Abstract:Iron(iii) titanates are composed of earth-abundant elements and are attracting rapidly growing interest as highly promising candidates for solar-energy as well as optoelectronics applications.
“…Open Sci. 7: 200708 Fe 2 TiO 5 [34,35], though many authors have experimentally and by DFT calculations obtained higher values for the indirect band gap in the range 2-2.2 eV [24,27,[36][37][38]. Considering these results, as synthesized Fe 2 TiO 5 nanoparticles could have the potential for the degradation of different pollutants in the visible-light region.…”
The aim of this work was to synthesize semiconducting oxide nanoparticles using a simple method with low production cost to be applied in natural sunlight for photocatalytic degradation of pollutants in waste water. Iron titanate (Fe
2
TiO
5
) nanoparticles with an orthorhombic structure were successfully synthesized using a modified sol–gel method and calcination at 750°C. The as-prepared Fe
2
TiO
5
nanoparticles exhibited a moderate specific surface area. The mesoporous Fe
2
TiO
5
nanoparticles possessed strong absorption in the visible-light region and the band gap was estimated to be around 2.16 eV. The photocatalytic activity was evaluated by the degradation of methylene blue under natural sunlight. The effect of parameters such as the amount of catalyst, initial concentration of the dye and pH of the dye solution on the removal efficiency of methylene blue was investigated. Fe
2
TiO
5
showed high degradation efficiency in a strong alkaline medium that can be the result of the facilitated formation of OH radicals due to an increased concentration of hydroxyl ions.
“…Open Sci. 7: 200708 Fe 2 TiO 5 [34,35], though many authors have experimentally and by DFT calculations obtained higher values for the indirect band gap in the range 2-2.2 eV [24,27,[36][37][38]. Considering these results, as synthesized Fe 2 TiO 5 nanoparticles could have the potential for the degradation of different pollutants in the visible-light region.…”
The aim of this work was to synthesize semiconducting oxide nanoparticles using a simple method with low production cost to be applied in natural sunlight for photocatalytic degradation of pollutants in waste water. Iron titanate (Fe
2
TiO
5
) nanoparticles with an orthorhombic structure were successfully synthesized using a modified sol–gel method and calcination at 750°C. The as-prepared Fe
2
TiO
5
nanoparticles exhibited a moderate specific surface area. The mesoporous Fe
2
TiO
5
nanoparticles possessed strong absorption in the visible-light region and the band gap was estimated to be around 2.16 eV. The photocatalytic activity was evaluated by the degradation of methylene blue under natural sunlight. The effect of parameters such as the amount of catalyst, initial concentration of the dye and pH of the dye solution on the removal efficiency of methylene blue was investigated. Fe
2
TiO
5
showed high degradation efficiency in a strong alkaline medium that can be the result of the facilitated formation of OH radicals due to an increased concentration of hydroxyl ions.
“…47 For films grown under an oxygen atmosphere, Eg indirect amounts to ~ 2.11 eV and Eg direct to ~ 2.3 eV which closely matches previous reports. 18,36 Films grown in vacuum showed lower band gaps (indirect -2.04 eV and direct -2.18 eV) which could point out the presence of oxygen deficiencies in the lattice, still unchanged after the post-deposition annealing in air. 48 The detailed fitting of Fe p / peak, shown as violet peaks numbered to , were used to quantify the Fe:Ti ratios on the surface or near-surface region of the films.…”
Pulsed laser deposition (PLD) is an appealing technique to fabricate thin films with specific film orientation, stoichiometry, and morphology through tuning of experimental parameters. Here, we present Fe2TiO5, one of the promising photoanode materials, grown on fluorine-doped tin oxide (FTO) substrates through PLD. The structural and morphological properties of Fe 2 TiO 5 films, grown at room temperature and under varying oxygen pressure were studied. After deposition, all films were annealed in air at 650°C for 2 hours to complete phase crystallization. Films grown under vacuum (1.1 x 10 -6 mbar) were compact, dense, and had the anticipated stoichiometry, but lacked the long-range order expected for a crystalline phase in Xray diffraction. In contrast, using an oxygen pressure (p O 2 ) of around 9.7 x 10 -2 mbar during growth resulted in nanoporous, crystalline, and near-stoichiometric films of the orthorhombic Fe 2 TiO 5 pseudobrookite phase. These films demonstrated a photocurrent density of around 0.16 mA/cm 2 at 1.23 V vs RHE and a negative shift in onset potential by 150 mV under backside illumination as compared to the films grown under vacuum. Notably, these films exhibited a preferred (101) orientation of the pseudobrookite grains.This study proposes a viable strategy to fabricate pure phase and anisotropic Fe 2 TiO 5 photoanodes on FTO through PLD. This will pave a way to synthesis of other complex metal oxide photoelectrodes with precise control over critical properties like crystallinity, stoichiometry, and porosity that is imperative for their application in solar energy conversion.
“…An additional XRD study of 20Fe-900 sample shows the formation of Fe-containing pseudobrookite Fe2TiO5 phase [35] with a content of about 29 mol. % and transitions of amorphous anatase to monoclinic titania (space group symmetry С12/m1) typically obtained by thermal decomposition of layered H2Ti3O7 titanites [36].…”
Ultrafine Fe-doped TiO2 (Fe content of 0, 0.5, 2, 5, 10, and 20 wt. %) was prepared using two-stage TiCl4 and FeCl36H2O hydrolysis at final pH 3.5. The effect of the Fe ion weight concentration on the phase composition and morphology was investigated using XRD, FTIR, Mossbauer spectroscopy, thermal analysis, and low-temperature nitrogen adsorption. Increasing the content of Fe 3+ ions in the range of 0-10 wt. % causes an increase in the amount of the anatase phase from 0 to 85-90 %. The average size of anatase particles decreases from 31 nm for a Fe content of 0.5 wt. % to about 4 nm for a Fe content of 10 wt. %. The material synthesized at an Fe ion concentration of 20 wt. % is amorphous (XRD data) without any magnetically ordered iron-containing phase. The Mossbauer spectra of all Fe-doped TiO2 samples consist of doublets only, with isomer shift values of 0.55-0.57 mm/s corresponding to Fe 3+ in a high-spin state in octahedral coordination, so isomorphic substitution of Ti 4+ ions for Fe 3+ is highly probable. Annealing of Fe-doped TiO2 sample with a maximum doping degree (20 wt. %) at 900 C leads to the formation of the Fe2TiO5 pseudobrookite phase and the transition of amorphous anatase to monoclinic titania (space group symmetry С12/m1). The BET specific surface area values of Fe-doped titania increase linearly from 70 to 350 m 2 /g with increasing iron content from 0 to 5 wt. %. Further increase in the iron content does not affect the BET surface area. The growth of oxygen vacancies concentration with increasing Fe 3+ content was observed by FTIR that corresponds to the reduction of the rutile lattice constant. The anatase-rutile transition temperature (thermal analysis data) is the highest (about 575 C) for the material with the maximum Fe ion content. Photocatalytic activity of Fe-doped TiO2 samples in reaction of methylene blue degradation increases with an increase in the Fe content and correlates with the anatase phase relative concentration. The reaction rate increases from about 0.008 to 0.028 min -1 , while the reaction rate for commercial photocatalyst Degussa P25 under the same experimental conditions is about 0.029 min -1 .
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