Raman enhancement effect using 2D materials as substrates: mechanism and application*

Graphene enhanced Raman scattering (GERS) was first reported in our previous work in 2010, which opened the door of using 2D materials as substrates for Raman enhancement. Here, we will present a systematic study on the Raman enhancement effect on a variety of 2D materials. Raman enhancement effect at different levels is observed on different 2D materials, which is attributed to the chemical enhancement. The degree of charge transfer between molecule and 2D materials is obtained based on the selection rule of the enhancement to vibrational modes with distinct symmetries. A strong correlation is found between the Raman enhancement effect and the degree of charge transfer. Moreover, advantages of the Raman enhancement on 2D materials for practical applications will be discussed.