High Activity Ti3+-Modified Brookite TiO2/Graphene Nanocomposites with Specific Facets Exposed for Water Splitting

Brookite TiO2 exhibits promising photocatalytic activity in photoreduction; however, it is least known due to poor stability. We have synthesized Ti3+-modified brookite TiO2/graphene nanocomposites with specific facets exposed successfully. They show highly improved photoreduction activity for water splitting into H-2 with excellent stability. The well-crystallized brookite TiO2 nanorods are surrounded by four reductive (211) facets with high conduction band potential and growth along the [001] direction, indicating that they have high photoreduction ability because more reductive electrons will be excited. By combining spectroscopic techniques and electrochemical analysis methods, the outstanding activity could be linked with the synergistic effects of highly exposed (211) facets, Ti3+ defects, and graphene. Their formation mechanism and the effects in the enhanced photoreduction activity have been discussed in detail. In addition to promoting the separation of photogenerated e(-)-h(+) pairs effectively, the midgap state was introduced and the absorption ability was improved.