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.

Hydrothermal microwave‐assisted synthesis of LaFeO3 catalyst for N2O decomposition

“…One can see that both samples have almost the same spectra; a wide band with a maximum at 3400 cm −1 can be attributed to stretching vibrations of O-H groups of adsorbed water on the perovskite surface; in the range of 800-1700 cm −1 there are no noticeable absorbance bands, so one can say that both samples do not contain organic and nitrogen-containing compounds formed as products of urea decomposition adsorbed on the particle surface; a peak at 560 cm −1 is attributed to stretching vibrations of Fe-O bonds, 81,82 and a slightly visible shoulder at 510 cm −1 can be assigned to stretching vibrations of La-O bonds. 83 During a detailed examination at the range of 400-700 cm −1 , there are no bands corresponding to hematite (540 and 470 cm −1 ) 84 and lanthanum hydroxide (660 and 645 cm −1 ) phases.…”

Examination of Photocatalyzed Chlorophenols for Sequential Photocatalytic-Biological Treatment Optimization

“…AVSS (active volatile suspended solids), VSS (volatile suspended solids). (11) where f cv is the COD/VSS ratio of the sludge (mg COD/mg VSS), OUR i is the initial oxygen uptake rate (mg/L/h), V mL is the total volume of the mixture consisting of active sludge and working solution containing chlorophenols (L), V ww is the volume of the working solution containing chlorophenols (L), X V is the volatile suspended solids (VSS) concentration of the mixture added to the batch experiment (mg VSS/L), f av is the active fraction of the VSS, and 24 is the number of hours per day. The active fraction of the VSS (f av ) was calculated by using the equation proposed by Ekama et al [36].…”

“…Due to their specific characteristics, which place them in the category of toxic organic compounds, they have a negative effect on the aquatic ecosystem, and also on human health [3]. For this reason, a wide range of methods for removing them from aqueous solutions have been developed over time, the most known being adsorption on various adsorbents [4], and advanced oxidation processes [5,6] of which photocatalytic oxidation has received special attention lately [7][8][9][10][11]. Although many of these methods have been shown to be effective in removing chlorophenols from many aqueous systems, their large-scale application is often difficult both technically and economically.…”

Micro-emulsion synthesis of La1 − xCrxFeO3 nanoparticles: effect of Cr doping on ferroelectric, dielectric and photocatalytic properties

“…The LaFeO 3 perovskite with La as rare earth metal and Fe as transition metal is an important material due to their excellent physic-chemical properties (Peng et al 2016). For instance, it is employed in solid oxide fuel cells as a catalyst and also in various devices owing to its high piezoelectricity and promising dielectric properties (Ismael and Wark 2019). Doped LaFeO 3 perovskites have gained much attention due to enhanced properties and doping of LaFeO 3 have been reported by many researchers and there is lack of studies reporting chromium as dopant in order to enhance the physico-chemical characteristics of LaFeO 3 perovskites using different techniques, i.e., hydrothermal, microwave combustion, sol-gel, thermal combustion, coprecipitation and electrospinning (Cheng et al 2020;Choudhary, Uphade, and Pataskar 1999;Dhiman and Singhal 2019;Hu et al 2019;Huang et al 2020;Li et al 2018;Lin et al 2018;Lin et al 2019;Omari, Omari, and Barkat 2018;Rezanezhad et al 2020;Sukumar et al 2019).…”