Browsing by Author "Wang, Tuo"

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    Energy Applications of Graphene-Based Nanomaterials and Their Composites
    (2018-11-26) Wang, Tuo; Tour, James M
    Graphene-based nanomaterials, which contain two-dimensional graphene sheets that consist of sp2-C atoms arranged in a hexagonal lattice, have exceptional electrical conductivity and mechanical properties, thereby showing promise for use in energy-related devices. Two different types of graphene nanomaterials were studied: one-dimensional graphene nanoribbons and three-dimensional graphene foams. The graphene nanoribbons have both abundant edges for chemical functionalization that improves their dispersibility and interfacial interaction with other materials, and high aspect ratio that affords percolation on a specific area at a smaller mass loading. They have been demonstrated to be an excellent choice for making conductive films with deicing and anti-icing capabilities (Chapter 1) and as a conductive additive for dendrite-free Li metal anodes in Li metal batteries and red P anodes in high energy density Li-ion batteries (Chapter 2). It was found that red P was not only a good candidate for anode materials, but a surprisingly powerful tool to improve battery safety by in situ detection of Li dendrites in an ordinary two-electrode battery system. The other graphene nanomaterial, the three-dimensional graphene foams prepared from polyacrylonitrile using the powder metallurgy method, exhibited high electrical conductivity and high mechanical strength that powdered graphene species cannot achieve, which enabled them to reinforce epoxy resin and enhance the electrical conductivity of the epoxy to an unprecedented level (Chapter 3).
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    High Performance Electrocatalytic Reaction of Hydrogen and Oxygen on Ruthenium Nanoclusters
    (American Chemical Society, 2017) Ye, Ruquan; Liu, Yuanyue; Peng, Zhiwei; Wang, Tuo; Jalilov, Almaz S.; Yakobson, Boris I.; Wei, Su-Huai; Tour, James M.; Smalley Institute for Nanoscale Science and Technology
    The development of catalytic materials for the hydrogen oxidation, hydrogen evolution, oxygen reduction or oxygen evolution reactions with high reaction rates and low overpotentials are key goals for the development of renewable energy. We report here Ru(0) nanoclusters supported on nitrogen-doped graphene as high-performance multifunctional catalysts for the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR), showing activities similar to that of commercial Pt/C in alkaline solution. For HER performance in alkaline media, sample Ru/NG-750 reaches 10 mA cm–2 at an overpotential of 8 mV with a Tafel slope of 30 mV dec–1. The high HER performance in alkaline solution is advantageous because most catalysts for ORR and oxygen evolution reaction (OER) also prefer alkaline solution environment whereas degrade in acidic electrolytes. For ORR performance, Ru/NG effectively catalyzes the conversion of O2 into OH– via a 4e process at a current density comparable to that of Pt/C. The unusual catalytic activities of Ru(0) nanoclusters reported here are important discoveries for the advancement of renewable energy conversion reactions.
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    High-Performance Hydrogen Evolution from MoS2(1–x)P x Solid Solution
    (Wiley, 2016) Ye, Ruquan; Vicente, Paz Del Angel; Liu, Yuanyue; Arellano-Jimenez, Josefina; Peng, Zhiwei; Wang, Tuo; Li, Yilun; Yakobson, Boris I.; Wei, Su-Huai; Yacaman, Miguel Jose; Tour, James M.; Smalley Institute for Nanoscale Science and Technology
    A MoS2(1-x)Px solid solution (x = 0 to 1) is formed by thermally annealing mixtures of MoS2 and red phosphorus. The effective and stable electrocatalyst for hydrogen evolution in acidic solution holds promise for replacing scarce and expensive platinum that is used in present catalyst systems. The high performance originates from the increased surface area and roughness of the solid solution.
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    Physical and electrical characterization of TexasPEG: An electrically conductive neuronal scaffold
    (Wolters Kluwer - Medknow, 2017) Sikkema, William K.A.; Metzger, Andrew B.; Wang, Tuo; Tour, James M.
    Background: Graphene and its derivatives have been shown to be biocompatible and electrically active materials upon which neurons readily grow. The fusogen poly(ethylene glycol) (PEG) has been shown to improve outcomes after cervical and dorsal spinal cord transection. The long and narrow PEGylated graphene nanoribbon stacks (PEG-GNRs) with their 5 μm × 200 nm × 10 nm dimensions can provide a scaffold upon which neurons can grow and fuse. We disclose here the extensive characterization data for the PEG-GNRs. Methods: PEG-GNRs were chemically synthesized and chemically and electrically characterized. Results: The average aspect ratio of the PEG-GNRs was determined to be ~85, which corresponds to a critical percolation value (the point where insulating material becomes conductive by addition of conductive particles) of 1%. However, there was not a sharp increase in AC conductivity at frequencies relevant to action potentials. Conclusion: A robust characterization of PEG-GNRs is discussed, though the precise origin of efficacy in improving outcomes following spinal cord transection is not known.