Visible-light active nanohybrid TiO₂/carbon photocatalysts with programmed morphology by direct carbonization of block copolymer templates

Nanopatterned TiO₂/carbon hybrid materials with tailored morphologies were produced by spin-coating solutions of amphiphilic poly(styrene-block-ethylene oxide) (PS-b-PEO) and inorganic precursors followed by sequential stabilization and carbonization. This synthetic strategy is based on cooperative sol–gel chemistry and self-assembly of block copolymers (BCPs), as well as on direct carbonization of the structure-directing BCP templates without additional carbon precursors. Thin films and powders consisting of either TiO₂ dots in carbon matrices or carbon dots in TiO₂ matrices as well as their powder type samples were obtained by varying the ratio of TiO₂ sol–gel precursor to PS-b-PEO. X-ray photoelectron spectroscopy (XPS) revealed the formation of Ti–O–C bonds upon carbonization, as a result of additional electronic states in TiO₂. The latter can be considered as the origin of the band narrowing and visible light absorption. The obtained carbon–TiO₂ nanostructures showed pronounced visible-light photocatalytic activity.