SnO2–TiO2 Core–Shell Nanowire Structures: Investigations on Solid State Reactivity and Photocatalytic Behavior

Two-step chemical vapor deposition (CVD) in combination with metal-catalyzed vapor–liquid–solid (VLS) growth mechanism was used as a new approach to synthesize and modify the morphology of SnO 2 –TiO 2 core–shell nanowires. SnO 2 nanowires were grown by decomposition of Sn(O t Bu) 4 precursor on Au-coated Al 2 O 3 substrates followed by the growth of a TiO 2 overlayer by the CVD of Ti(O i Pr) 4 . Structural characterization of SnO 2 –TiO 2 heterostructures by X-ray diffraction and high-resolution TEM revealed the formation of mixed Sn x Ti 1– x O 2 compositions ( x = 0.857–1.0) at the SnO 2 –TiO 2 phase boundaries, where x depended on the annealing temperatures. The observed oriented attachment of TiO 2 nanoclusters on single crystal SnO 2 core was possibly due to low lattice mismatch. The photocatalytic studies suggested an enhanced activity in SnO 2 –TiO 2 heterostructures due to higher surface area and change in the electronic structures caused by Sn 4+ doping in TiO 2 .