TiO2 nanowires doped with different amounts of Ni2+ ions (from 0 to 18 mol%) were synthesized by hydrothermal technique. The samples were characterized by X-ray diffraction (XRD) and Raman spectroscopy, field emission scanning electron microscopy (FESEM), and diffuse reflection spectroscopy. The XRD analysis showed that the doped samples exhibit anatase single phase. The lattice parameters remain unchanged, independent on Ni2+ content. | VNU Journal of Science: Mathematics – Physics, Vol. 32, No. 3 (2016) 34-40 Synthesis and Characterization of Ni2+-doped TiO2 Nanowires Trinh Thi Loan*, Vu Hoang Huong, Tran Thi Dung, Nguyen Ngoc Long Faculty of Physics, VNU University of Science, 334 Nguyen Trai, Thanh Xuan, Hanoi, Vietnam Received 19 September 2016 Revised 28 September 2016; Accepted 30 September 2016 Abstract: TiO2 nanowires doped with different amounts of Ni2+ ions (from 0 to 18 mol%) were synthesized by hydrothermal technique. The samples were characterized by X-ray diffraction (XRD) and Raman spectroscopy, field emission scanning electron microscopy (FESEM), and diffuse reflection spectroscopy. The XRD analysis showed that the doped samples exhibit anatase single phase. The lattice parameters remain unchanged, independent on Ni2+ content. Diameter of TiO2 nanowires increased significantly with increasing concentrations of Ni 2+. The investigated results indicate that a greater portion of the Ni2+ ions are well-incorporated into the anatase TiO2 lattice. Indirect and direct band gap energies of Ni2+-doped TiO2 with different doping concentration were found to be in the range from to eV and to eV, respectively. Keywords: TiO2:Ni2+ nanowires, hydrothermal, diffuse reflection, band gap energy. 1. Introduction In recent few decades, titanium dioxide (TiO2) is extensively studied by different research centers throughout the world due to its wide applications in such areas as photocatalysis [1], solar energy conversion [2], gas sensing [3], and many others [4, 5]. However, TiO2 has limited applications under visible light irradiation because of its poor light absorption ability and low charge separation efficiency under normal reaction conditions. This is due to its wide band gap [6, 7]. One effort to improve the light absorption of TiO2 for efficient utilization of the solar energy spectrum is the doping with transition metals, which inserts a new band into the original band .
