Fracture of Ti3C2-TiO2 atomically thin films

MXene exhibits outstanding electrical conductivity, but its susceptibility to oxidation can impede its conductivity potential. While there is extensive research on the electrical, mechanical properties, and fracture behavior of pure MXene, the exploration of the oxidized MXene is rare, especially for the commonly observed Ti₃C₂-TiO₂ mixtures. In this study, we conducted molecular dynamics (MD) and Density Functional Theory (DFT) approaches and, for the first time, discovered three stable crystal structures of pure MXene with attached TiO₂ layers: Loose, Comb, and Tight. For each of these structures, we investigated the anisotropic mechanical and fracture behaviors based on two loading scenarios: ribbon and pre-cracked single layers. The results indicate that the anisotropic behavior is predominantly manifested in Loose and Tight structures. The structural asymmetry of Comb results in a larger and evolving cohesive zone. The direction of the TiO₂ layer-MXene interface bonds influences the material's strength, with the Tight structure exhibiting the highest resistance to fracture.