Cu²O mediated synthesis of metal-organic framework UiO-66 in nanometer scale

Controlled synthesis of metal-organic frameworks (MOFs) in nanometer scale is highly desired for the optimization of properties and the extending of applications. In this work, Cu₂O was used as additive for the first time in the synthesis of zirconium-based MOF UiO-66. We found that the amount of Cu₂O additive had an important impact on downsizing the crystal size of UiO-66. Cu2O additive plays a role of rate controller of crystal growth of UiO-66 crystals by their competitive coordination behavior with the linker H₂BDC between the [Zr-O] clusters. This generates a depleted H2BDC concentration for the coordination with the [Zr-O] clusters for constructing the UiO-66 framework, which favors the production of small crystals. As a result, well-dispersed nanometer scale UiO-66 crystals with mean crystal size of 40 nm can be easily synthesized by the addition of Cu₂O. The as-synthesized nanometer scale UiO-66 crystals have a pure crystal structure with high crystallinity and superior porosity.