Abstract
The synthesis of ultra-thin BPH zeolite nanosheets from an aluminosilicate colloidal suspension using exclusively inorganic structure directing agents under mild conditions is reported. The improved synthesis yields nanosheets of 4-7 nm and a Si/Al ratio of 1.5; combined 3D electron diffraction and DFT calculations reveal the spatial distribution of extra-framework cations throughout the microporous structure. The ultra-thin BPH nanosheets exhibit high and regular inter-sheet mesoporosity, and substantially improved thermal stability. The notable mesoporosity bestows exceptional water adsorption behavior typically unseen for zeolites; the as-prepared material consists of up to 49% adsorbed H2O by weight, and adsorbs up to 32 wt% H2O at 90% relative humidity. 2 H MAS NMR spectroscopy identifies different types of O 2 H environments ascribed to silanol species exhibiting two motion behaviors. H2O sorption analysis demonstrates reproducible behavior over multiple cycles and low temperature regeneration, making the ultra-thin BPH nanosheets attractive candidates for gas drying and membrane applications.