Low-grade heat harvesting by thermoelectric technology can contribute to efficient energy utilization. However, the large-scale application of thermoelectric devices is partially hindered by their unsatisfactory performance and relatively high cost. Here we prepared a cost-effective n-type Mg₃Bi₂-based compound with a peak zT of 1.24 at 573 K. A unicouple comprised of n-type Mg_3.2Bi_1.29Sb_0.7Te_0.01 and p-type Bi_0.2Sb_1.8Te₃ was constructed and its energy conversion efficiency was evaluated. The unicouple exhibited a record-high efficiency of (9.0 ± 0.5)% or (8.3 ± 0.4)% [considering the radiation heat loss] under a temperature difference of 265 K at the hot-side temperature of 573 K. Our results demonstrate the great potential of Mg₃Bi₂-based materials for low-grade heat recovery.

通过热电技术收集低等级的热量可以促进有效的能源利用。然而，热电装置的大规模应用由于其不令人满意的性能和相对较高的成本而受到部分阻碍。在这里，我们准备了具有成本效益的n型的Mg ₃的Bi ₂系化合物具有峰值的zT 1.24在573 K.甲unicouple由n型的Mg _3.2的Bi _1.29 Sb的_0.7碲_0.01且p型Bi _0.2 Sb的_1.8 Te ₃建造并评估其能量转换效率。在573 K的热侧温度下，在265 K的温差下，单电偶表现出创纪录的高效率（9.0±0.5）％或（8.3±0.4）％[考虑辐射热损失]。 Mg ₃ Bi ₂基材料在低品位热回收方面具有巨大潜力。