Linker-Free Modification of TiO₂ Nanorods with PbSe Nanocrystals

We report on a colloidal synthesis of PbSe/TiO 2 heterostructures, comprising small-diameter PbSe nanocrystals epitaxially grown onto the surface of TiO 2 nanorods. The deposition of lead selenide onto prefabricated TiO 2 nanocrystals proceeds via formation of a thin PbSe shell that subsequently breaks into sub-2-nm islands. Additional precursor injections are then used to increase the size of PbSe nanocrystals up to 5 nm. In the case of small-size PbSe, a 2.1-ns transfer of photoinduced carriers into TiO 2 domain was evidenced through quenching of the PbSe band gap emission. Overall, the present synthesis demonstrates a colloidal approach to all-inorganic modification of TiO 2 surfaces with semiconductor nanocrystals, which provides a viable alternative to a more common supramolecular assembly of nanocrystal-oxide composites.