Band structure of graphene modulated by Ti or N dopants and applications in gas sensoring

The exploration of novel sensors for NO₂ detection is particularly important in material and environmental sciences. In this work, the HOMO-LUMO gap of graphene, Ti- or N-doped graphene is investigated by DFT methods. The adsorption of NO₂, NO, and O₂ on Ti- or N-doped graphene of different sizes is also explored. Results reveal that the interactions between gases (NO₂, NO, and O₂) and Ti- or N-doped graphenes is not affected by the size of graphene. The doped Ti greatly improves the interactions between gases and graphene whereas the doped N has no effect on those interactions. The HOMO- LUMO gap of Ti-doped graphene can be modulated by adsorption of the gases. The cross effect of the NO and O₂ is also investigated, and it is demonstrated that Ti-doped graphene has specific interactions with NO₂. Thus, Ti-doped graphene can be a candidate for NO₂ sensor materials. Furthermore, doping the graphene with Ti or N improves the sensitivity of the sheets toward NO₂, which can be trapped and detected by the intrinsic graphene. Efficient sensors are rationally designed to diversify their applications in environmental science and engineering.