Nanoscale Anatase TiO₂ With Dominant {111} Facets Shows High Photocatalytic Activitys And Photocatalytic Selectivity

It is well known that the surface morphology of TiO2 have a critical impact on its photocatalytic properties. In this work, we report a novel synthesis of nanoscale anatase TiO2 with dominant highly active {111} facets by a simple one-step hydrothermal route with the assistance of NH4 F and HF. In this progress,the exposed crystal facets of TiO2 can been directly tuned by controlling the mole ratio of NH4+ and F-.When the mole ratio of NH4+ and F-reach 1:2, nanoscale anatase TiO2 with dominant {111} facets can be obtained. Nanoscale anatase TiO2 with exposed {101} or {001} facets will be prepared when there is only ammonia or HF added respectively. Such nano-TiO2 with exposed highly active {111} facets has large speci?c surface area and shows excellent photocatalytic activity: as much as 2–3 times than that of TiO2 nanosheets with exposed {001} facets and commercial Degussa P25 which con?rms the {111} facets have higher photocatalytic activity than {001} and {101} facets. The higher photocatalytic activity of {111} facets can be ascribed to the fact that all Ti and O atoms on the surface are unsaturated Ti5 c, Ti3 c and O2 c modes which produces a higher adsorption and degradation ability.At the same time, we demonstrate the photocatalytic selectivity of nanoscale anatase TiO2 that obtain through one-step hydrothermal route. After {101}, {111}, and {001} facets exposed nanoscale anatase TiO2 were obtained, then a calcined progress to clear surface adsorbent atoms. Results reveal that {101} exposed Ti O2 has some remain binding N with a mode of unsaturated N3 c exhibits selectively photocatalytic degradation of methylene orange(MO) in a methylene blue(MB) and methylene orange(MO) mixed solution, whereas TiO2 wit exposed {111} and {001} facets exhibits photocatalytic selectivity for MB. The {111} facets of anatase TiO2 exhibit a better photocatalytic selective ability than {001} facets. It con?rms that the photocatalytic selectivity can be affected by different dominant crystal facets: In a deeper analysis, there are many unsaturated O2 c on the surface of {001} and {111} facets, which enhances adsorbent selectivity and relevant photocatalytic activity of MB, at the same time, the unsaturated O2 c on the surface of {111} facets is much more than that on the surface of {001} facets results in a better photocatalytic selectivity of {111} facets.Our research provides a method to synthesis of nanoscale material with dominant highly active facets by a simple one-step hydrothermal route, at the same time,we hope to develop a new light catalytic selection approach and provide a deeper understanding of different ecposed facts of anatase TiO2,and we hope the matrrial can also be applied in photocatalysis, solar battery and sensors, and other fields.