Ultrafast Synthesis of Ultrathin Two-Dimensional Metal–Organic Framework Nanosheets with High Space-Time Yield

The rapid synthesis of two-dimensional metal organic framework (2DMOF) materials with high space-time yield (STY) is a prerequisite for its practical application, but it is very challenging. The present work addresses this issue by systematically investigating the synthetic conditions of a microwave-assisted method to develop an ultrafast bottom-up method for synthesizing stable 2DMOF materials. This method is applied to produce a very stable Hf-BTB 2DMOF composed of six-connected Hf6O4(OH)412+ clusters and the tritopic carboxylate ligand 1,3,5-tris(4-carboxyphenyl)benzene (BTB). The process is demonstrated to yield exclusively pure phase Hf-BTB 2DMOFs in as little time as 2 min. Its production rate and space-time yield exceed 3.8 g h–1 and 2870 kg m–3 day–1, which are the highest values reported to date. The effects of heating-up time, holding time, modulator, and solvent were systematically investigated, and it was found that the exclusive production of pure-phase 2DMOF nanosheets comprising up to only a few layers can be obtained without critical control of these synthetic conditions. The method also has a certain universality for the preparation of 2D coordination materials formed by other metals (Zr) and three-connected linkers. These characteristics make our method conducive to scale-up and industrial production.