Synthesis of monolayer carbon-coated TiO2 as visible-light-responsive photocatalysts

Increasing visible light absorption and constructing an active surface for TiO 2 have long been pursued to obtain high photocatalytic activities. Modifying TiO 2 at an atomic scale is desirable to optimize its surface state and band structure but remains a huge challenge. Herein, we developed an ultrasmall (∼5 nm) visible-light-responsive TiO 2 photocatalyst with a novel hybrid structure (TiO 2 /C) through a chemical vapor deposition process on large scale. Environmental in-situ transmission electron microscope studies confirmed the anatase TiO 2 with a monolayer carbon shell in a hybrid structure. The resulted structure possesses narrowed bandgap 2.83 eV, favoring the enhanced visible-light-responsive photocatalytic activity. Density functional theory (DFT) simulations confirm the tunable mechanism of carbon-induced localized energy band within the bandgap of TiO 2 . As a physical barrier without turning TiO 2 black, the monolayer carbon shell stabilizes Ti 3+ inside TiO 2, facilitates the separation of photo-induced carriers and enriches abundant absorbing sites of target pollutants. Consequently, the TiO 2 /C exhibits outstanding photocatalytic performance in both photoelectrochemical water oxidation and dye degradation under visible light besides superior activity for hydrogen evolution under simulated sunlight irradiation. This design proved a meaningful strategy in obtaining visible-light-responsive photocatalysts with a stable active surface for industrial application.