaleh, Babak Elsevier 2018 JOURNAL- TAIWAN INSTITUTE OF CHEMICAL ENGINEERS Vol.86 No.-

<P><B>Abstract</B></P> <P>The present study reports an efficient, surfactant-free, novel and facile green method for the immobilization of Cu NPs on the surface of the graphene oxide/manganese dioxide (GO/MnO<SUB>2</SUB>) nanocomposite using <I>Cuscuta reflexa</I> leaf extract<I>.</I> In fact the phytochemical content of the plant extract are responsible to biosynthesis of Cu nanoparticles (NPs) and their stabilization by functionalizing the surface of graphene. The Cu NPs were characterized by Fourier transformed infrared spectroscopy (FT-IR) and UV–visible spectroscopy. MnO<SUB>2</SUB> NPs and GO/MnO<SUB>2</SUB> nanocomposite were prepared by using a simple one-step hydrothermal method without using any toxic solvent. The synthesized GO/MnO<SUB>2</SUB> and Cu/GO/MnO<SUB>2</SUB> nanocomposites were characterized using X-ray diffraction analysis (XRD), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM) images, Brunauer–Emmett–Teller (BET), Thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), energy-dispersive X-ray spectroscopy (EDS), elemental mapping and FT-IR spectroscopy. The synthesized Cu/GO/MnO<SUB>2</SUB> nanocomposite was then successfully used as a reusable catalyst for the reduction of 2,4-dinitrophenilhydrazine (2,4-DNPH), 4-nitrophenol (4-NP), Rhodamine B (RhB), Congo red (CR), methyl orange (MO) and methylene blue (MB) using NaBH<SUB>4</SUB> in water at ambient temperature. This method is clean and environmentally friendly without using any toxic reducing agents.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Green synthesis of the Cu/GO/MnO<SUB>2</SUB> nanocomposite using <I>Cuscuta reflexa</I> leaf extract. </LI> <LI> Reduction of 4-NP, 2,4-DNPH, CR, MO, MB and RhB in water. </LI> <LI> Characterization of the GO/MnO<SUB>2</SUB> and Cu/GO/MnO<SUB>2</SUB> nanocomposites by FT-IR, XRD, FESEM, TEM, HR-TEM, EDS, BET, TGA, VSM and elemental mapping. </LI> <LI> High recycling efficiency of the Cu/GO/MnO<SUB>2</SUB> nanocomposite in reduction reactions. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>