Iron addition induced tunable band gap and tetravalent Fe ion in hydrothermally prepared SnO2 nanocrystals: Application in photocatalysis

Highly iron-doped tin dioxide nanoparticles (Sn1-xFexO2 NPs), with x varying from 0 to 0.2, were prepared by simple hydrothermal method. X-ray diffraction (XRD) patterns indicate that Sn1-xFexO2 NPs crystallize in the tetragonal rutile-like structure. High-resolution transmission electron microscopy (HRTEM) observations did not show any modification of the SnO2 lattice parameters with Fe addition. Mossbauer spectroscopy indicated Sn4+ substitution by Fe3+ and Fe' ions. It was found that iron addition induced high tunable band gap of SnO2 NPs. Photoluminescence (PL) spectra evidenced an improvement of SnO2 crystallinity after Fe introduction. All the results are consistent with the fact that Fe is strongly soluble in SnO2 host. Finally, the photocatalytic efficiency of Sn1-xFexO2 NPs was examined for the degradation of rhodamine B in aqueous solution under visible light irradiation. We show that Fe4+ and Fe3+ ions play a key role in the improvement of the photocatalytic efficiency. (C) 2016 Elsevier Ltd. All rights reserved.