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 SnO2-TiO2 core-shell nanowires. SnO2 nanowires were grown by decomposition of Sn((OBu)-Bu-t)(4) precursor on Au-coated Al2O3 substrates followed by the growth of a TiO2 overlayer by the CVD of Ti((OPr)-Pr-i)(4). Structural characterization of SnO2-TiO2 heterostructures by X-ray diffraction and high-resolution TEM revealed the formation of mixed SnxTi1-xO2 compositions (x = 0.857-1.0) at the SnO2-TiO2 phase boundaries, where x depended on the annealing temperatures. The observed oriented attachment of TiO2 nanoclusters on single crystal SnO2 core was possibly due to low lattice mismatch. The photocatalytic studies suggested an enhanced activity in SnO2-TiO2 heterostructures due to higher surface area and change in the electronic structures caused by Sn4+ doping in TiO2.