Synthesis of Porous Crystalline Doped Titania Photocatalysts Using Modified Precursor Strategy

We propose a new strategy for the synthesis of porous crystalline doped titania materialsdubbed the modified precursor strategy. The modified precursors are prepared by reacting generic titania precursors with organic acids in order to introduce “carbonizable” groups into the precursor’s structure, so that carbon–titania composites can form upon carbonization. The resulting carbon framework serves as a scaffold for TiO₂ and supports the structure during crystallization. Afterward, removal of the carbon scaffold through calcination results in titania with a well-developed structure and high crystallinity. The titanias synthesized according to this strategy, using common organic acids as the modifiers, have specific surface areas reaching 100 m² g^–1 and total pore volumes exceeding 0.20 cm³ g^–1, even after crystallization at temperatures from 500 to 1000 °C. The materials possess high crystallinity and tunable phase composition, and some show visible light absorption and significantly narrowed band gaps (2.3–2.4 eV). Photocatalytic degradation of methylene blue proved that these photocatalysts are active under visible light. All tested titanias show an excellent photocatalytic performance due to the combined effects of the well-developed structure, high crystallinity, and narrow band gap. This strategy can easily be adopted for the preparation of other porous crystalline materials