Atomically thin, large area aluminosilicate nanosheets fabricated from layered clay minerals

Abstract

Two-dimensional (2-D) nanosheets, which have dimensions of atomically thin thickness with extremely high aspect ratio, have gathered great attentions due to their interesting properties and potential applications. Especially, some ceramic nanosheets including borides, carbides and sulfides became epitomes of novel functional nanomaterials since they exhibited unique electrical and surface properties distinguished from their bulk forms. In this study, atomically thin nanosheets of aluminosilicate oxides were fabricated via exfoliation of layered clay mineral, mica (muscovite; KAl3Si3O10(OH)(2)). To overcome the difficulties in exfoliations of large area nanosheets from mica, which has relatively strong interlayer bonding originated from layer charge, polymer assisted wet chemical method were applied. Amphiphilic polymer molecules were successfully intercalated into the ion exchanged muscovite particles to separate each layer. The resulting product possesses nanosheets with micrometer scale lateral sizes. The measured thicknesses of the nanosheets were mainly fell in two groups (1.2-1.7 rim and 2.2-2.7 nm) which correspond to the mono- and di-layer thicknesses of the muscovite with polymer adsorbates, respectively. The FT-IR and Raman results indicated that the adsorption of polymer molecules on the both surfaces of the aluminosilicate nanosheets significantly weaken or even break the interlayer bonding. Contrary to the highly insulating nature of bulk muscovites, the exfoliated nanosheets showed reduced bandgap energy which corresponds to semiconductor regime. The measured optical bandgap of the aluminosilicate ceramic nanosheets was 4.13 eV, which makes this ceramic nanosheet material a potential candidate for various electronic and electro-optic applications including wide bandgap semiconductors and photocatalysts.