Facile one-step synthesis of Fe-doped Mo3(O,S)4−x/La4Mo2O11 nanocomposites for efficient photodegradation of dye pollutants†

Visible-light-driven photocatalysis is an efficient and environmentally benign approach to mitigate organic pollutants from waste effluents. A facile one-step precipitation method was used to synthesize Fe–Mo₃(O,S)_4−x/La₄Mo₂O₁₁ (FeLaMoOS) nanocomposites. The as-prepared materials were characterized by XRD, SEM, HR-TEM, XPS, PL, EIS, photocurrent, and UV-visible spectroscopy. The type I heterojunction formed between Fe–Mo₃(O,S)_4−x and La₄Mo₂O₁₁ exhibited a maximum light absorption response in the visible spectrum. The FeLaMoOS composite (13% Fe and 20% La) demonstrated the highest degradation efficiency, degrading 97.5% MO and 99.2% RhB in 90 min. The removal efficiency of MB was 99.6% after 45 min of magnetic stirring in the dark. The enhanced catalytic efficiency can be attributed to the effective charge separation of photoinduced e⁻–h⁺ pairs due to doping and heterojunction formation. Superoxide radicals (O₂˙⁻) played a dominant role, while hydroxyl radicals (˙OH) played only a minor role, in the photocatalytic degradation process. Possible photocatalytic degradation mechanisms of organic dye molecules were proposed, based on the active radical species involved and the band potentials of the photocatalysts. This study can be used to establish a simple and efficient strategy for designing reusable composite photocatalysts for the degradation of organic dyes.