Realizing zT>2 in Environment-Friendly Monoclinic Cu 2 S-Tetragonal Cu 1.96 S Nano-Phase Junctions for Thermoelectrics.

Authors :: Li X
Lou Y
Jin K
Fu L
Xu P
Shi Z
Feng T
Xu B
Source :: Angewandte Chemie (International ed. in English) [Angew Chem Int Ed Engl] 2022 Nov 07; Vol. 61 (45), pp. e202212885. Date of Electronic Publication: 2022 Oct 07.
Publication Year :: 2022
Abstract: Phase-junction nanocomposites, made of nanograins with the same composition but different phases, offer a platform to optimize the physiochemical performance of materials. Herein, we demonstrate a straightforward strategy to synthesize Cu <subscript>2-x</subscript> S phase-junction nanocomposites by retaining surface 1-dodecanethiol (DDT) ligands, in contrast to the traditional method that strips the ligands. As a result, phase junctions between a conventional monoclinic (m) phase and an unconventional metastable tetragonal (t) phase are obtained. The significantly improved power factor is obtained due to the doping of the t-phase. The phase-junction interfaces reduce thermal conductivity. Finally, surface regulation of phase junctions pushes the peak zT to 2.1 at 932 K, being the highest reported for environment-friendly metal sulfides. This work provides a paradigm to optimize thermoelectric performance by controlling phase junctions through surface-ligand tuning.<br /> (© 2022 Wiley-VCH GmbH.)

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