Preparation of MFI Nanosheets with Distinctive Microstructures via Facile Alkaline Etching

Although zeolite nanosheets (NSs) exhibit great prospects for a wide range of applications due to microstructural superiority, their facile preparation and microstructural tailoring remain a great challenge. In this study, uniform coffin-shaped MFI microcrystals were subjected to hydrothermal treatment in the presence of different types of alkaline etching agents, i.e., TMAOH, TEAOH, and TPAOH, for preparing MFI NSs with distinctive microstructures. It was found that the morphological and textural properties of MFI NSs could be readily tuned by varying etching agent types, etching agent contents, and hydrothermal treatment parameters, thereby leading to the formation of 10 nm thick leaf-shaped MFI NSs, ellipse-shaped MFI NSs, and single-crystal-like MFI NS aggregates through an in-plane oriented attachment. Simultaneously, the possible mechanisms involved in the formation of MFI NSs with distinctive microstructures were proposed. Among the prepared MFI NSs, 10 nm thick (ca. 5 unit cell) leaf-shaped MFI NSs represented one of the thinnest MFI NSs ever reported by the top-down method, while single-crystal-like MFI NS aggregates were prepared for the first time, which may endow them with superior performances in relevant application areas.