Issue 35, 2023

Graphene-assisted synergistic electronic DOS modulation and phonon scattering to improve the thermoelectric performance of Mg3Sb2-based materials

Abstract

Grain boundary (GB) scattering has been widely reckoned as a primary restraint on room-temperature (RT) carrier mobility in Mg3Sb2-based materials. In this work, two-dimensional graphene (G) with varied contents was added to single phase Mg3.24Sb1.5Bi0.49Te0.01 materials in order to tailor the highly resistive space-charge region at GBs. The results indicate that introducing G effectively lowers the carrier transport energy barrier Eb from 42 meV (pristine sample) to 18 meV (Mg3.24Sb1.5Bi0.49Te0.01/1.0 vol% G sample), and correspondingly increases the drift mobility by 112.5% from 32 cm2 V−1 s−1 to 68 cm2 V−1 s−1 at RT, leading to an enhanced power factor and thus ZT value. Besides, first-principles calculations were also performed to qualitatively bridge the underlying negative correlation between the electronic density of states (DOS) and GB potential barrier Eb. Moreover, the equivalent nano-particle phonon scattering is also realized through introducing the two-dimensional G, contributing to a moderate reduction in lattice thermal conductivity as quantitatively illustrated based on the Debye–Callaway model. Consequently, the figure of merit ZT for G-added samples is greatly improved in the entire temperature range compared with that of the G-free sample. This study opens up a new avenue for rationally engineering the grain boundary, via regulating interfacial electronic DOS, to optimize electrical transport properties and ZT values.

Graphical abstract: Graphene-assisted synergistic electronic DOS modulation and phonon scattering to improve the thermoelectric performance of Mg3Sb2-based materials

Supplementary files

Article information

Article type
Paper
Submitted
24 Apr 2023
Accepted
09 Aug 2023
First published
10 Aug 2023

J. Mater. Chem. A, 2023,11, 18811-18819

Graphene-assisted synergistic electronic DOS modulation and phonon scattering to improve the thermoelectric performance of Mg3Sb2-based materials

Q. Zhang, J. Li, N. S. Chauhan, L. Wang, Z. Huang, W. Fan, K. Hayashi, S. Chen, J. Fan and Y. Miyazaki, J. Mater. Chem. A, 2023, 11, 18811 DOI: 10.1039/D3TA02431H

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