S-scheme heterojunction FeS2/BaFe12O19 by in-situ sulfurization strategy for boosting photocatalytic degradation activity

Abstract

The development of S-scheme heterojunction photo-Fenton system with high catalytic activity is of great significance. Herein, FeS₂/BaFe₁₂O₁₉ (SBFO) S-scheme heterojunction composites were prepared by in-situ sulfurization of BaFe₁₂O₁₉, which were subsequently employed in the photo-Fenton technique (500 µL H₂O₂) for the effective degradation of 100 mL of imidacloprid (10 ppm). Utilizing the internal electric field (IEF) established between the in-situ grown FeS₂ and BaFe₁₂O₁₉, along with the synergistic effects arising from their suitable band structures, the optimized composite sample demonstrated a reaction rate of 0.1136 min⁻¹ (Kinetic model: R²＞0.98). In the presence of the internal electric field (IEF), electrons at the SBFO interface migrate from BaFe₁₂O₁₉ to FeS₂, thus establishing an S-scheme heterojunction that facilitates the efficient separation of charge carriers and the rapid generation of free radicals. Moreover, the sulfurized SBFO not only preserved its outstanding magnetic separation capability (21 emu/g) but also maintained over 90 % removal efficiency of imidacloprid after 4 cycles. Additionally, its morphology and structure remained comparable to those observed prior to the reaction. Furthermore, mung bean cultivation experiments were carried out to assess the toxicity of the intermediates. The rhizomes of mung beans grown with detoxified culture medium can grow to approximately 15 cm in length, which exhibit a considerable increase in length compared to the undetoxified rhizomes. The toxicity of intermediate products was further analyzed in detail using toxicity assessment software tools such as T.E.S.T and ECOSAR. Low-power LED lamps (30 W) demonstrate a degradation rate comparable to that of Xe lamp light sources (250 W) (LED: 0.1136 min⁻¹, Xe lamp: 0.0794 min⁻¹). This work offers an efficient approach for the degradation of organic pollutants by using magnetic material-based composites in combination with advanced oxidation technology.