Surface Modification of TiCN MXene and Their Enhanced Performance in Photodetection.

As a typical hetero-MXene, TiCN MXene has attracted great attentions owing to its ultrafast carrier dynamic and unique nonlinear optical response. However, the photo-response of pristine TiCN is unsatisfied due to the fast carrier recombination. Herein, multi-layer TiCN MXene is modified with well-dispersed Bi quantum dots, where the TiCN@Bi heterojunction can not only tune the optical absorption but also introduce energy transfer channels. The built-in electric field endows TiCN@Bi self-powered response behavior and the performance can be further enhanced by tuning external conditions. As demonstrated, the TiCN@Bi-based photodetectors exhibit high photocurrent density (18.24 µA cm) and excellent photoresponsivity (18.32 mA W). In addition, the device shows fast response and outstanding stability (0.002% for each cycle), holding great potentials for practical applications. Hence, this work not only highlights the broad prospects of MXene-based heterojunction, but also provides great value for other optoelectronic device applications.