Fe-doped nanostructured titanates synthesized in a single step route

Journal Article · Thu Jan 15 04:00:00 UTC 2015 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2014.11.029· OSTI ID:22476014

Costa, A. M.L.M., ^[1]; Marinkovic, B. A. ^[1]; Suguihiro, N. M. ^[2]; Smith, D. J. ^[3]; Paciornik, S. ^[1]

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1. Departamento de Engenharia de Materiais, Pontifícia Universidade Católica do Rio de Janeiro, 22451-900 Rio de Janeiro, RJ (Brazil)
2. Centro Brasileiro de Pesquisas Físicas, 22290-180 Rio de Janeiro, RJ (Brazil)
3. Department of Physics, Arizona State University, Tempe, AZ 85287 (United States)

In this research nanostructured titanates, containing iron in the structure, were obtained through a single-step alkaline hydrothermal route aiming at reduction of band-gap energy. In the process, a Fe–Ti rich Brazilian mineral sand was mixed with 10 M of NaOH and then submitted to isothermal treatments at temperatures ranging from 110 to 190 °C in an autoclave. The as-obtained products were water-washed and then characterized by transmission electron and scanning transmission electron microscopies, X-ray photoelectron, Mössbauer and diffuse reflectance spectroscopies. Transmission electron microscopy analyses showed a morphological dependence of the product as a function of the temperature, i.e., titanate nanosheets were predominantly formed at lower temperatures (110 °C–150 °C), while nanoribbons, with some nanosheets and nanoparticles, were the main products at higher temperatures (> 150 °C). Using energy dispersive X-ray it was determined that iron was incorporated into nanosheets. On the other hand, the as-obtained nanoribbons were Fe-free, while iron was principally associated with nanoparticles attached to the nanoribbons. By means of X-ray photoelectron and Mössbauer spectroscopies, it was elucidated that iron adopted Fe{sup 3} {sup +} form in the as-prepared nanosheets, occupying octahedral sites inside the titanate lepidocrocite-like structure. Diffuse reflectance spectroscopy showed a change of absorption pattern from nanosheets to nanoribbon/nanoparticle assembly: nanosheets exhibited high absorption from ultraviolet up to the visible light range, while the nanoribbon/nanoparticle assembly demonstrated a drop in absorption in the visible light range. These results suggest that Fe{sup 3} {sup +} incorporation inside the titanate structure is responsible for enhancing the visible light absorption, making these nanosheets potentially suitable for applications in photoinduced processes. - Highlights: • Mineral sand has been used as the precursor for the synthesis of nanotitanates. • Fe-doped nanotitanates have been prepared in a single step wet chemistry route. • The morphology of the nanometric titanates is a function of the temperature. • Mössbauer spectroscopy reveals Fe{sup 3} {sup +} in octahedral sites inside nanosheets. • The Fe incorporation in nanosheets improved the visible light absorption.

• OSTI ID: 22476014
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Vol. 99; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ABSORPTION
DOPED MATERIALS
HYDROTHERMAL SYNTHESIS
IRON ADDITIONS
MINERALS
NANOMATERIALS
NANOPARTICLES
NANOSTRUCTURES
PRECURSOR
REDUCTION
SAND
SODIUM HYDROXIDES
SPECTROSCOPY
TITANATES
TRANSMISSION
TRANSMISSION ELECTRON MICROSCOPY
ULTRAVIOLET RADIATION
VISIBLE RADIATION
WATER