Photocatalytic degradation of methyl orange under visible light by a novel magnetic recyclable Sb2S3@Fe3O4 composite photocatalyst

In this study, a novel Fe 3 O 4 @Sb 2 S 3 magnetic composite photocatalyst was synthesized via a facile ultrasonic-assisted route to produce magnetically separable Sb 2 S 3 -coated Fe 3 O 4 nanoparticles (F@S-x, x denotes CS 2 volume). The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS) and vibrating sample magnetometer (VSM) analysis. Morphological studies showed the formation of composite wherein Sb 2 S 3 nanoparticles are located on the surface of Fe 3 O 4 particles. Photocatalytic activity was evaluated by degradation of methyl orange (MO, 10 ppm) under LED as visible irradiation. While pure Fe 3 O 4 showed negligible photocatalytic activity and pure Sb 2 S 3 achieved ~26% MO degradation in 20 min, Fe 3 O 4 @Sb 2 S 3 composites (F@S-0.1, F@S-0.3, F@S-0.6) exhibited markedly enhanced performance, achieving near-complete degradation within 20 min. The results indicated that the corresponding reaction rate constants (k) increased from 0.002 min −1 for Fe 3 O 4 and 0.015 min −1 for Sb 2 S 3 to 0.150–0.189 min −1 for F@S composites. Radical trapping experiments identified superoxide radicals ( • O 2 − ) and photogenerated holes as the primary active species, with • O 2 − playing the dominant role. Furthermore, the magnetic F@S-0.3 photocatalyst displayed excellent recyclability, maintaining high activity (~100%) over five consecutive cycles with facile magnetic recovery. These results demonstrate that Fe 3 O 4 @Sb 2 S 3 composite photocatalyst are promising, stable, and easily recoverable visible-light photocatalysts for rapid degradation of organic dyes in water.