Evolution of large area TiS₂-TiO₂ heterostructures and S-doped TiO₂ nano-sheets on titanium foils

We report a novel and facile method to synthesize sulfur-doped titanium oxide sheets and realize TiS₂-TiO₂ heterostructures by means of a sequential sulfurization and oxidation step in a dual-zone chemical vapor deposition furnace. The inclusion of chlorine and argon gases during the growth of such titanium-based compounds plays a critical role in the formation of desired geometries and crystalline structures. These heterostructures possess nano-whisker and nanosheet configurations, controlled by adjusting the growth parameters such as temperature, carrier gas and the sequencing between different steps of the growth. The evolution of these complex heterostructures has been investigated using Raman spectroscopy and EDS characterization. The presence of chlorine gas during the growth results in local TiS₂ formation as well as faceted growth of TiO₂ nanosheets through anatase to rutile phase change prohibition. The electron microscopy (TEM) images and diffraction pattern (SAED) characterization reveal the crystallinity and layered nature of grown structures, further demonstrating the 2D characteristics of S-doped nanosheets. The evolution of TiO₂ on TiS₂ heterostructures has also has been verified using XPS analysis. These highly featured nanostructures are suitable candidates to enhance the photocatalytic behavior of TiO₂ nanostructures.