Laser-induced deposition of Ni, Co-doped FeOOH cocatalysts on WO₃ photoanodes and elucidating their roles in water oxidation in terms of carrier dynamics

Oxygen evolution cocatalysts (OECs) are frequently integrated with monoclinic WO₃ photoanodes to improve their photoelectrochemical (PEC) water-splitting performance. In this study, we propose laser-induced catalyst deposition (LICD) for the deposition of FeOOH and doped FeOOH OECs on WO₃ photoanodes. Furthermore, the roles of OECs in PEC water-splitting are examined in terms of carrier dynamics using ultrafast time-resolved photoluminescence (TRPL) analyses. The highlight of the TRPL study is using shortpass and longpass optical filters to show that the OECs extend the lifetime of holes excited from low-lying states. As a result, it is considered that the OECs provide hole-storing trap states within the bandgap to increase the number of long-lived holes, resulting in improved PEC performance of WO₃ photoanodes.