TiO2-rutile/anatase homojunction with enhanced charge separation for photoelectrochemical water splitting

The mismatched interfaces of heterojunction usually have lots of defects, deriving in recombination of generated electron-hole pairs. On the other hand, homojunction interfaces are considered to be beneficial to the separation of charge carriers due to the similar characteristics in two sides of homojunction. TiO2 have rutile and anatase two typical photoactive phases in nature. In this work, TiO2-rutile/anatase (TiO2-R/A) homojunction photoanode is fabricated by in situ growth of anatase TiO2 on TiO2-R surface. By contrast with TiO2-rutile/rutile (TiO2-R/R) photoanode, TiO2-R/A displays higher photocurrent density (1.70 mA cm−2 at 0.6 V vs. SCE). Deep insight into the mechanism suggests that TiO2-R/A homojunction has intense band bending and enhanced surface area, which facilitate the charge separation and transmission. This study offers some novel insights to design and fabricate semiconductors photoanodes for highly efficient photocatalytic reactions.