A Photoresponsive Rutile TiO₂ Heterojunction with Enhanced Electron-Hole Separation for High-Performance Hydrogen...

Rutile titanium dioxide (TiO₂ ) 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 TiO₂ owing to its higher recombination rate of electron-hole pairs. To effectively separate the electron-hole pairs in rutile TiO₂ , a facet heterojunction (FH) structure to prolong the lifetime of the photogenerated electrons is proposed. Ultrathin TiO₂ nanosheets with different facets are coated in situ onto TiO₂ nanorod (NR) substrates, where FHs are built among the nanosheets as well as between the nanosheets and NR substrates. The as-prepared rutile TiO₂ , with an FH structure (FH-TiO₂ ), serves as an effective photocatalyst for water splitting. More than 45 and 18 times higher photogenerated current density and H₂ production rate, respectively, are obtained compared to those of pure rutile TiO₂ NRs. Moreover, FH-TiO₂ delivers a 0.566 mmol g^-1 h^-1 H₂ production rate even in pure water. This study offers important insights into the rational design of rutile TiO₂ structures for highly efficient photocatalytic reactions.