Ferroelectric enhanced photoelectrochemical water splitting in BiFeO3/TiO2 composite photoanode

A facile sol-gel methodology was used to synthesize single-phase BiFeO3 (BFO) film on TiO2 photoanode to improve photoelectrochemical (PEC) water-splitting efficiency. The BFO films with controllable thickness induced a considerable ferroelectric polarization under bias voltage, which effectively tuned the electric band bending of BFO/TiO2. The photocurrent density of the as-prepared BFO-5/TiO2could reach up to 11.25 mA/cm2, which is over 20 times higher than that of bare TiO2. Moreover, the positively poled BFO-5/TiO2 photoanode yielded a photocurrent density of 28.75 mA/cm2 at 1.5 V vs.SCE under AM 1.5G illumination. This work suggests that BFO/TiO2 with combined ferroelectric and semiconducting features could be a promising solution to improve PEC performance by concurrently promoting the light absorption and charge-separation and transportation properties.