“…This is believed to be mainly due to inherent characters, for example, short hole diffusion length (2–4 nm), low absorption coefficient (∼10 5 cm –1 at 566 nm), , and inefficient water oxidation competed by the rapid capture of holes by the Fe 3+ e g 2 level, which lies above the top of the O 2p 6 band . The issues on these inherent characters of α-Fe 2 O 3 would be broken through by doping of another element to the lattice of α-Fe 2 O 3 to enhance the hole diffusion length, nanostructure control, and heterojunction formation to enhance the charge separation efficiency and modifying with a catalyst to improve the water oxidation reaction at the surface. − Nevertheless, there is still room to improve the performance of the state-of-the-art pristine α-Fe 2 O 3 photoanodes for PEC water oxidation, as indicated in Table S1, − including the highest IPCE (IPCE 420 ) of 36% at 420 nm for cauliflower α-Fe 2 O 3 prepared by the atmospheric pressure chemical vapor deposition (APCVD) technique . Although α-Fe 2 O 3 -based photoanodes have been fabricated via various physical and chemical techniques such as chemical vapor deposition, − ultrasonic spray pyrolysis, atomic layer deposition, dense solution-based regrown, e-beam evaporation, electrodeposition, and hydrothermal, a facile way available for mass production of α-Fe 2 O 3 photoanodes is mandatory for practical systems of solar-driven water splitting.…”