High-Efficiency Photo-Induced Charge Transfer for SERS Sensing in N-Doped 3D-Graphene on Si Heterojunction

Nitrogen-doped three-dimensional graphene (N-doped 3D-graphene) is a graphene derivative with excellent adsorption capacity, large specific surface area, high porosity, and optoelectronic properties. Herein, N-doped 3D-graphene/Si heterojunctions were grown in situ directly on silicon (Si) substrates via plasma-assisted chemical vapor deposition (PACVD), which is promising for surface-enhanced Raman scattering (SERS) substrates candidates. Combined analyses of theoretical simulation, incorporating N atoms in 3D-graphene are beneficial to increase the electronic state density of the system and enhance the charge transfer between the substrate and the target molecules. The enhancement of the optical and electric fields benefits from the stronger light-matter interaction improved by the natural nano-resonator structure of N-doped 3D-graphene. The as-prepared SERS substrates based on N-doped 3D-graphene/Si heterojunctions achieve ultra-low detection for various molecules: 10⁻⁸ M for methylene blue (MB) and 10⁻⁹ M for crystal violet (CRV) with rhodamine (R6G) of 10⁻¹⁰ M. In practical detected, 10⁻⁸ M thiram was precisely detected in apple peel extract. The results indicate that N-doped 3D-graphene/Si heterojunctions based-SERS substrates have promising applications in low-concentration molecular detection and food safety.