Highly photocatalytic activity of brookite/rutile TiO2 nanocrystals with semi-embedded structure

• High content of brookite (72%) was achieved via a solvothermal approach.
• Tert-butanol was found that can induce the formation of brookite.
• High rate constants of three times higher than commercial DegussaP-25.
• Phase composition, content as well as hybrid crystal structure were analyzed to explore the synergetic effect.
• Semi-embedded structure importantly influences the final activity.

A facile solvothermal approach was used to prepare brookite-type TiO2 nanocrystals with different phase content and structure, accomplished by adjusting the ratio of TiCl4 to t-BuOH. The obtained biphasic brookite/rutile TiO2 nanocrystals showed a high brookite weight content (72%). The photocatalytic degradation of phenol under UV-irradiation was used to determine the synergetic effect from the combination of different phases (e.g., brookite, anatase, and rutile). The biphasic NST-4 composed of brookite and rutile exhibited the highest degradation rates, with rate constants three times higher than commercial Degussa P-25. Detailed analysis found that, besides phase composition and content, the semi-embedded structure was essential to obtain a superior activity of biphasic TiO2 samples.

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