The origin of visible light photocatalytic activity of N-doped and weak ferromagnetism of Fe-doped ^TiO ₂ anatase

Abstract

In this paper, we present the experimental result as well as the theoretical calculation of the electronic band structures and the optical absorption spectra for N-doped and Fe-doped TiO 2 anatase. The main purpose is to provide evidence in the viewpoint of visible light photocatalytic activity of N-doped and weak ferromagnetism of Fe-doped in TiO 2 anatase. Accordingly, to evaluate the separate contributions of nitrogen doping and iron doping in anatase, we present the results of spin-polarized density functional theory (DFT) calculations that have been used to calculate the electronic band structures and optical absorption spectra that arise for a range of concentrations of (i) substitutional nitrogen and (ii) substitutional iron in anatase TiO 2. Our results show that absorption in the visible range is mainly due to nitrogen states located above the valence bands, whereas weak ferromagnetism of Fe-doped in TiO 2 anatase is mainly caused by spin polarization. These results have important implications for the understanding and further development of photocatalytic materials that are active under visible light. These findings agree favorably with our own experimental data and enable conclusions to be drawn about the nature of the practical catalyst in N-doped and the ferromagnetic origin in Fe-doped TiO 2 anatase.

C-, N-, S-, and F-Doped Anatase TiO2 (101) with Oxygen Vacancies: Photocatalysts Active in the Visible Region

“…On the surface, there is a reduction of the energy bandgap to 2.30 eV (GGAU), whereas the reported experimental value is 2.5 eV [67]. [68]; our calculations also reproduced this result for the N-doped anatase surface and bulk.…”

Visible light responsive titania-based nanostructures for photocatalytic, photovoltaic and photoelectrochemical applications

“…Although this method is expensive and could not be used for widespread applications in practice, it is extremely useful for the fundamental experimental studies on the electronic structures of the related nanophotocatalysts as well as on the principal physical and chemical phenomena and processes in these nanomaterials. Modification of titania nanomaterials by doping transition metals to them was also performed in recent works [98][99][100][101][102][103][104]. Titania-based nanomaterials co-doped by two transition metals Cr and Sb were prepared and investigated in [105][106][107].…”

Effects of structural, optical and ferromagnetic states on the photocatalytic activities of Sn–TiO2 nanocrystals

“…18 The RTFM nanocomposites were found to show better photocatalytic performance instead of diamagnetic commercially available photocatalysts under visible light irradiation. 17,19 In order to take high activity of the coupled, 19 doped or co-doped 20 semiconductor nanocomposites, the concept of magnetic photocatalysts shows better charge carrier separation function. Hence, development of photocatalyst possessing ferromagnetic property in tune with visible-light activity has become an important topic in the photocatalysis research today.…”