Boosting synergistic hole separation and transfer in the TiO2-MXene photoanode by depositing amorphous NiOOH/CoOOH cocatalysts

The efficient separation and transport of photogenerated charge carriers within the photoanode are pivotal for achieving high-performance photoelectrochemical (PEC) water splitting. In this study, TiO2-MXene nanowire arrays (NWAs) adorned with amorphous CoOOH/NiOOH (CN) were fabricated using hydrothermal and photo-assisted electrodeposition techniques. TiO2-MXene-CN NWAs demonstrated a photocurrent density of 1.51 mA/cm(2) at 1.23 V versus the reversible hydrogen electrode (vs. RHE), which is 1.46 times and 2.79 times that of TiO2-CN and TiO2, respectively. Electrochemical impedance spectroscopy, photoluminescence, time-resolved photoluminescence, and Mott-Schottky analysis unveiled that the incorporation of MXene and CN substantially augmented the separation of photogenerated electron-hole pairs and efficient charge carrier utilization. Furthermore, the loading of MXene-CN layers ameliorated the light absorption performance of bare TiO2 NWAs. This work provides valuable insights for the design of photoelectrodes employing wide-bandgap materials.