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.