Photocatalytic Activity Enhancement in Methylene Blue Degradation by Loading Ag Nanoparticles onto α-Fe2O3

Abstract

Modified alpha iron(III) oxide (α-Fe2O3) used as visible light-driven photocatalysts were successfully synthesized with different ratios of silver nanoparticles (AgNPs) by coupling a hydrothermal method with an impregnation method. The samples were characterized by their physicochemical properties using X-ray powder diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, UV-visible diffuse reflectance spectroscopy, Brunauer–Emmett–Teller (BET) specific surface area and photoluminescence spectroscopy (PL). The X-ray powder diffraction results indicated that all the samples were in the rhombohedral (hexagonal) phase of α-Fe2O3. The photocatalytic activities of Ag-loaded α-Fe2O3 were evaluated through the mineralization of methylene blue (MB) under visible light illumination. The α-Fe2O3 photocatalytic results showed that loading with Ag nanoparticles could improve the photocatalytic activities effectively. It was found that 5.0 wt % Ag-loaded α-Fe2O3 was a better photocatalyst than others under the same reaction conditions. Its efficiency was 68.6% at 150 min at a kinetic rate constant (k) of 7.9 × 10−3 min−1.