Improving Photocatalytic H2 Evolution of TiO2 via Formation of {001}–{010} Quasi-Heterojunctions

The coexistence of low-index facets with a highly photoactive {001} facet in anatase TiO 2 nanocrystals has been recently found beneficial to enhance the photocatalytic performance of TiO 2 via a synergistic effect. In this paper, this synergistic effect has been further extended from a single crystal to interconnected nanocrystals with dominating {001} or {010} facet in intact hierarchical TiO 2 nanostrucutre. The particles synthesized at the optimal condition showed outstanding photocatalytic hydrogen production of 364.2 μmol·g –1 ·h –1, which is about four times as much as that of commercial P25 (96.5 μmol·g –1 ·h –1 ). Femtosecond transient spectroscopy and density functional theory (DFT) study indicates that effective electron–hole separation takes place within these nanostructures. This new prototype of synergy, which we denote as quasi-heterojunctions, shows that enhanced photocatalytic performance could be derived in the same anatase phase by synthesizing appropriate faceted nanostructures. This work provides a new dimension to facet engineering of TiO 2 and other semiconductor photocatalysts.