Vertically-Oriented WS2 Nanosheets with a Few Layers and Its Raman Enhancements

Abstract

Vertically-oriented two-dimensional (2D) tungsten disulfide (WS2) nanosheets were successfully grown on a Si substrate at a temperature range between and 550 °C via the direct chemical reaction between WCl6 and S in the gas phase. The growth process was carefully optimized by adjusting temperature, the locations of reactants and substrate, and carrier gas flow. Additionally, vertically-oriented 2D WS2 nanosheets with a few layers were tested as a surface-enhanced Raman scattering substrate for detecting rhodamine 6G (R6G) molecules where enhancement occurs from chemical enhancement by charge transfer transition from semiconductor). Raman spectra of R6G molecules adsorbed on vertically-oriented 2D WS2 nanosheets exhibited strong Raman enhancement effects up to 9.2 times greater than that on the exfoliated WS2 monolayer flake sample. From our results, we suggest that the WS2 nanosheets can be an effective surface-enhanced Raman scattering substrate for detecting target molecules.

Covalently Interconnected Polymer Dot–WS2 Nanosheet Heterostructure for Visible Light-Driven Hydrogen Production

“…In the comparative core level spectrum of W 4f of P-dots-SH/WS 2 , the W 4f binding energy peaks were observed at 35.66 eV (W 4f 7/2 ) and 36.22 eV (W 4f 5/2 ) but we have not observed any peaks related to W 4f in the spectrum of P-dots-SH (Figure S5a). 58 The core-level S 2p XPS spectrum of P-dots-SH (Figure S5b) showed three binding energy peaks at 161.6 eV (-SH), 163.5 eV (-SH), and 168.1 eV (oxidized sulfur), which slightly shifted to lower binding energies (161.4, 163.0, and 167.9 eV) compared to the deconvoluted S 2P peaks of P-dots-SH/WS 2 . The change in the binding energy of S 2p of P-dots-SH after the incorporation of P-dots-SH in exfoliated WS 2 nanosheets, as well as the W 4f binding energy peaks seen in P-dots-SH/WS 2 , suggest that P-dots-SH was successfully attached at the defective sites of the exfoliated WS 2 nanosheets.…”

Ultrafast photoresponse of vertically oriented TMD films probed in a vertical electrode configuration on Si chips

“…3(h)) reveals the W–O bonds at 36.0 and 38.1 eV in addition to the W 4f 7/2 (31.0 eV) and W 4f 5/2 (34.6 eV) doublets of the W–S bond. 38,39,44–47…”

“…3(h)) reveals the W-O bonds at 36.0 and 38.1 eV in addition to the W 4f 7/2 (31.0 eV) and W 4f 5/2 (34.6 eV) doublets of the W-S bond. 38,39,[44][45][46][47] While resolving sulfur-oxygen bonding from O 1s spectra is impossible, the S 2p spectra reveal the sulfur-oxygen bonding. For MoS 2 , the peaks (Fig.…”

The Role of GaN in the Heterostructure WS2/GaN for SERS Applications

“…Compared to the noble metals such as Au and Ag, which are commonly used for enhancing the SERS signal through the electromagnetic mechanism, the enhancement effect of the SERS signal using CM of WS 2 is weaker and limited [21]. Therefore, it is necessary to enhance the signal intensity by using nanostructures.…”