Synthesis of large surface area LaFeO3 nanoparticles by SBA-16 template method as high active visible photocatalysts

Nanosized LaFeO₃ with large specific surface area has been successfully synthesized by an impregnation process, with mesoporous silica SBA-16 as hard template and corresponding metal nitrates as La and Fe resources, and the resulting LaFeO₃ is also characterized by thermogravimetry–differential thermal analysis (TG–DTA), X-ray diffraction (XRD), N₂ adsorption–desorptions, Brunauer Emmett Teller (BET) technique, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–visible diffuse reflection spectrum (UV–Vis DRS), and surface photovoltage spectroscopy (SPS). It is found that, compared with that prepared by the conventional citrate method, the as-prepared LaFeO₃ with 20-50 nm particle size has remarkable large specific surface area, even still with the surface area as large as about 85 m² g⁻¹ after calcination at 800 °C, which is attributed to its mesoporous structure as well as the small particle size. During the photocatalytic degradation of Rhodamine B solution under visible irradiation, all the LaFeO₃ samples obtained are superior to P25 TiO₂, and the activity becomes high with increasing calcination temperature. It is revealed that the excellent photocatalytic performance is mainly ascribed to the large surface area and high photogenerated charge separation rate.