MXene-intercalation induced ordered brick-mortar structures of allomorph junctions for enhanced flexibility in TiO2 nanofibers and photocatalytic efficiency

Continuous TiO2 nanofibers (NFs) with the merits of high photochemical activity, adjustable active sites, and easy to recycle have triggered a huge interest in the catalysis fields. Nevertheless, they are easy to break due to the intrinsic brittleness of ceramic TiO2. Here, we report a Mxene-intercalation toughening strategy to fabricate flexible TiO2 NF films with a sol–gel electrospinning method followed by a low-temperature calcination. The in-situ doping of MXene (Ti3C2Tx) nanosheets in TiO2 NFs reduces the grain sizes and introduces 2D defective MXene-derived TiO2 planes, the former creates sinuous grain boundaries that can reduce crack propagation, while the latter generates elastic brick–mortar structures of allomorph junctions that can absorb more external work. The dual functions remarkably enhance the breaking strength of TiO2 NFs from 0.06 to 0.16 MPa. Fascinatingly, this strategy reduces the bandgap of TiO2 and more efficiently conduct photogenerated carriers. The evolution rate of photocatalytic CO2 reduction into CH4 reaches 31.6 μmol/g/h without using sacrificing agents and photosensitizers. The reported facile strategy simultaneously enhances the flexibility of TiO2 nanofibers and photocatalytic efficiency.