Black TiO₂ for Solar Hydrogen Conversion

Titanium dioxide (TiO₂ ) has been widely investigated for photocatalytic H₂ evolution and photoelectrochemical (PEC) water splitting since 1972. However, its wide bandgap (3.0–3.2 eV) limits the optical absorption of TiO₂ for sufficient utilization of solar energy. Blackening TiO₂ has been proposed as an effective strategy to enhance its solar absorption and thus the photocatalytic and PEC activities, and aroused widespread research interest. In this article, we reviewed the recent progress of black TiO₂ for photocatalytic H₂ evolution and PEC water splitting, along with detailed introduction to its unique structural features, optical property, charge carrier transfer property and related theoretical calculations. As summarized in this review article, black TiO₂ could be a promising candidate for photoelectrocatalytic hydrogen generation via water splitting, and continuous efforts are deserved for improving its solar hydrogen efficiency.