Template-assisted, seed-mediated synthesis of hierarchically mesoporous core-shell UiO-66: enhancing adsorption capacity and catalytic activity through iterative growth

A hierarchically mesoporous (HM) UiO-66-F-4 shell with similar to 8 nm mesopores can be iteratively grown on top of UiO-66 nanoparticle (NP) seeds over several cycles templated by Pluronic F-127 micelles. Presumably, the Pluronic micelles that were formed in water can surround UiO-66 NPs to facilitate the overgrowth of an HM-UiO-66-F-4 shell in the presence of Zr-IV precursors and BDC-F-4 linkers. The UiO-66 NP seeds play an important role in directing the continuous growth of the HM-UiO-66-F-4 shell, as only a nonporous phase was obtained in their absence. This template-assisted, seed-mediated method can be extended to produce other UiO-66-X (X = (OH)(2), (COOH)(2), etc.) shells, demonstrating its generality for the UiO-66 family of metal-organic frameworks. Notably, the incorporation of mesopores into the thrice-overgrown UiO-66@HM vertical bar(3rd)-UiO-66-F-4 materials leads to impressive enhancements in the per-mass uptake capacity of Direct Blue 86, a large anionic dye: 320% better than the parent UiO-66 seeds and 150% better than that for a [UiO-66 + UiO-66-F-4] physical mixture at the same mass proportion. Similar enhancements were also observed in the catalyzed oxidation of thioanisole.