Morphology engineering of rutile/anatase-TiO2 heterophase junctions for enhanced photoelectrochemical properties

TiO 2 is a promising photoelectrochemical (PEC) material as photoanodes for photoelectric conversion. However, severe charge recombination issues in TiO 2 significantly hinder the PEC efficiency and thus its application. It has been reported that the construction of rutile/anatase (R/A) heterophase junctions benefits fast charge transfer via interfaces and improves the efficiency of conversion. However, the evolution of R and/or A phases and their morphology and phase-transition effect on the PEC properties have not been investigated. In this study, unique TiO 2 heterophase junctions consisting of R-phase nanorods on the titanate-coexisting-phase (CO-phase) truncated octahedral particles were fabricated through a two-step hydrothermal method, where the morphology and phase transition of a titanate-coexisting phase was meticulously controlled and carefully monitored. The heterophase junctions exhibited superior PEC performances with a photocurrent density of 1.62 ± 0.05 mA cm −2 at 1.23 V, which was 4.3 times and 1.6 times greater than that of pure R phase and R-nanorod/A-nanosheet, respectively. This work demonstrates the potential of morphology engineering and phase transition of photoanodes for highly efficient photoelectric conversion.