Double layered, one-pot hydrothermal synthesis of M-TiO2 (M = Fe3+, Ni2+, Cu2+ and Co2+) and their application in photocatalysis.

A double layered, one-pot hydrothermal method was adopted in this work to prepare transition metal ions (Fe ³⁺, Ni ²⁺, Cu ²⁺ and Co ²⁺) doped TiO ₂. The morphology and chemical properties of TiO ₂ and the status of metal ions were characterized with XRD, TEM, BET, UV-Vis and XPS analysis. TEM images show that the obtained TiO ₂ was very uniform with an average particle size of 10.4 nm. XPS, TEM and XRD results show that transitional metals were doped onto TiO ₂ in the form of ions. Photocatalytic decomposition of oxalic acid under UV illumination and methylene blue degradation under visible light on these materials were conducted, respectively. The results reveal that Cu ²⁺-TiO ₂ and Co ²⁺-TiO ₂ showed a highest activity under UV and visible light illumination, respectively, and they were both more active than commercial P25 TiO ₂. With this special design of double layers, the hydrolysis of titanium precursor in the system with water can be easily controlled and metal ions are simply doped. This strategy can be further applied to synthesize metal ion doped TiO ₂ using various metal precursors with controllable amounts, and thus lead to better optimization of highly active photocatalyst. [ABSTRACT FROM AUTHOR]