Enhanced Photocatalytic Performance of HTO/TiO2 Composites Prepared by Hydrothermal Soft Chemical Synthesis Under UV Irradiation

Abstract White metatitanic acid H 2 TiO 3 (HTO)/TiO 2 composites with co‐exposed [111]‐, {010} and {101} facets were successfully synthesized by employing the white suspension of [TMA + ] 2 [TiO 3 ] 2− as the precursor via a hydrothermal soft chemical synthesis method in the presence or absence of 1‐ethyl‐3‐methylimidazolium bromide ([Emim]Br), 4‐bromine imidazole (Bmim) and 1‐methyl‐3‐propylimidazole tetrafluoroborate ([Pmim]BF 4 ) ionic liquids. The structure, morphology, specific surface areas, microstructure, surface properties, and charge migration behaviors of HTO/TiO 2 composites vary depending on the selected ionic liquid. The apparent rate constant of the Bmim‐HTO/TiO 2 composite was the highest, at 0.0353 min −1 , which was approximately 1.35, 1.38, 1.44, 2.67, and 88.25 times higher than that of [Pmim]BF 4 ‐HTO/TiO 2 (0.0262 min −1 ), [Emim]Br‐HTO/TiO 2 (0.0256 min −1 ), No IL‐HTO/TiO 2 (0.0245 min −1 ), CM‐TiO 2 (0.0132 min −1 ) and Blank samples (0.0004 min −1 ), respectively. Compared with CM‐TiO 2 and other HTO/TiO 2 samples, the Bmim‐HTO/TiO 2 composite featuring cuboid anatase TiO 2 nanocrystals with co‐exposed [111]‐facets and {101} facets, exhibited superior photocatalytic activity in degrading methylene blue (MB) under ultraviolet light irradiation. This exceptional performance can be attributed to its cooperative effects, including a larger specific surface area, the co‐exposure of [111]‐ and {101} facets, a suitable heterojunction structure, and the most efficient charge carrier separation. This work introduces a hydrothermal soft chemical process for preparing HTO/TiO 2 composite with controllable morphology and co‐exposed reactive facets, which holds promise for practical applications in removing organic pollutants from printing and dyeing wastewater.