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

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.