Tailored Design of Hierarchically Porous UiO-66 with a Controlled Pore Structure and Metal Sites

Hierarchically porous metal-organic frameworks (MOFs) not only inherit the merits of MOFs such as high porosity, but they also possess distinct properties such as a broader pore size range and thus more rapid mass transport. Simple, controllable synthesis of hollow or mesoporous structures with tailored pore features and more metal sites is desired and remains challenging. Herein, we demonstrate a facile strategy for fabricating hollow/mesoporous UiO-66 through a designed defect density and subsequent etching process. The strategy relies on the construction of an inhomogeneous nanoarchitecture in which the addition of water in UiO-66 synthesis can facilitate the formation of linker defects by promoting the explosive nucleation of UiO-66 and acetic acid deprotonation, and the more defective core will be selectively etched by sodium hydroxide. The morphology, size, pore structure, and metal sites can be exquisitely designed by rationally adjusting the water dosage and etching conditions. Markedly, UiO-66 with larger mesopores contributes to excellent glyphosate adsorption capacity, and the hollow UiO-66 catalyst with more active metal sites exhibits superior performance in the [3 + 3] cycloaddition reaction.