Anatase TiO 2 Quantum Dots with a Narrow Band Gap of 2.85 eV Based on Surface Hydroxyl Groups Exhibiting Significant Photodegradation Property

Anatase TiO 2 quantum dots (QDs) with surface hydroxyl groups and particle size below 3 nm were synthesized via a new synthetic route and showed a low band‐gap energy of 2.85 eV and good dispersibility in an aqueous system. This material exhibited significantly high photocatalytic activity for the degradation of methyl orange (MO). The photocatalytic activity of TiO 2 QDs was 16 times higher than that of commercial P25 at an initial MO concentration of 50 mg L –1 in the reaction system. At a concentration of 10 mg L –1 , MO could almost be completely removed within 1 min. The high photocatalytic activity could be attributed to the low band‐gap energy, large surface area, and good aqueous dispersibility of the anatase TiO 2 QDs.