**3. Conclusion**

In summary, a DFT study is introduced on the SERS of TiO2 adsorbed Gold/ Graphene by different Graphene based Substrates. Different types of graphene substrate cluster (perfect graphene, graphene with B- and N-doped graphene) were included to check the influence of graphene surface on spectral and energy properties. TiO2/ GB-Au complex exhibited the largest chemical enhancement in calculated static Raman spectrum. The excitation properties including the transition states and preresonance Raman spectra were calculated, which shows the effect of the transition state on the resonance chemical enhancement as well as the relationship between the excitation energy and the non-resonant chemical enhancement. The HOMO and LUMO energy of TiO2/GB-Au complex was the largest energy (0.15869) which indicated the greater stability of the molecule. The knowledge profited from this study is expected to be help to both graphenebased SERS study and ultrasensitive spectroscopic techniques.
