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.