In Situ Coupling of MHz Acoustic Waves for the Synthesis of Hierarchical UiO-66 Metal-Organic Frameworks.

Engineering the physical properties of metal-organic frameworks (MOFs) to improve their performance has been a key focus area for establishing their use in a variety of applications. While some synthesis strategies have shown promise in this regard, a method that can simultaneously give rise to unique properties in the MOF structure across multiple dimensions (e.g., the nano-, meso-, and macro-scales), which can be critical for a number of practical applications, has never been reported. Herein, we report an acoustomicrofluidic platform that concurrently facilitates such multiscale manipulation of the MOFs' physical properties. In just several minutes at room temperature, large (O(10-100 μm)) monolithic superstructures of UiO-66 MOFs (a MOF model with excellent stability) can be synthesized with highly desirable properties. These properties include hierarchical (micro- and meso-scale) porosity and nanoscale framework-level defects, all of which are absent in conventional-prepared UiO-66 with solvothermal synthesis. We show (as examples of the benefits of simultaneously enhancing the MOF properties on multiple dimensional levels) their practical application for simultaneous capture and degradation of large dye molecules, and for UV photodetection with superior responsivity.