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.
Highlights
Semiconductor-based catalysis is a green technology, which gained considerable attention owing to its potential environmental applications, such as wastewater treatment, air purification and degradation of different organic contaminants [1,2,3]
Citric acid assisted sol-gel was chosen as a synthesis route because, in general, it is a suitable method for the synthesis of nanopowders with a well-developed high specific surface area obtained at low calcination temperature and short times without employing expensive sacrificial structure-directing agents or template structures
As for Tijare et al, we attempted hydrogen generation, failed with that and suspected it was based on the Mott-Schottky plots calculating band positions that the conduction band edge of LaFeO3 was too positive than the reduction potential of H2 /H2 O (0 V vs. normal hydrogen electrode (NHE)) to create electrons which were reductive enough to react with protons to hydrogen
Summary
Semiconductor-based catalysis is a green technology, which gained considerable attention owing to its potential environmental applications, such as wastewater treatment, air purification and degradation of different organic contaminants [1,2,3]. The large band gap energy for TiO2 (3.0–3.2 eV), requiring UV light that occupies around 5% of solar energy for excitation, limits its applications to a great extent [5] Another difficulty is the high recombination rate of the photoexcited electron-hole pairs in TiO2 [6]. Su et al prepared large surface area nanosized LaFeO3 particles by employing SBA-16 as a hard template and compared its visible light activity for RhB degradation with that of LaFeO3 prepared by the citric acid assisted sol-gel route [21]. LaFeO3 perovskite by the sol-gel route and claimed activity for photocatalytic hydrogen generation under visible light irradiation. Citric acid assisted sol-gel was chosen as a synthesis route because, in general, it is a suitable method for the synthesis of nanopowders with a well-developed high specific surface area obtained at low calcination temperature and short times without employing expensive sacrificial structure-directing agents or template structures. As for Tijare et al, we attempted hydrogen generation, failed with that and suspected it was based on the Mott-Schottky plots calculating band positions that the conduction band edge of LaFeO3 was too positive than the reduction potential of H2 /H2 O (0 V vs. NHE) to create electrons which were reductive enough to react with protons to hydrogen
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
