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

•High-performance enhancement of Raman scattering based on hierarchical CuS microflower is achieved.•The enhanced sensitivity related to the number and spacing of petals of CuS and illumination of incident wavelength.•The enhancement effect induced by the electromagnetic near-filed effect and CT between the reporter molecule and CuS.