Gelation-induced controlled synthesis of TiO2 with tunable phase transition for efficient photocatalytic hydrogen evolution

Abstract

Methods for the precise tailoring of heterophase junctions and the micro/nanostructure of high-crystallinity TiO₂ are indispensable for the synthesis of TiO₂-based photocatalytic materials with high activity exposure, accessibility, and stability. However, current strategies suffer from an inability to control phase composition, a need for special equipment, and complexity of precursor composition. Here, a facile gelation-induced phase transition strategy is demonstrated to synthesize TiO₂ with precisely tunable anatase and rutile phases by controlling the coordination mode of Ti⁴⁺ during gelation. The synthesized chestnut-shell A₇₆/R₂₄-TiO₂ has a phase composition similar to commercial P25 and a highly crystalline anatase/rutile phase, an interfacial heterogeneous structure and abundant surface oxygen vacancies. The synergistic effect of the heterogeneous structure junction and surface oxygen vacancies contributes to the charge separation efficiency and photocatalytic activity, endowing it with excellent photocatalytic hydrogen production activity, with or without the addition of a co-catalyst. Overall, this approach provides new insights and inspiration to explore the precise regulation of the phase composition of materials.