Development of FeMnO3@Ag perovskite via sol-gel combustion for superior photocatalytic degradation of methyl orange under visible light irradiation

Abstract

Photocatalysis offers a promising and sustainable approach to dye degradation, delivering environmental advantages such as lower carbon emissions, heat energy savings, and the conservation of natural resources. In this study, FeMnO₃ (FMO) and Ag-doped FeMnO₃ (FMO-A) perovskites were successfully synthesized by sol-gel assisted combustion method and systematically examined for their structural, morphological, and optical characteristics in the context of methyl orange (MO) dye degradation. Structural analysis, utilizing XRD and Rietveld refinement confirmed FMO crystalline nature and the amorphous nature of Ag in FMO-A. Morphological assessment through FESEM and TEM disclosed distinctive microstructural features such as FMO displayed spherical-shaped particles, while FMO-A exhibited larger grains with mixed morphologies. UV–vis spectra determined optical band gaps (E_g) of 2.71 eV for FMO and 2.45 eV for FMO-A, suggesting enhanced potential for photocatalytic degradation, especially in the visible light range. Photocatalytic assessments revealed FMO-A superior decolorization efficiency at 84.2 % vs. 47.8 % for FMO after 120 min of visible light exposure, following first-order kinetics with a higher apparent rate constant than FMO. Dielectric analyses unveiled material electrical behavior, showcasing relaxation at lower frequencies and polarization resonance indicated by dielectric loss and tan δ. Complex modulus analysis disclosed diverse charge transport mechanisms. Nyquist plots highlighted decreased grain resistance in FMO-A, and conductivity variations with frequency demonstrated enhanced conductivity with Ag substitution. In summary, FMO-A exhibits promise as a visible light photocatalyst for efficient organic pollutant degradation, owing to its enhanced electrical conductivity and charge carrier transportation mechanisms.