Thermally stable inorganic Bi0.4Sb1.6Te3/metal–organic framework (MOF) composites with 1-by-1 nm pore engineering towards mid-temperature thermoelectrics

Abstract

Metal–organic frameworks (MOFs) exhibit substantial promise in the field of thermoelectrics, thanks to their adjustable porosity and modifiable physical/chemical characteristics. The widespread application of MOFs in thermoelectricity has been hampered by their low conductivity and limited thermal stability. In this work, a uniform dispersion of MOFs within the Bi_0.4Sb_1.6Te₃ matrix is realized. This results in dual benefits: the assurance of microstructural stability of MOFs within the composites and a significant enhancement in electrical transport of Bi_0.4Sb_1.6Te₃ induced by the organic–inorganic interfacial electron transfer. Meanwhile, the 1-by-1-nm-tuned pores and intricate hierarchical architecture of MOFs play crucial roles in diminishing the thermal conductivity of Bi_0.4Sb_1.6Te₃. Consequently, the notable thermoelectric performance of the Bi_0.4Sb_1.6Te₃/0.5 wt% ZIF-8 nanocomposite is achieved, including a peak zT of 1.65 at 348 K, a remarkable maximum cooling ΔT of 71.6 K at T_h = 300 K, and a record-high thermoelectric conversion efficiency of 6.7% at ΔT = 238 K. This study utilizes the unique structural features of MOFs, broadening their applications into the mid-temperature range within the field of thermoelectrics.