Browsing by Author "Nam, Jae-Do"

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    Composite Membrane Based on Graphene Oxide Sheets and Nafion for Polymer Electrolyte Membrane Fuel Cells
    (Electrochemical Society, 2014-10-29) Wang, Liang; Kang, Junmo; Nam, Jae-Do; Suhr, Jonghwan; Prasad, Ajay K.; Advani, Suresh G.; Liang Wang, Junmo Kang, Jae-Do Nam, Jonghwan Suhr, Ajay K. Prasad and Suresh G. Advani; Wang, Liang; Prasad, Ajay K.; Advani, Suresh G.
    A composite membrane for fuel cell applications was prepared by incorporating custom-made graphene oxide (GO) in Nafion resin. The GO was used to provide mechanical reinforcement to Nafion. Transmission electron microscopy confirmed the formation of highly crystalline and individually-dispersed graphene oxide sheets. Tensile strength, water uptake, swelling, proton conductivity and electrical conductivity of the composite membranes were measured and compared with pure Nafion. The polarization curves indicated that the fuel cell performance of the 3wt% GO/Nafion composite membrane was similar to that of the pure Nafion membrane, but the composite membrane was superior to Nafion in terms of mechanical properties.
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    Understanding the nanoscale local buckling behavior of vertically aligned MWCNT arrays with van der Waals interactions
    (Royal Society of Chemistry, 2015-07-20) Li, Yupeng; Kim, Hyung-ick; Wei, Bingqing; Kang, Junmo; Choi, Jae-boong; Nam, Jae-Do; Suhr, Jonghwan; Yupeng Li, Hyung-ick Kim, Bingqing Wei, Junmo Kang, Jae-boong Choi, Jae-Do Nam and Jonghwan Suhr; Li, Yupeng; Wei, Bingqing
    The local buckling behavior of vertically aligned carbon nanotubes (VACNTs) has been investigated and interpreted in the view of a collective nanotube response by taking van der Waals interactions into account. To the best of our knowledge, this is the first report on the case of collective VACNT behavior regarding van der Waals force among nanotubes as a lateral support effect during the buckling process. The local buckling propagation and development of VACNTs were experimentally observed and theoretically analyzed by employing finite element modeling with lateral support from van der Waals interactions among nanotubes. Both experimental and theoretical analyses show that VACNTs buckled in the bottom region with many short waves and almost identical wavelengths, indicating a high mode buckling. Furthermore, the propagation and development mechanism of buckling waves follow the wave damping effect.