Nanoscale Control of Homoepitaxial Growth on a Two-Dimensional Zeolite

Zeolites, crystalline microporous solids are of interest for a variety of applications including catalysis, adsorption, ion-exchange, separation membranes etc. Advances in the understanding of zeolite synthesis and crystallization have facilitated the development of core-shell catalysts, hierarchical materials, exfoliated two-dimensional nanosheets and thin films. Thus control of zeolite growth at a scale approaching single-unit-cell dimension is important to tailor their microstructure for performance optimization. However growth studies focusing on nanoscale control are still in their infancy.

In this work, we report on solution-based growth conditions that lead to slow and controllable epitaxial growth of two-dimensional MFI zeolite nanosheets. Growth rates on the order of few nanometers per day were achieved. Anisotropic growth in the absence of misoriented domains was facilitated by use of an organic additive which suppresses the non-classical crystal growth pathway predominant in most zeolites to favor a classical pathway involving growth by addition of molecular silica species.