Preparation of WS₂Nanohybrids for Photocatalyzed Redox Reactions of Organic Molecules

Abstract

Monolayers of transition metal dichalcogenides (TMD), such as MoS2 and WS2 nanosheets, have recently attracted great attention as promising materials for electronic devices, photocatalysts and optical biosensors. Their unique electronic and optical properties can be modulated via various functionalization methods designed for a specific application of interest. In this study, WS2 nanosheets were modified with plasmonic silver nanoparticles (AgNPs) for photocatalysis and functional polymers for biosensing. First, the size of AgNPs on WS2 nanosheets were controlled by varying the molar ratio of capping reagent and reductant, which gave rise to size-controlled AgNP@WS2 nanohybrids. In addition, their photocatalytic activities in 4-nitrophenol reduction was investigated in terms of AgNPs size through sufficient control experiments and scientific analyses. These AgNP@WS2 nanohybrids exhibited enhanced photocatalytic performance, which was superior to other preceding photocatalytic system. Second, boronic acid-modified poly(vinyl alcohol) (B-PVA) was synthesized via esterification and this functional polymer was utilized for aqueous exfoliation of bulk WS2 to form polymer-functionalized WS2 nanosheets. B-PVA-WS2 hybrids selectively detected glycated hemoglobin exploiting their water-stable photoluminescence, which offers a simple and rapid detection platform for precise diagnosis of diabetes mellitus. Hence, it was possible to modulate the optical properties of WS2 nanosheets by these two ways for the desired application. Noble metal deposition brought an increment in catalytic activity toward WS2 nanosheets, while the functional polymer was anchored on the WS2 nanosheets retaining their biological activities. It is expected that these novel synthetic approaches for the functionalization of WS2 nanosheets will be widely applied for other TMD materials with tunable optical properties.