Browsing by Author "Xiang, Changsheng"

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    Carbon Nanomaterials for Fibers, Photonics and Composites
    (2014-04-21) Xiang, Changsheng; Tour, James M.; Pasquali, Matteo; Marti, Angel A.
    This thesis investigates various carbon nanomaterials from the basic synthesis to the characterizations and applications in fibers, photonics and composites. The carbon nanomaterials we studied include graphene, graphene oxide, graphene nanoribbons, functionalized graphene nanoribbons, graphene oxide nanoribbons, graphene quantum dots and carbon nanotubes. With all these chemical approaches, these carbon nanomaterials’ mechanical, electrical, photonic and gas barrier properties were carefully studied and demonstrated.
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    Methods of producing graphene quantum dots from coal and coke
    (2018-03-20) Tour, James M.; Ye, Ruquan; Xiang, Changsheng; Lin, Jian; Peng, Zhiwei; Ceriotti, Gabriel; Rice University; United States Patent and Trademark Office
    In some embodiments, the present disclosure pertains to methods of making graphene quantum dots from a carbon source (e.g., coal, coke, and combinations thereof) by exposing the carbon source to an oxidant. In some embodiments, the methods of the present disclosure further comprise a step of separating the formed graphene quantum dots from the oxidant. In some embodiments, the methods of the present disclosure further comprise a step of reducing the formed graphene quantum dots. In some embodiments, the methods of the present disclosure further comprise a step of enhancing a quantum yield of the graphene quantum dots. In further embodiments, the methods of the present disclosure also include a step of controlling the diameter of the formed graphene quantum dots by selecting the carbon source. In some embodiments, the formed graphene quantum dots comprise oxygen addends or amorphous carbon addends on their edges.
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    Rebar Graphene
    (American Chemical Society, 2014) Yan, Zheng; Peng, Zhiwei; Casillas, Gilberto; Lin, Jian; Xiang, Changsheng; Zhou, Haiqing; Yang, Yang; Ruan, Gedeng; Raji, Abdul-Rahman O.; Samuel, Errol L.G.; Hauge, Robert H.; Yacaman, Miguel Jose; Tour, James M.; Richard E. Smalley Institute for Nanoscale Science and Technology
    As the cylindrical sp2-bonded carbon allotrope, carbon nanotubes (CNTs) have been widely used to reinforce bulk materials such as polymers, ceramics, and metals. However, both the concept demonstration and the fundamental understanding on how 1D CNTs reinforce atomically thin 2D layered materials, such as graphene, are still absent. Here, we demonstrate the successful synthesis of CNT-toughened graphene by simply annealing functionalized CNTs on Cu foils without needing to introduce extraneous carbon sources. The CNTs act as reinforcing bar (rebar), toughening the graphene through both π–π stacking domains and covalent bonding where the CNTs partially unzip and form a seamless 2D conjoined hybrid as revealed by aberration-corrected scanning transmission electron microscopy analysis. This is termed rebar graphene. Rebar graphene can be free-standing on water and transferred onto target substrates without needing a polymer-coating due to the rebar effects of the CNTs. The utility of rebar graphene sheets as flexible all-carbon transparent electrodes is demonstrated. The in-plane marriage of 1D nanotubes and 2D layered materials might herald an electrical and mechanical union that extends beyond carbon chemistry.