2018 - Sustainable Industrial Processing Summit & Exhibition
4-7 November 2018, Rio Othon Palace, Rio De Janeiro, Brazil
Seven Nobel Laureates have already confirmed their attendance: Prof. Dan Shechtman, Prof. Sir Fraser Stoddart, Prof. Andre Geim, Prof. Thomas Steitz, Prof. Ada Yonath, Prof. Kurt Wüthrich and Prof. Ferid Murad. More than 400 Abstracts Submitted from about 60 Countries.
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    Ab-initio Calculations of the Thermoelectric Properties of MXenes
    Udo Schwingenschlogl1;
    1KING ABDULLAH UNIVERSITY OF SCIENCE AND TECHNOLOGY (KAUST), Thuwal, Saudi Arabia;
    PAPER: 285/AdvancedMaterials/Keynote (Oral)
    SCHEDULED: 11:45/Wed./Guaratiba (60/2nd)



    ABSTRACT:
    This presentation gives an overview of ab-initio calculations [1-3] addressing the thermoelectric performance of MXenes. Specific examples include a comparison of Ti<sub>2</sub>CO<sub>2</sub>, Zr<sub>2</sub>CO<sub>2</sub>, and Hf<sub>2</sub>CO<sub>2</sub> in order to evaluate the role of the metal atom. The lattice thermal conductivity is demonstrated to grow along the series Ti-Zr-Hf in the temperature range 300-700 K, resulting in the highest figure of merit in the case of Ti<sub>2</sub>CO<sub>2</sub>. Flat conduction bands promote the thermopower in the case of n-doping. Functionalization effects are studied for Sc<sub>2</sub>C, which is semiconducting for various functional groups, including O, F, and OH. The lowest lattice thermal conductivity is found for OH functionalization. Therefore, despite a relatively low thermopower, Sc<sub>2</sub>C(OH)<sub>2</sub> may be interesting for intermediate-temperature thermoelectric applications due to a high electrical conductivity. We also discuss results on heterostructures built from MXenes and transition metal dichalcogenide monolayers. Low frequency optical phonons are found to occur as a consequence of the van der Waals bonding. They contribute significantly to thermal transport and compensate for reduced contributions of the acoustic phonons (strong scattering in heterostructures), such that the thermal conductivities become similar to those of the constituent MXenes.

    References:
    [1] A. N. Gandi, H. N. Alshareef, and U. Schwingenschlogl, Chem. Mater. 28 (2016), 1647-1652.
    [2] S. Kumar and U. Schwingenschlogl, Phys. Rev. B 94 (2016), 035405.
    [3] A. N. Gandi, H. N. Alshareef, and U. Schwingenschlogl, J. Phys.: Condens. Matter 29 (2017), 035504.