Synthesis of Homogeneous Manganese-Doped Titanium Oxide Nanotubes from Titanate Precursors

Abstract

We report a novel synthesis route of homogeneously manganese-doped TiO2 nanotubes in a broad concentration range. The scroll-type trititanate (H2Ti3O7) nanotubes prepared by hydrothermal synthesis were used as precursors. Mn 2+ ions were introduced by an ion exchange method resulting MnxH2−xTi3O7. In a subsequent heat-treatment they were transformed into MnyTi1−yO2 where y = x/(3 + x). The state and the local environment of the Mn 2+ ions in the precursor and final products were studied by Electron Spin Resonance (ESR) technique. It was found that the Mn 2+ ions occupy two positions: the first having an almost perfect cubic symmetry while the other is in a strongly distorted octahedral site. The ratio of the two Mn 2+ sites is independent of the doping level and amounts to 15:85 in MnxH2−xTi3O7 and to 5:95 in MnyTi1−yO2. SQUID magnetometry does not show long-range magnetic order in the homogeneously Mn 2+ -doped nanotubes.

Optically switched magnetism in photovoltaic perovskite CH3NH3(Mn:Pb)I3

“…As expected, Mn substitution gives an easily observable signal. At low concentration, ESR shows well-resolved hyperfine lines indicating the uniform dispersion of Mn 2+ ions24 (Supplementary Fig. 5).…”

“…It should be emphasized that the homogeneous magnetic ordering itself in this insulating photovoltaic perovskite is already a remarkable observation. Such ordering was extensively searched for in homogeneously diluted magnetic semiconductors, and unambiguously observed only in few cases24272829.…”

“…The well-resolved hyperfine also testifies the homogeneous distribution of Mn ions in MAMn:PbI 3 (ref. 24). …”

One-Dimensional Titanium Dioxide Nanomaterials: Nanotubes

“…Hydrothermally grown TiO 2 nanotubes can be doped with various elements including chromium, manganese, cobalt, niobium, vanadium, bismuth, boron, phosphor, gadolinium, platinum, iron, and neodymium 457,458,[460][461][462][464][465][466] . Different co-doped 459,463 and tri-doped 467 TiO 2 nanotubes were also reported.…”

Lignosulfanate-assistant hydrothermal method for synthesis of titanate nanotubes with improved adsorption capacity for metal ions

“…The synthetic methods, formation mechanisms, structures, properties and applications of TNTs have been extensively studied [2][3][4]. Recently, TNTs attracted much more attention in the field of water treatment and were considered as a promising adsorbent for pollutants removal due to their good ion-exchange ability and large surface area.…”