Preparation of hematite with an ultrathin iron titanate layer via an in situ reaction and its stable, long-lived, and excellent photoelectrochemical performance

•A facile and in situ method is proposed to prepare a high-performance Fe2O3/Fe2TiO5 photoanode.•The method based on a reaction of tetrabutyl titanate with electro-reduced Fe film.•Microstructural defects and impurities are avoided since the preparation route of FeOOH film as substrate is not used.•As-prepared Fe2O3/Fe2TiO5 photoanode shows excellent PEC performance with a considerable enhancement in photocurrent density.•A good long-term stability under both neutral and alkaline conditions was obtained.

In this work, a facile and in situ method is proposed to prepare a high-performance photoanode with an ultrathin Fe2TiO5 layer on hematite by the reaction of tetrabutyl titanate with electro-reduced Fe film, which avoids using FeOOH film as substrate. The preparation involves 30 s of direct electro-reduction (ER) of Fe film and 3 min of a sol method, followed by thermal treatment. The as-prepared photoanode shows a significant enhancement of the photocurrent density to ∼2.0 mA/cm2 (1.23 V vs. RHE). The incorporation of a Co/Pi catalyst resulted in a photocurrent density of ∼3.05 mA/cm2. The high photoelectrochemical performance can be attributed to the low microstructural defects, the better carrier separation and faster electron transfer based on electrochemical impedance spectroscopy (EIS) and Intensity-modulated photocurrent spectroscopy (IMPS) analysis. In addition, the prepared photoanode shows good stability under both alkaline and neutral conditions.

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