Plasma-induced enhancement of light–matter interaction on graphene–MoS₂ heterostructure for sensitive SERS sensing

There has been a perpetual pursuit of improved sensitivity and reproducibility in surface-enhanced Raman scattering (SERS) devices. The two-dimensional material-based, metal-free SERS platform has emerged as a promising option due to the atomically flat surface and diverse surface electronic states. However, the inherently low light absorption efficiency and limited electronic state density lead to unsatisfactory sensitivity. Here, a metal-free, reusable, and plasma-treated graphene–MoS₂ heterostructure as a SERS platform for high-sensitivity molecule detection is proposed. The heterostructure exhibits excellent SERS performance with a limit of detection as low as 10⁻⁹ M for probe molecules. The plasma treatment changes the electronic and structural properties of the heterostructures, increasing the charge transfer (CT), facilitated by the modified surface chemistry and light absorption rate, resulting in a more effective light–matter coupling and stronger signal enhancement. Furthermore, the structural disorders are created by the plasma irradiation, leading to the generation of local dipoles and hence enhancing the photoinduced CT. The results provide alternative avenues for developing low-cost and high-performance SERS devices.