Scheme 1. Simplified energy diagrams and processes involving photogenerated charges following UV laser excitation of α-Fe₂O₃ and α-Fe₂O_3–x under a positive bias. Rate constants are those determined at 1.4 V_RHE as described in the main text. In contrast to α-Fe₂O₃ which has been air annealed, no slow recombination between surface accumulated holes and bulk electrons (k_BET) is observed for α-Fe₂O_3–x.