Combined Effect of Underlayer and Deposition Solution to Optimize the Alignment of Hematite Photoanodes

This study investigates the optimization of hematite (α-Fe₂O₃) photoanodes for enhanced photoelectrochemical (PEC) performance and reproducibility, which are crucial for photocatalytic applications. Despite hematite's potential, hindered by inherent limitations, significant improvements were realized by introducing a titanium dioxide (TiO₂) underlayer and ethanol-modified deposition. The influence of the deposition methods was understood by potential-dependent photoelectrochemical impedance spectroscopy analysis. The introduction of the TiO₂ underlayer effectively increased the density of states, preferable for the electron transport in the bulk hematite, and the ethanol deposition on a TiO₂ underlayer led to a stable surface state formation (S1 state) for the photoexcited hole transfer. This analysis illuminated the intricate interplay between electron transport in the bulk and photogenerated hole transfer at the solution interface, thereby facilitating smoother charge transfer. These findings underscore the viability of surface engineering and meticulous process optimization in addressing critical challenges in photocatalyst development.