Solution combustion synthesis of novel PrFeO3/CeO2 nanocomposite with enhanced photo-Fenton activity under visible light

Abstract

In this study, we successfully synthesized PrFeO3/CeO2-based nanocomposites with different mass contents of СeO2 (0–18 wt%) via solution combustion with subsequent heat treatment in air. The results of EDXS and PXRD confirmed the presence of two phases in nanocomposites: a PrFeO3 orthorhombic phase with an average crystallite size of 13.6–36.6 nm and a СeO2 cubic phase in the form of an ultradisperse phase with an average particle size of 7.4–11.5 nm depending on the mass content of СeO2. We characterized the morphology, porosity, and specific surface structure of the powders by scanning electron microscopy, transmission electron microscopy, and adsorption–structural analysis, which established the foam-like morphology of nanopowders with a predominantly mesoporous structure. The specific surface area varied in the range of 8.8–19.4 m2/g for different СeO2 contents. We studied the optoelectronic properties of the nanocomposites with UV–visible diffuse reflection spectroscopy, which determined the values of the band gap of the PrFeO3 phase actively absorbing radiation in the visible region (2.07–2.13 eV). Based on the adsorption–photocatalytic properties of the obtained nanocomposites, we established the presence of a synergistic effect from the addition of CeO2 to PrFeO3. We studied the adsorption capacity of the samples during the adsorption of methyl violet, and we analyzed the resulting adsorption isotherm in accordance with the Freundlich model. The obtained results indicated increased dye adsorption in the presence of CeO2, with the maximum value of Kf = 45.7 observed at 15 wt%. We studied the photocatalytic Fenton-like activity of nanopowders during the degradation of methyl violet under the influence of visible light. We established he presence of a positive effect of CeO2 additive. At 9 wt% content, the maximum photocatalytic reaction rate constant was reached at 0.056 min−1, which was previously unavailable for analogical Fenton-like photocatalysts based on REE orthoferrites. Based on the conducted studies, we propose a possible mechanism of the photo-Fenton-like decomposition of organic pollutants in the presence of PrFeO3/CeO2 under the influence of visible light. The obtained nanocomposite materials were also characterized by high cyclic stability and the potential for magnetically controlled separation from the reaction solution, showing their potential as a basis for photocatalysts in wastewater treatment from dyes and other organic pollutants.