Plasmon mediated SERS and photocatalysis enhancement in Au nanoparticle decorated 2D-TiSe2

Abstract

The combination of 2D materials and noble metallic nanostructure is becoming an attractive research domain for label-free, highly sensitive surface-enhanced Raman spectroscopy (SERS) applications. This study demonstrated photocatalysis degradation and SERS enhancements of organic fluorophore (Rhodamine 6G) on two-dimensional (2D) TiSe2 using Raman spectroscopy. The Au nanoparticles (NPs) were decorated on TiSe2 thin films by thermal annealing at variable temperatures. The selective deposition of Au NPs on the hexagonal TiSe2 nanocrystals increases surface roughness, creating a larger surface area for molecule adsorption. It has been observed that the Au decoration at 250 °C on TiSe2 exhibits efficient detection capabilities for R6G with the Raman intensity enhancement factors of the order of ≈105 along with the significantly improved visible light-induced photodegradation efficiency. The optimized Au NP size creates large electromagnetic hot spots produced by strong plasmon coupling that assists in the charge transfer mechanism among TiSe2, Au NPs, and R6G for enhanced SERS and photocatalysis activities. It has been observed that the intensity of Raman scattering decreases as the Au NP size increases on the TiSe2 material. A possible charge transfer mechanism is proposed with an energy band diagram. The simultaneous measurement of SERS and photocatalytic dye degradation in Au decorated TiSe2 can be used as a sensitive technique for water pollution treatment and biodegradable organic contaminants for the environmental ecosystem.