Magnetically separable sulfur-doped SnFe₂O₄/graphene nanohybrids for effective photocatalytic purification of wastewater under visible light

In this report, magnetically recoverable sulfur-doped SnFe₂O₄/graphene (S-SFO/GR) nanohybrids have been successfully developed via a facile solvothermal method. The characterizations on the structural, morphology, and optical properties of the nanohybrids indicate that S-SFO particles are successfully embedded on the GR nanosheets. The photocatalytic activity has been evaluated by photocatalytic degradation of chlorotetracycline under visible light irradiation. Among the composites with various mass ratios, the quasi-first-order rate constant of the nanohybrids formed with 9 wt% S in SFO and 15 wt% GR (9S-SFO/GR-15) can reach as high as 1.83 min⁻¹, which is much higher than that of SFO (0.68 min⁻¹) and SFO/GR (0.91 min⁻¹), confirming the important role of S and GR for the photocatalytic process. The combination of the three components of S, SFO, and GR has enhanced the visible light absorption capability and inhibited the recombination of photogenerated electron-hole. The 9S-SFO/GR-15 nanohybrids can be recovered easily by a magnet and reused for five times with remained photocatalytic efficiency about 70%. A possible catalytic mechanism explaining the efficient photocatalytic performances of the prepared nanohybrids has been proposed.