Low temperature gel-combustion synthesis of porous nanostructure LaFeO3 with enhanced visible-light photocatalytic activity in reduction of Cr(VI)

Abstract

LaFeO3 was synthesized via a simple gel-combustion method at the calcination temperatures of 200–400°C. The X-ray diffraction characterization indicated that the products synthesized at 200–400°C were all pure perovskite phase LaFeO3. The scanning electron microscopy images revealed that the LaFeO3 synthesized at 200°C had a porous nanostructure, but became a solid nanostructure at 400°C. The nitrogen adsorption measurements suggested that the specific surface area of LaFeO3 increased with the lowering of the calcination temperature. The UV–vis diffuse reflection spectra showed that the LaFeO3 synthesized at 200°C exhibited the strongest absorption of visible-light. The photocatalytic experiments demonstrated that as the calcination temperature was lowered, the resultant LaFeO3 exhibited obviously enhanced photocatalytic activity in reduction of Cr(VI) in aqueous solution under visible-light (wavelength longer than 420nm) irradiation. This work can enrich our knowledge on the synthesis and photoabsorption properties of porous nanostructure LaFeO3, and contribute to the application of LaFeO3 nanomaterials in treating the wastewaters contaminated by highly toxic and intractable Cr(VI).