• Graphene gets enhanced by flashing

    From ScienceDaily@1:317/3 to All on Thu Mar 31 22:30:46 2022
    Graphene gets enhanced by flashing
    Process customizes one-, two- or three-element doping for applications


    Date:
    March 31, 2022
    Source:
    Rice University
    Summary:
    Scientists who developed the flash Joule heating process to make
    graphene have found a way to produce doped graphene to customize
    it for applications.



    FULL STORY ========================================================================== Flashing graphene into existence from waste was merely a good start. Now
    Rice University researchers are customizing it.


    ==========================================================================
    The Rice lab of chemist James Tour has modified its flash Joule heating
    process to produce doped graphene that tailors the atom-thick material's structures and electronic states to make them more suitable for optical
    and electronic nanodevices. The doping process adds other elements to graphene's 2D carbon matrix.

    The process reported in the American Chemical Society journal ACS
    Nano shows how graphene can be doped with a single element or with
    pairs or trios of elements. The process was demonstrated with single
    elements boron, nitrogen, oxygen, phosphorus and sulfur, a two-element combination of boron and nitrogen, and a three-element mix of boron,
    nitrogen and sulfur.

    The process takes about one second, is both catalyst- and solvent-free,
    and is entirely dependent on "flashing" a powder that combines the dopant elements with carbon black.

    Doping graphene is possible through bottom-up approaches like chemical
    vapor deposition or synthetic organic processes, but these usually
    yield products in trace amounts or produce defects in the graphene. The
    Rice process is a promising route to produce large quantities of "heteroatom-doped" graphene quickly and without solvents, catalysts
    or water.

    "This opens up a new realm of possibilities for flash graphene,"
    Tour said.

    "Once we learned to make the original product, we knew the ability
    to directly synthesize doped turbostratic graphene would lead to many
    more options for useful products. These new atoms added to the graphene
    matrix will permit stronger composites to be made since the new atoms
    will bind better to the host material, such as concrete, asphalt or
    plastic. The added atoms will also modify the electronic properties,
    making them better-suited for specific electronic and optical devices." Graphene is turbostratic when stacks of the 2D honeycomblike lattices
    don't align with one another. This makes it easier to disperse the
    nanoscale sheets in a solution, producing soluble graphene that is much
    simpler to incorporate into other materials, Tour said.

    The lab tested various doped graphenes in two scenarios: electrochemical
    oxygen reduction reactions (ORR) that are key to catalytic devices
    like fuel cells, and as part of an electrode in lithium metal batteries
    that represent the next generation of rechargeable batteries with high
    energy densities.

    Sulfur-doped graphene proved best for ORR, while nitrogen-doped
    graphene proved able to reduce nucleation overpotential during the electrodeposition of metallic lithium. That should facilitate more uniform deposition and improved stability in next-generation rechargeable metal batteries, the lab reported.

    Rice graduate students Weiyin Chen and Chang Ge are co-lead authors
    of the paper. Co-authors are alumnus John Tianci Li, graduate students
    Jacob Beckham, Kevin Wyss, Paul Advincula, Lucas Eddy and Jinhang Chen, undergraduate Robert Carter, postdoctoral researcher Zhe Yuan, research scientist Carter Kittrell and alumnus Duy Xuan Luong.

    The research was supported by the Air Force Office of Scientific Research (FA9550-19-1-0296), the Department of Energy-National Energy Technology Laboratory (DE-FE0031794) and the U.S. Army Corps of Engineers' Engineer Research and Development Center (W912HZ-21-2-0050).


    ========================================================================== Story Source: Materials provided by Rice_University. Original written
    by Mike Williams. Note: Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Weiyin Chen, Chang Ge, John Tianci Li, Jacob L. Beckham, Zhe
    Yuan, Kevin
    M. Wyss, Paul A. Advincula, Lucas Eddy, Carter Kittrell,
    Jinhang Chen, Duy Xuan Luong, Robert A. Carter, James
    M. Tour. Heteroatom-Doped Flash Graphene. ACS Nano, 2022; DOI:
    10.1021/acsnano.2c01136 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/03/220331151538.htm

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