Facile Synthesis of {101}, {010} and [111]‐Faceted Anatase‐TiO 2 Nanocrystals Derived from Porous Metatitanic Acid H 2 TiO 3 for Enhanced Photocatalytic Performance

The cuboid‐like anatase TiO 2 nanocrystals with co‐exposed {101}/[111]‐facets and the irregular anatase TiO 2 nanocrystals with co‐exposed {101}/{010} facets were hydrothermally synthesized by using porous metatitanic acid H 2 TiO 3 as the precursor and the HF, H 2 O 2 and NH 3 ⋅H 2 O as the capping agent and solvent. The as‐prepared anatase TiO 2 nanocrystals were characterized by the powder X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high‐resolution transmission electron microscopy (HRTEM), selected‐area electron diffraction (SAED) and Nitrogen adsorption/desorption measurements. The transformation from the porous structure of metatitanic acid H 2 TiO 3 to anatase TiO 2 nanocrystals may experience three types of reactions including dehydration reaction from [TiO 3 ] 2− layers, [TiO 6 ] 8− octahedral monomers along the edge‐shared oxygen atoms, the formation of anatase nucleus, and the growth of anatase nucleus along the [101]‐direction and [011]‐direction (or [‐10‐1]‐direction and [0‐1‐1]‐direction) during the hydrothermal reaction process. Furthermore, the photocatalytic activities of the as‐prepared anatase nanocrystals were evaluated by the photocatalytic degradation of the typical carcinogenicity pollutant Rhodamine B (RB) under UV‐light irradiation at room temperature in air. The T180‐TiO 2 nanocrystals exhibits the most excellent photodegradation performance than the T150‐TiO 2 , T160‐TiO 2 , T180‐TiO 2 anatase nanocrystals and the commercially available P25‐TiO 2 nanocrystals for the degradation amount of RB per unit surface area of catalyst (mg(RB) per m 2 (TiO 2 surface area)), which can be ascribed to its high percentage of the {010}/[111]‐crystal facets.