Synthesis of High-Quality Brookite TiO_2 Single-Crystalline Nanosheets with Specific Facets Exposed: Tuning Catalysts from Inert to Highly Reactive

摘要

The brookite phase of TiO_2 is hardly prepared and rarely studied in comparison with the common anatase and rutile phases. In addition, there exist immense controversies over the cognition of the light-induced liveliness of this material. Here, a novel, low-basicity solution chemistry method was first used to prepare homogeneous high-quality brookite TiO_2 single-crystalline nanosheets surrounded with four {210}, two {101}, and two {201} facets. These nanosheets exhibited outstanding activity toward the catalytic degradation of organic contaminants superior even to that of Degussa P25, due to the exposure of high-energy facets and the effective suppression of recombination rates of photo-generated electrons and holes by these facets as the oxidative and reductive sites. In contrast, irregularly faceted phase-pure brookite nanoflowers and nanospindles were inactive in catalytic reactions. These results demonstrate that the photocatalytic activity of brookite TiO_2 is highly dependent upon its exposed facets, which offers a strategy for tuning the catalysts from inert to highly active through tailoring of the morphology and surface structure.