A ternary nanostructured α-Fe₂O₃/Au/TiO₂ photoanode with reconstructed interfaces for efficient photoelectrocatalytic water splitting

In this study, a ternary nanostructured α-Fe₂O₃/Au/TiO₂ film with integrating a crystalline α-Fe₂O₃ core, metallic Au nanoparticles (NPs), and an amorphous TiO₂ overlayer is fabricated and examined as a photoanode for photoelectrocatalytic water splitting. Under simulated solar illumination, the as-prepared photoanode exhibits a four-fold increase (1.05 mA cm⁻²) in photocurrent density at 1.23 V versus reversible hydrogen electrode (RHE) relative to bare α-Fe₂O₃. Based on systematic investigations, it is proposed that Au NPs extract photoholes from the bulk of α-Fe₂O₃ core and then shuttle them to the outer TiO₂ overlayer, and meanwhile, TiO₂ overlayer efficiently captures and stores the photoholes and facilitates the hole injection into electrolyte. Thus, the remarkably improved photoelectrocatalytic water splitting performance of α-Fe₂O₃/Au/TiO₂ photoanode is attributed to the significantly suppressed bulk and surface charge recombination due to the relayed pumping of the photogenerated charge carriers through the photoanode/electrolyte interfaces reconstructed by Au NPs and TiO₂ overlayer.