One-step hydrothermal synthesis of Sn-doped α-Fe2O3 nanoparticles for enhanced photocatalytic degradation of Congo red

We report on the synthesis of Sn-doped hematite nanoparticles (Sn-alpha-Fe2O3 NPs) by the hydrothermal method. The prepared Sn-alpha-Fe2O3 NPs had a highly pure and well crystalline rhombohedral phase with an average particle size of 41.4 nm. The optical properties of as-synthesized alpha-Fe2O3 NPs show a higher bandgap energy (2.40-2.57 eV) than that of pure bulk alpha-Fe2O3 (2.1 eV). By doping Sn into alpha-Fe2O3 NPs, the Sn-doped hematite was observed a redshift toward a long wavelength with increasing Sn concentration from 0% to 4.0%. The photocatalytic activity of Sn-doped alpha-Fe2O3 NPs was evaluated by Congo red (CR) dye degradation. The degradation efficiency of CR dye using Sn-alpha-Fe2O3 NPs catalyst is higher than that of pure alpha-Fe2O3 NPs. The highest degradation efficiency of CR dye was 97.8% using 2.5% Sn-doped alpha-Fe2O3 NPs catalyst under visible-light irradiation. These results suggest that the synthesized Sn-doped alpha-Fe2O3 nanoparticles might be a suitable approach to develop a photocatalytic degradation of toxic inorganic dye in wastewater.