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BORON NANOWIRES AND NOVEL TUBE–CATALYTIC PARTICLE–WIRE HYBRID BORON NANOSTRUCTURES
RODNEY S. RUOFF,TERRY T. XU,ALAN W. NICHOLLS 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2006 NANO Vol.1 No.1
Catalyst-assisted growth of boron nanowires and novel tube–catalytic particle–wire hybrid boron nanostructures were achieved by pyrolysis of diborane at 820–890°C and ~ 200 mTorr in a quartz tube furnace. Electron microscopy imaging and diffraction analysis reveal that most of the nano-structures are amorphous. Elemental analysis by EELS and EDX shows that the nanostructures consist of boron with a small amount of oxygen and carbon. Possible growth mechanisms for the tube–catalytic particle–wire hybrid boron nanostructures are discussed.
First-principles investigation of wet-chemical routes for the hydrogenation of graphene
Horbatenko, Yevhen,Choi, Min,Ruoff, Rodney S.,Bielawski, Christopher W.,Park, Noejung Elsevier 2015 Carbon Vol.93 No.-
<P><B>Abstract</B></P> <P>To investigate the microscopic mechanism for the wet-chemical hydrogenation of graphene, first principles density functional calculations were performed for the hydrogen transfer reaction between the graphene surface and a mixture of hydrogen carrier and electron donor. For the hydrogen transfer from CH<SUB>3</SUB>OH to graphene, as commonly used in Birch-type reductions, the presence of alkali atoms is important not only because they donate electrons but also stabilize the CH<SUB>3</SUB>O<SUP>−</SUP>. On the other hand, when a hydrogen carrier becomes charge neutral after the transfer, as for the case of CH<SUB>3</SUB>NH<SUB>3</SUB> <SUP>+</SUP>, the presence of alkali atoms is not essential, and the supply of electrons from an external source can lead to as favorable thermodynamics as that of alkali atoms. We suggest that, based on these results, a potentially more efficient experimental procedure can be designed.</P>
Simultaneous Electrochemical Reduction and Delamination of Graphene Oxide Films
Wang, Xiaohan,Kholmanov, Iskandar,Chou, Harry,Ruoff, Rodney S. American Chemical Society 2015 ACS NANO Vol.9 No.9
<P>Here we report an electrochemical method to simultaneously reduce and delaminate graphene oxide (G-O) thin films deposited on metal (Al and Au) substrates. During the electrochemical reaction, interface charge transfer between the G-O thin film and the electrode surface was found to be important in eliminating oxygen-containing groups, yielding highly reduced graphene oxide (rG-O). In the meantime, hydrogen bubbles were electrochemically generated at the rG-O film/electrode interface, propagating the film delamination. Unlike other metal-based G-O reduction methods, the metal used here was either not etched at all (for Au) or etched a small amount (for Al), thus making it possible to reuse the substrate and lower production costs. The delaminated rG-O film exhibits a thickness-dependent degree of reduction: greater reduction is achieved in thinner films. The thin rG-O films having an optical transmittance of 90% (λ = 550 nm) had a sheet resistance of 6390 ± 447 Ω/□ (ohms per square). rG-O-based stretchable transparent conducting films were also demonstrated.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2015/ancac3.2015.9.issue-9/acsnano.5b03814/production/images/medium/nn-2015-03814x_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn5b03814'>ACS Electronic Supporting Info</A></P>
Search for arc-produced heterofullerenes
Lamb, John R.,Kwon, Youngwoo,Ruoff, Rodney S.,Lamb, Lowell D. Elsevier 2017 Carbon Vol.119 No.-
<P>Replacing one or more of the carbon atoms in a fullerene cage with one or more non-carbon atoms is expected to result in a structure (heterofullerene) with significantly altered and potentially useful properties. While (C59N)- and (C69N)-based compounds can be synthesized via solution-phase modification of C-60 and C-70, respectively, a general, high-yield method for producing heterofullerenes has not been identified. We report the results of a search for heterofullerenes using atmospheric pressure photo-ionization mass spectrometry on samples of fullerene soot produced in nitrogen and carbon monoxide via the Kratschmer-Huffman arc technique. Contrary to earlier reports, we found no evidence of the presence of heterofullerenes in any of the samples we examined. X-ray photoelectron spectroscopy of fullerene soot produced in nitrogen indicates that while nitrogen is incorporated into the carbon matrix, the observed nitrogen-carbon bonding configurations do not permit the formation of fullerenes. We also report the discovery of production conditions under which argon can be used as a buffer gas and the yield of soluble fullerenes is comparable to the best yield achievable using helium. These findings may shed light on the general problem of the fullerene formation process. (C) 2017 Elsevier Ltd. All rights reserved.</P>
Ultra Long-Range Interactions between Large Area Graphene and Silicon
Na, Seung Ryul,Suk, Ji Won,Ruoff, Rodney S.,Huang, Rui,Liechti, Kenneth M. American Chemical Society 2014 ACS NANO Vol.8 No.11
<P>The wet-transfer of graphene grown by chemical vapor deposition (CVD) has been the standard procedure for transferring graphene to any substrate. However, the nature of the interactions between large area graphene and target substrates is unknown. Here, we report on measurements of the traction–separation relations, which represent the strength and range of adhesive interactions, and the adhesion energy between wet-transferred, CVD grown graphene and the native oxide surface of silicon substrates. These were determined by coupling interferometry measurements of the separation between the graphene and silicon with fracture mechanics concepts and analyses. The measured adhesion energy was 357 ± 16 mJ/m<SUP>2</SUP>, which is commensurate with van der Waals interactions. However, the deduced traction–separation relation for graphene-silicon interactions exhibited a much longer range interaction than those normally associated with van der Waals forces, suggesting that other mechanisms are present.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2014/ancac3.2014.8.issue-11/nn503624f/production/images/medium/nn-2014-03624f_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn503624f'>ACS Electronic Supporting Info</A></P>