Functionalization-Driven Formation of TiO ₂ /Ti ₂ CT _<i>x</i> Interfaces

In this study, the nature of the interface between TiO₂ and MXenes was systematically explored by using density functional theory and taking Ti₂C as a case study. TiO₂/MXene interfaces are emerging as potential photoactive systems, but a deep understanding of their nature is often elusive. Our findings reveal that MXene surface functionalization predominantly governs the interaction between TiO₂ and MXenes. Specifically, when the Ti₂C MXene is terminated with -H or -OH or when it is not functionalized, the formation of the interface leads to a strong interaction due to the formation of new chemical bonds. Weak van der Waals interactions are present when the Ti₂C MXene surface termination involves -F, -Cl, or -O groups. The analysis of the interface polarization shows a systematic charge transfer from MXene surfaces toward TiO₂, which is localized at the interface and influenced by MXene functionalization. The results of this study provide new atomistic insights on the interaction between these two materials, helping the understanding of the nature of this emerging class of photoactive materials.