Stabilizing sub-nanoporous zinc metal–organic frameworks in SnTe thermoelectrics for high-temperature power generation

Abstract

The integration of porous metal–organic frameworks (MOFs) with thermoelectric materials offers an effective route toward the phonon-glass electron crystal paradigm. However, their application in high-temperature power generation remains severely limited by the intrinsic thermal instability of MOFs arising from weak coordination bonding. Here, we report a thermally robust heterostructure that is stable from 300 to 873 K, achieved by embedding sub-nanoporous Zn-[2-methylimidazolate] frameworks (ZIF-8) into Sn-rich SnTe nanomaterials synthesized by a base-amine-mediated solvothermal method. We reveal that the remarkably low solubility of Zn in SnTe inhibits Zn diffusion, thereby stabilizing the Zn nodes and preserving the Zn–N coordination network at elevated temperatures. The SnTe/ZIF-8 nanocomposite introduces an interface-induced energy filtering effect for electrical optimization. Simultaneously, the porosity-induced thermal radiation, the hierarchical defects, and the interfacial Kapitza resistance enable strong phonon scattering across a broad frequency spectrum. As a result, a maximum zT value of 1.3 at 873 K is achieved, among the highest values reported for heterostructure-enhanced SnTe thermoelectric materials without lattice doping. This work provides essential design principles for thermally stable MOF-based heterostructures and extends their applicability to high-temperature (>773 K) thermoelectric power generation.