Atmospheric pressure chemical vapour deposition of boron doped titanium dioxide for photocatalytic water reduction and oxidation.

Boron-doped titanium dioxide (B-TiO2) films were deposited by atmospheric pressure chemical vapour deposition of titanium(iv) chloride, ethyl acetate and tri-isopropyl borate on steel and fluorine-doped-tin oxide substrates at 500, 550 and 600 °C, respectively. The films were characterised using powder X-ray diffraction (PXRD), which showed anatase phase TiO2 at lower deposition temperatures (500 and 550 °C) and rutile at higher deposition temperatures (600 °C). X-ray photoelectron spectroscopy (XPS) showed a dopant level of 0.9 at% B in an O-substitutional position. The ability of the films to reduce water was tested in a sacrificial system using 365 nm UV light with an irradiance of 2 mW cm(-2). Hydrogen production rates of B-TiO2 at 24 µL cm(-2) h(-1) far exceeded undoped TiO2 at 2.6 µL cm(-2) h(-1). The B-TiO2 samples were also shown to be active for water oxidation in a sacrificial solution. Photocurrent density tests also revealed that B-doped samples performed better, with an earlier onset of photocurrent.

Mechanistic investigation of the growth of Fe1-xCoxSi (0 ≤ x ≤ 1) and Fe5(Si1-yGey)3 (0 ≤ y ≤ 0.33) ternary alloy nanowires.

We present the chemical vapor deposition (CVD) reactions of the single source precursor Fe(SiCl(3))(2)(CO)(4) over Si, Ge, CoSi(2)/Si, and CoSi/Si substrates to explore the growth and doping processes of silicide nanowires (NWs). Careful investigation of the composition and morphology of the NW products and the intruded silicide films from which they nucleate revealed that the group IV elements (Si, Ge) in the NW products originate from both the precursor and the substrate, while the metal elements incorporated into the NWs (Fe, Co) originate from vapor phase precursor delivery. The use of a Ge growth substrate enabled the successful synthesis of Fe(5)Si(2)Ge NWs, the first report of a metal silicide-germanide alloy NW. Further, investigation of the pyrolysis of the CoSiCl(3)(CO)(4) precursor revealed independent delivery of Co and Si species during CVD reactions. This understanding enabled a new, more robust two-precursor synthetic route to Fe(1-x)Co(x)Si alloy NWs using Fe(SiCl(3))(2)(CO)(4) and CoCl(2).