Review on MXene/TiO2 nanohybrids for photocatalytic hydrogen production and pollutant degradations

MXenes have grabbed considerable research attention in photocatalytic field owing to their regular planer structure, elemental composition, excellent metal conductivity, surface termination groups and abundant derivatives. MXene-derived and based materials deliver motivation for fabrication of novel photocatalysts with optimum activity, and long term stability. Meanwhile, TiO2 being the most extensively studied photocatalyst for solar light driven water splitting and environmental remediation, owing to its noble photocatalytic activity, low cost, nontoxicity, and copious availability. Nevertheless, the major drawbacks of TiO2 based systems are its ultra-wide band gap and rapid recombination of photoinduced charge carriers. In this context, MXene have been rigorously explored for the modification of TiO2 which includes the MXene derived TiO2 (in-situ derived TiO2 from MXene) and MXene/TiO2 based nanocomposite (externally added TiO2 with MXene) for easy channelization of electrons owing to the metal-semiconductor contact where MXene can behave as a co-catalyst or support by enhancing the overall activity. Although a few reviews have been published highlighting the synthesis, inherent properties and applications in various fields, but this particular review highlights the recent advances of the adopted synthetic routes to develop MXene-derived TiO2 and MXene/TiO2 based nanocomposite, explaining the mechanism of charge carrier separation due to the formation of schottky junction at the interface of electrically conductive Ti3C2 and optically active TiO2 for achieving outstanding photocatalytic hydrogen (H2) evolution and pollutant degradation. Furthermore, the future challenges including the materials design process and to improve the overall activity for the promotion of MXenes derivative and allied materials has been proposed with correlating the structural features and activity.