Electron Storage in Monolayer Tungstate Nanosheets Produced via a Scalable Exfoliation Method.

Inorganic nanosheet materials with atomic thinness have been widely studied as (photo)catalytic materials due to their unique electronic states and surface structures. One scalable and reproducible method of producing monolayer nanosheets is a top-down approach based on the exfoliation of layered parent compounds using an alkylammonium solution as a surfactant. However, H 2 W 2 O 7 layered tungstates dissolve in basic aqueous solutions, making them unsuitable for the exfoliation process. This work proposes a scalable method to obtain monolayer WO 3 nanosheets with a very high external field responsiveness. This work shows that H 2 W 2 O 7 topochemically swells in a concentrated octylamine (C 8 N 17 NH 2 ) aqueous solution with a concentration above the solubility of octylamine in water. Water was added for exfoliation of the liquid crystalline phase into isolated W 2 O 7 2- nanosheets with octylammonium (C 8 N 17 NH 3 + ) protection. Crystalline WO 3 nanosheets on the n-Si substrate obtained with calcination exhibited electron richness in the conduction band due to static electron transfer at the interface.