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.