First principles modeling of composites involving TiO₂ clusters supported on M₂C MXenes

First-principles calculations based on density functional theory are performed to investigate the formation of titania/MXene composites taking (TiO₂)₅/M₂C (M = Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W) as cases of study. The present systematic analysis confirms a favorable, high exothermic interaction, which promotes important structural reconstructions of the (TiO₂)₅ cluster along with charge transfer from the MXene to titania. MXenes composed of d³ transition metals promote the strongest interaction, deformation energy, and charge transfer, followed by d⁴ and d⁵ M₂C MXenes. We provide evidence that the formation of these (TiO₂)₅/M₂C composites is governed by charge transfer, leading to scaling relationships. By using the electronegativity of the metal composing MXene and the MXene d-band center, we also establish linear correlations that can be used to predict the interaction strength of (TiO₂)₅/M₂C composites just from the knowledge of the MXene composition. It is likely that the present trends hold for other TiO₂/MXene composites.