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

Abstract Highly iron-doped tin dioxide nanoparticles (Sn 1⿿x Fe x O 2 NPs), with x varying from 0 to 0.2, were prepared by simple hydrothermal method. X-ray diffraction (XRD) patterns indicate that Sn 1⿿x Fe x O 2 NPs crystallize in the tetragonal rutile-like structure. High-resolution transmission electron microscopy (HRTEM) observations did not show any modification of the SnO 2 lattice parameters with Fe addition. Mossbauer spectroscopy indicated Sn 4+ substitution by Fe 3+ and Fe 4+ ions. It was found that iron addition induced high tunable band gap of SnO 2 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 SnO 2 host. Finally, the photocatalytic efficiency of Sn 1-x Fe x O 2 NPs was examined for the degradation of rhodamine B in aqueous solution under visible light irradiation. We show that Fe 4+ and Fe 3+ ions play a key role in the improvement of the photocatalytic efficiency.