Kinetic reconstruction of TiO2 surfaces as visible-light-active crystalline phases with high photocatalytic performance

Abstract

Modulation of the TiO₂ structure to achieve efficient photocatalytic usage of solar light is still a challenging issue. Here we report that simple bombardment of anatase TiO₂ nanocrystals by hot molecules can alter its phase transformation kinetics and lead to the reconstruction of the resulting rutile surfaces into a metastable TiO₂ crystalline structure. Moreover, the metastable surface crystalline phase is able to harvest visible light up to 480 nm, and exhibits good properties for photocurrent generation. Photocatalysis tests show that upon irradiation by visible light (λ > 420 nm), the surface-reconstructed TiO₂ crystals display excellent and stable photocatalytic activity for hydrogen production from aqueous ethanol solution, with a hydrogen production rate of 302 μmol g⁻¹ h⁻¹. This finding might bring a new approach to kinetically tune the structure of TiO₂ or other semiconductor crystals in order to modulate their properties.