Plasmonic Metal Nanostructures Foster the Catalytic Performance of 2D Dichalcogenide Nanomaterials

Transition metal dichalcogenides (TMDs) are novel materials with unique optical, electrical, and chemical properties. These properties are determined by a band gap in the infrared and visible regions of the electromagnetic spectrum. A growing body of evidence indicates that TMDs can perform light-driven catalysis of chemical reactions. Furthermore, the rate and yield of such catalytic reactions can be altered by hybridization of TMDs with metallic nanostructures. However, the underlying mechanisms of such catalysis remain unclear, as does the extent to which the catalytic properties of TMDs can be modified by the metallic nanostructures. In this study, we utilized tip-enhanced Raman spectroscopy (TERS), a novel imaging approach with nanometer spatial resolution, to investigate how hybridization of tungsten disulfide (WS2) two-dimensional nanostructures with gold (Au) and silver (Ag) nanostructures alters their catalytic properties. Specifically, we measured the yield of p,p′-dimercaptoazobisbenzene (DMAB) formed on the surfaces of WS2, WS2@Au, and WS2@Ag decorated with 4-nitrobenzenethiol (4-NBT). Our results show that Ag nanostructures substantially enhanced DMAB-associated Raman response on WS2, whereas the enhancement observed on WS2@Au was considerably less pronounced. These results indicate that metallic nanostructures can be used to enhance the catalytic properties of TMDs. Our findings also indicate that the enhancement effect directly depends on the nature of the metal nanostructures hybridized with TMDs.