Acid-regulated hydrolysis and condensation of titanium cation toward controllable synthesis of multiphase mesoporous TiO2 for effectively enhance photocatalytic H2 evolution

Abstract

Titanium dioxide (TiO2) polymorphs photocatalysts containing two or more crystal phases have customarily been synthesized at high temperature using complicated procedures or expensive equipment, accompanied by the formation of by-products. Therefore, here, we propose an effective acid-regulated hydrolysis and condensation of titanium cation strategy to directly synthesize mesoporous TiO2 with controllable phase junctions. In the method, poly dimethyl diallyl ammonium chloride (PDADMAC) is used as the structure directing agent to produce mesostructure, and hydrochloric acid (HCl) is used as the acid regulator and coordination agent to adjust the hydrolysis and condensation modes of Ti4+, thereby controlling the crystal structure and phase junctions of synthesized mesoporous TiO2 polymorphs. Furthermore, since the heterophase junctions and mesostructure effectively improve the separation and transfer of photo-generated electron-holes, the obtained R74B26 with unique brookite and rutile phase junctions owns the highest photocatalytic activity among all obtained samples, the evolution rate of H2 is 8.98 mmol h‐1−1 g−1. This work will open up new perspectives toward the synthesis of mesoporous polycrystalline material for various potential applications.