Surface-enhanced Raman scattering by hierarchical CuS microflowers: Charge transfer and electromagnetic enhancement

The research of surface enhanced Raman scattering (SERS) based on semiconductor substrate expends the application field of SERS technology. However, the relatively low enhancement sensitivity of semiconductor materials is still a problem to be solved urgently. Herein, high-performance enhancement of Raman scattering is achieved through hierarchical CuS microflowers. Simultaneously based on electromagnetic near-filed effect and charge transfer effect between the reporter molecule and CuS material system, the enhancement factor can reach 105 and the detection limitation is as low as 10−8 M for MG and 10−7 M for CV and R6G molecules. The enhancement sensitivity is proved to be related to the number and spacing of petals of the CuS flowers, and illumination of the incident wavelength. A finite integration method is conducted to estimate the electromagnetic field around the CuS microflower system. The ground-state properties of the system are calculated by DFT method. The energy level schematic diagram of the probe molecules on CuS system is employed to investigate the charge transfer process between the reporter molecule and CuS microflower system. Due to the unique properties of semiconductors, such as surface functionalization, stable material properties and degradability, CuS microflower can be served as a high-performance SERS platform to expend the application field of SERS, and is a valuable tool for the research of semiconductor surfaces.