Synthesis of uniform ordered mesoporous TiO₂ microspheres with controllable phase junctions for efficient solar water splitting

Abstract

As a benchmark photocatalyst, commercial P25-TiO₂ has been widely used for various photocatalytic applications. However, the low surface area and poorly porous structure greatly limit its performance. Herein, uniform ordered mesoporous TiO₂ microspheres (denoted as Meso-TiO₂-<i>X</i>; <i>X</i> represents the rutile percentage in the resultant microspheres) with controllable anatase/rutile phase junctions and radially oriented mesochannels are synthesized by a coordination-mediated self-assembly approach. The anatase/rutile ratio in the resultant microspheres can be facilely adjusted as desired (rutile percentage: 0-100) by changing the concentration of hydrochloric acid. As a typical one, the as-prepared Meso-TiO₂-25 microspheres have a similar anatase/rutile ratio to commercial P25. But the surface area (78.6 m² g^-1) and pore volume (0.39 cm³ g^-1) of the resultant microspheres are larger than those of commercial P25. When used as the photocatalyst for H₂ generation, the Meso-TiO₂-25 delivers high solar-driven H₂ evolution rates under air mass 1.5 global (AM 1.5 G) and visible-light (<i>λ</i> > 400 nm), respectively, which are significantly larger than those of commercial P25. This coordination-mediated self-assembly method paves a new way toward the design and synthesis of high performance mesoporous photocatalysts.