Enabling high solubility of ZnO in TiO2 by nanolamination of atomic layer depositionElectronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06264k

• Main Authors: Su, C.-Y, Wang, C.-C, Hsueh, Y.-C, Gurylev, V, Kei, C.-C, Perng, T.-P
• Format: Article
• Language: English
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c5nr06264k

Zn-doped TiO 2 nanotubes were fabricated by nanolaminated packing of alternating layers of TiO 2 and ZnO by atomic layer deposition (ALD) using a polycarbonate (PC) membrane as a template. With 400 cycles of ALD, the nanotubes with a thickness of 28 nm and an outer diameter of 220 nm were obtained after removing the PC membrane by annealing at 450 °C. The doping concentration of ZnO in TiO 2 depends on the precursor cycle ratio of ZnO to TiO 2 . With the precursor cycle ratio of ZnO : TiO 2 at 0.04, a uniform bulk solubility of ∼8 at% is obtained, and the surface concentration of Zn is even higher, ∼16 at%. From the depth profiles measured by secondary ion mass spectrometry, Zn is uniformly distributed across the thickness, which is further confirmed by analyses of X-ray photoelectron spectroscopy, X-ray diffraction, and Raman spectroscopy. Additionally, from the transmission electron microscopic observation, the highly doped anatase TiO 2 exhibits some regions of severe deformation that results in localized solid-state amorphization. Parallel arrays of Zn-doped TiO 2 nanotubes fabricated via nanolaminated packing of alternating layers of TiO 2 and ZnO by ALD using polycarbonate as a template are presented. A uniform bulk solubility of ∼8 at% was achieved, far beyond the nil solubility predicted by the phase diagram.