南京理工大学徐骉团队报道了在环保型单斜Cu₂S–四方Cu1.96S纳米热电结中实现zT>2。相关研究成果于2022年9月19日发表在《德国应用化学》。

由成分相同但相不同的纳米颗粒制成的相结纳米复合材料，为优化材料的物理化学性能提供了一个平台。

该文中，研究人员展示了与传统的剥离配体的方法不同的，通过保留表面1-十二硫醇（DDT）配体合成Cu₂-xS相结纳米复合材料的直接策略。结果，获得了常规单斜（m）相和非常规亚稳四方（t）相之间的相结。由于t相的掺杂，功率因数得到了显著提高。相结界面降低了热导率。最后，相结的表面调节将峰值zT推至932 K时的2.1，这是环境友好型金属硫化物的最高记录。

该项工作提供了通过表面配体调谐控制相结来优化热电性能的范例。

附：英文原文

Title: Realizing zT > 2 in Environment-Friendly Monoclinic Cu2S – Tetragonal Cu1.96S Nano-Phase Junctions for Thermoelectrics

Author: Xiaokun Li, Yue Lou, Kangpeng Jin, Liangwei Fu, Pengfei Xu, Zhan Shi, Tianli Feng, Biao Xu

Issue&Volume: 2022-09-19

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 Cu2-xS 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.

DOI: 10.1002/anie.202212885

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202212885