In Situ Grown TiO₂ Nanospindles Facilitate the Formation of Holey Reduced Graphene Oxide by Photodegradation

Titanium dioxide (TiO₂) nanostructures and TiO₂/graphene nanocomposites are intensively studied materials for energy conversion, energy storage, and organic contaminant photodegradation. However, for TiO₂/graphene composites, impermeability across the graphitic basal plane for electrolytes, metal ions, and gas molecules hinders their practical applications. Herein we report a simple, environmentally friendly synthetic route for mesoporous anatase TiO₂ nanospindles, and successfully apply this method to obtain in situ grown TiO₂ nanospindles/graphene oxide composite. After a thermal reduction at 400 °C, holes are created in the reduced graphene oxide (RGO) sheets through a photocatalytic oxidation mechanism. The formation of holes in RGO is promoted by photogenerated hydroxyl radicals that oxidize and subsequently decarboxylate the graphitic surface of RGO. The proposed mechanism was supported by photocatalytic electrochemical properties of the nanomaterials. The resulting TiO₂/holey RGO composites may overcome the original impermeability of graphene sheets and find applications in catalysis, energy conversion/storage devices, and sensors.