A Non-Equilibrium Flame Aerosol Process to Create High-Entropy MOFs.

Abstract

High-entropy alloys and ceramics have demonstrated promising applications in the past decade. Ultrafast heating and cooling can kinetically trap immiscible elements into solid solutions, expanding the compositional space and optimizing the properties of high-entropy materials. However, the extreme temperatures required by these non-equilibrium methods are incompatible with metal-organic frameworks (MOFs). This work presents a flame aerosol strategy for synthesizing compositionally complex, entropically stabilized MOFs, enabling new combinations of properties previously inaccessible in this class of materials. Using the HKUST structure as a prototype, this methodology is extended to a wide array of both crystalline and amorphous MOFs, and then to a 10-element MOF that incorporates transition metals, rare-earth metals, alkaline-earth metals, p-block metals, and noble metals. This strategy can be further applied to inorganic coordination polymers. This study reveals that kinetics and entropy collectively drive structural short-range periodicity and configurational disorder in the framework, which in turn influence crystallinity, pore architecture, defect density, homogeneity, and electrochemical properties. This work expands the compositional design space for MOFs and offers new opportunities for their fundamental study and practical application.