Mixed-Phase MOF-Derived Titanium Dioxide for Photocatalytic Hydrogen Evolution: The Impact of the Templated Morphology

Abstract

Herein, we explored a simple metal–organic framework (MOF)-mediated synthesis for the controlled preparation of pure and mixed-phase titania (TiO2) nanoparticles. Scanning electron microscopy images revealed that the MOF-derived TiO2 retains the MOF crystal shape, and through powder X-ray diffraction and X-ray photoelectron spectroscopy, it is demonstrated that the crystal template is composed of nanosized TiO2 rutile and anatase particles. The presence of both TiO2 rutile and anatase phases in the crystal template enhances the interactions between them, thus suppressing the electron–hole recombination. This has an impact on the photocatalytic reduction of water because templated MOF-derived TiO2 outperforms the commercial (P25 Degussa), titanium isopropoxide-derived and nontemplated MOF-derived TiO2. Our study demonstrates that the morphologically induced high charge separation efficiency afforded by using MOF crystals as precursors can lead to the generation of catalytically more active materials that can challenge existing photocatalysts in the field of hydrogen generation.