Ultrasonic passivated hematite photoanode with efficient hole transfer pathway for enhanced photoelectrochemical water oxidation

Hematite is an ideal photoanode candidate for its appropriate energy band position, small band gap and good stability. However, sluggish charge carriers transport process and severe recombination reaction caused by surface and interface flaws always leads to inferior photoelectrochemical performance. In this study, we synthesized a SnO₂ passivation layer with several-nanometer thickness on Fe₂O₃ nanorod arrays by a facile sonochemical method. And such passivated Fe₂O₃ was labeled as T-Fe₂O₃. After ultrasonic treatment, the surface chemical state of Fe₂O₃ was availably adjusted by SnO₂ layer, the as-prepared T-Fe₂O₃ photoanode exhibits a 28-fold increase in photocurrent density compared with pristine Fe₂O₃ photoanode under simulated solar illumination. Based on systematic investigations, it is found that SnO₂ layer efficiently compensates the surface states on Fe₂O₃, prolonging charge carrier lifetime and promoting charge separation greatly. As a result, the remarkably improved photoelectrochemical water splitting performance of T-Fe₂O₃ is attributed to unrestrained and fast hole transport way provided by SnO₂ mediated photoanode/electrolyte interface.