Hydrogenated Amorphous Titania with Engineered Surface Oxygen Vacancy for Efficient Formaldehyde and Dye Removals under Visible-Light Irradiation.

Hydrogenated crystalized TiO with oxygen vacant (O) doping has attracted considerable attraction, owing to its impressive photoactivity. However, amorphous TiO, as a common allotrope of titania, is ignored as a hydrogenated templet. In this work, hydrogenated amorphous TiO (HAm-TiO) with engineered surface O and high surface area (176.7 cm g) was first prepared using a unique liquid plasma hydrogenation strategy. In HAm-TiO, we found that O was energetically retained in the subsurface region; in particular, the subsurface O-induced energy level preferred to remain under the conduction band (0.5 eV) to form a conduction band tail and deep trap states, resulting in a narrow bandgap (2.36 eV). With the benefits of abundant light absorption and efficient photocarrier transportation, HAm-TiO coated glass has demonstrated superior visible-light-driven self-cleaning performances. To investigate its formaldehyde photodegradation under harsh indoor conditions, HAm-TiO was used to decompose low-concentration formaldehyde (~0.6 ppm) with weak-visible light (λ = 600 nm, power density = 0.136 mW/cm). Thus, HAm-TiO achieved high quantum efficiency of 3 × 10 molecules/photon and photoactivity of 92.6%. The adsorption capabilities of O (-1.42 eV) and HCHO (-1.58 eV) in HAm-TiO are both largely promoted in the presence of subsurface O. The surface reaction pathway and formaldehyde decomposition mechanism over HAm-TiO were finally clarified. This work opened a promising way to fabricate hydrogenated amorphous photocatalysts, which could contribute to visible-light-driven photocatalytic environmental applications.