Perovskite-type LaFeO3: Photoelectrochemical Properties and Photocatalytic Degradation of Organic Pollutants Under Visible Light Irradiation

Abstract

Perovskite-type oxides lanthanum ferrite (LaFeO3) photocatalysts were successfully prepared by a facile and cost-effective sol-gel method using La(NO)3 and Fe(NO)3 as metal ion precursors and citric acid as a complexing agent at different calcination temperatures. The properties of the resulting LaFeO3 samples were characterized by powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDXS), UV-Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (IR), transmission electron microscopy (TEM), N2 adsorption/desorption and photoelectrochemical tests. The photoactivity of the LaFeO3 samples was tested by monitoring the photocatalytic degradation of Rhodamine B (RhB) and 4-chlorophenol (4-CP) under visible light irradiation, the highest photocatalytic activity was found for LaFeO3 calcined at 700 °C, which attributed to the relatively highest surface area (10.6 m2/g). In addition, it was found from trapping experiments that the reactive species for degradation were superoxide radical ions (O2−) and holes (h+). Photocurrent measurements and electrochemical impedance spectroscopy (EIS) proved the higher photo-induced charge carrier transfer and separation efficiency of the LaFeO3 sample calcined at 700 °C compared to that that calcined at 900 °C. Band positions of LaFeO3 were estimated using the Mott-Schottky plots, which showed that H2 evolution was not likely.