A self-powered photoelectrochemical ultraviolet photodetector based on Ti 3 C 2 T x /TiO 2 in situ formed heterojunctions

Transition metal carbides and nitrides (MXenes), as a large family of emerging two-dimensional materials, have demonstrated extraordinary performance in many fields such as electronics, optics and energy storage. However, their susceptibility to oxidation during preparation and storage in ambient air environment is undesirable for long-term and stable applications. Here, we have demonstrated that the spontaneous oxidation of Ti₃C₂T_xcan be harnessed ingeniously to prepare Ti₃C₂T_x/TiO₂in situformed heterojunctions. Furthermore, a self-powered ultraviolet photodetector was constructed based on the photoelectrochemical performance of Ti₃C₂T_x/TiO₂heterojunctions. Since the highly conductive Ti₃C₂T_xcan promote the separation and transfer of photogenerated carriers in TiO₂, the prepared photodetector exhibits high responsivity (2.06 mA W^-1), short rise and decay times (45 and 69 ms) and long-term stability. This work demonstrates the controllable synthesis of Ti₃C₂T_x/TiO₂heterojunctions and provides a new promising potential of MXenes for photodetection applications.