Enhancement mechanism of sodium storage performance in F, S doped graphene/WS2 heterostructures: A first-principles study

In this work, first-principles calculations were carried out to construct F-doped, S-doped and co-doped graphene/WS 2 heterostructures, and to investigate the effects of doping on their structural properties, electronic characteristics, and Na adsorption behavior. The results show that the introduction of graphene preserves the semiconducting nature of the system while reducing the effective bandgap of WS 2 . The formation energies of F, S, and co-doped systems are all negative, indicating thermodynamically spontaneous processes. F doping induces local structural distortion, S doping increases the interlayer spacing, and co-doping achieves a balance between structural distortion and stability. Regarding Na adsorption, the F-doped system exhibits the strongest adsorption, while the co-doped system provides both strong adsorption capability and structural tunability. Optical property analysis reveals that S doping and co-doping significantly enhance light absorption in the 4–10 eV photon energy range, and co-doping further increases the static dielectric constant, which is beneficial for carrier separation. This study provides theoretical guidance for the application of such heterostructures in sodium-ion storage electrodes and optoelectronic devices.