A Photoresponsive Rutile TiO Heterojunction with Enhanced Electron-Hole Separation for High-Performance Hydrogen Evolution.

Rutile titanium dioxide (TiO ) is a promising photocatalyst due to its high thermodynamic stability and few intragrain defects. However, it has not yet achieved photocatalytic activity comparable to that of anatase TiO owing to its higher recombination rate of electron-hole pairs. To effectively separate the electron-hole pairs in rutile TiO , a facet heterojunction (FH) structure to prolong the lifetime of the photogenerated electrons is proposed. Ultrathin TiO nanosheets with different facets are coated in situ onto TiO nanorod (NR) substrates, where FHs are built among the nanosheets as well as between the nanosheets and NR substrates. The as-prepared rutile TiO , with an FH structure (FH-TiO ), serves as an effective photocatalyst for water splitting. More than 45 and 18 times higher photogenerated current density and H production rate, respectively, are obtained compared to those of pure rutile TiO NRs. Moreover, FH-TiO delivers a 0.566 mmol g h H production rate even in pure water. This study offers important insights into the rational design of rutile TiO structures for highly efficient photocatalytic reactions.