From Nanorods to Atomically Thin Wires of Anatase TiO2: Nonhydrolytic Synthesis and Characterization

A nonhydrolytic two-step chemical process has been developed to synthesize ultrathin, nearly monodisperse TiO2 (anatase) wires with tunable diameters of 5 nm to approximately 4 angstrom, reaching the atomic length scale. The high-quality anatase titania atomically thin wires can be doped and stabilized with nitrogen species by introducing suitable nitrogen-containing molecules. The ultrathin wires, particularly the atomically thin wires, as well as the precursor, have been thoroughly characterized by an extensive series of structural, spectroscopic, and other techniques. Possible formation mechanisms for the rods and the wires are proposed on the basis of experimental results obtained under varying reaction conditions. Also demonstrated are the pronounced effects of size and N-doping on the electronic, optical, and phononic properties of the anatase titania wires in the smallest size regime.