Rich surface hydroxyl design for nanostructured TiO₂ and its hole-trapping effect

The surface hydroxyl groups in TiO₂ are crucial to many of its practical applications, but their controlled synthesis represents still a challenge. Herein, nanostructured TiO₂ with rich surface hydroxyl species groups and high crystallinity (TiO₂-OH) by high-temperature calcination have been developed by using the ionic liquid. Experimental measurements and theoretical calculations show a strong surface hydroxyl signal of two-dimensional ¹H TQ-SQ MAS NMR, as well as clear changes of the charge density of TiO₂ with the rich surface hydroxyl species. Moreover, the rich surface hydroxyl species groups in TiO₂ not only significantly enhance its performances involving photogenerated current, photocatalysis and energy strorage but also show a bright future on marine applications because of its high activity and stability in simulation seawater. The characteristics and mechanism have been proposed to clarify the generation of surface hydroxyl species of TiO₂ and the correponding directed hole-trapping at an atomic-/nanoscale.