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Seamless lamination of a concave-convex architecture with single-layer graphene.
Park, Ji-Hoon,Lim, Taekyung,Baik, Jaeyoon,Seo, Keumyoung,Moon, Youngkwon,Park, Noejung,Shin, Hyun-Joon,Kyu Kwak, Sang,Ju, Sanghyun,Real Ahn, Joung RSC Pub 2015 Nanoscale Vol.7 No.43
<P>Graphene has been used as an electrode and channel material in electronic devices because of its superior physical properties. Recently, electronic devices have changed from a planar to a complicated three-dimensional (3D) geometry to overcome the limitations of planar devices. The evolution of electronic devices requires that graphene be adaptable to a 3D substrate. Here, we demonstrate that chemical-vapor-deposited single-layer graphene can be transferred onto a silicon dioxide substrate with a 3D geometry, such as a concave-convex architecture. A variety of silicon dioxide concave-convex architectures were uniformly and seamlessly laminated with graphene using a thermal treatment. The planar graphene was stretched to cover the concave-convex architecture, and the resulting strain on the curved graphene was spatially resolved by confocal Raman spectroscopy; molecular dynamic simulations were also conducted and supported the observations. Changes in electrical resistivity caused by the spatially varying strain induced as the graphene-silicon dioxide laminate varies dimensionally from 2D to 3D were measured by using a four-point probe. The resistivity measurements suggest that the electrical resistivity can be systematically controlled by the 3D geometry of the graphene-silicon dioxide laminate. This 3D graphene-insulator laminate will broaden the range of graphene applications beyond planar structures to 3D materials.</P>
Band gap sensitivity of bromine adsorption at carbon nanotubes
Park, Noejung,Miyamoto, Yoshiyuki,Lee, Kyuho,Ih Choi, Wooni,Ihm, Jisoon,Yu, Jaejun,Han, Seungwu Elsevier 2005 Chemical physics letters Vol.403 No.1
<P><B>Abstract</B></P><P>We report results of our first-principles investigation on the energetics and electronic structures of bromine-adsorbed carbon nanotubes. While the bromine molecule binds preferentially to the outer wall of metallic nanotubes, the binding energy of adsorbed atomic bromines are found to depend on the radius as well as the energy gap. A recent experiment on the nanotube separation using bromines is discussed based on our computational data. The formation of strong C–Br chemical bonds at the zigzag edge of graphite demonstrates a close relationship between the density of states at the Fermi level and the binding strength.</P>
Coordination Polymers for High-Capacity Li-Ion Batteries: Metal-Dependent Solid-State Reversibility
Lee, Hyun Ho,Lee, Jae Bin,Park, Yuwon,Park, Kern Ho,Okyay, Mahmut Sait,Shin, Dong-Seon,Kim, Sunghwan,Park, Jongnam,Park, Noejung,An, Byeong-Kwan,Jung, Yoon Seok,Lee, Hyun-Wook,Lee, Kyu Tae,Hong, Sung American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.26
<P>Electrode materials exploiting multielectron-transfer processes are essential components for large-scale energy storage systems. Organic-based electrode materials undergoing distinct molecular redox transformations can intrinsically circumvent the structural instability issue of conventional inorganic-based host materials associated with lattice volume expansion and pulverization. Yet, the fundamental mechanistic understanding of metal-organic coordination polymers toward the reversible electrochemical processes is still lacking. Herein, we demonstrate that metal-dependent spatial proximity and binding affinity play a critical role in the reversible redox processes, as verified by combined <SUP>13</SUP>C solid-state NMR, X-ray absorption spectroscopy, and transmission electron microscopy. During the electrochemical lithiation, in situ generated metallic nanoparticles dispersed in the organic matrix generate electrically conductive paths, synergistically aiding subsequent multielectron transfer to π-conjugated ligands. Comprehensive screening on 3d-metal-organic coordination polymers leads to a high-capacity electrode material, cobalt-2,5-thiophenedicarboxylate, which delivers a stable specific capacity of ∼1100 mA h g<SUP>-1</SUP> after 100 cycles.</P> [FIG OMISSION]</BR>