Titania Tube-in-Tube Scaffolds with Multilength-Scale Structural Hierarchy and Structure-Enhanced Functional Performance

Hierarchical structuration has proven to be effective in optimizing the functional performance of nanomaterials. Herein, we report for the first time the evolution of a titania tube-in-tube scaffolding architecture with multilength-scale structural hierarchy (TITS TiO2) and structure-enhanced functional performance. The nanoengineering was accomplished by a precursor scaffolding-concurrent epitaxial growth approach using bacterial cellulose (BC) as a bioscaffold. The BC@SiO2@TiO2 precursor scaffold with a sandwiching SiO2 layer plays an essential role in the formation of the tube-in-tube geometry. TITS TiO2 exhibits significantly superior photocatalytic activity to Degussa P25. It shows great UV light absorption ability and high specific surface area, which we believe are responsible for its superior photocatalytic activity. The monolithic nature of TITS TiO2 makes photocatalyst separation and recovery possible. We show that TiO2 nanocrystals can be used as a building block for the organization of complex inorganic nanomaterials with multilength-scale structural hierarchy using a bioscaffold with desired structural features: monolith (millimeter and above), macropore (micrometer), and nanotube/nanopore (nanometer), offering a versatile route for the design of advanced hierarchical nanomaterials.