Synthesis, characterization and catalytic performance of magnetic La0.7Sr0.3MnO3/α-Fe2O3 with p–n heterojunction structure
In this study, a solar-driven photocatalyst La 0.7 Sr 0.3 MnO 3 /α-Fe 2 O 3 (20%) with p – n heterojunction structure was synthesized and characterized. The magnetic, photocatalytic properties, Fenton-like action and the synergistic effect of the photocatalysis and Fenton-like on methyl orange (MO) degradation of La 0.7 Sr 0.3 MnO 3 /α-Fe 2 O 3 (20%) were also investigated. Results show that p – n heterojunction was formed, and it has considerable photocatalytic properties under ultraviolet light and solar irradiation. More importantly, La 0.7 Sr 0.3 MnO 3 /α-Fe 2 O 3 (20%) also exhibits Fenton-like catalytic performance in the presence of H 2 O 2 and oxalic acid (OA). The main reactive radicals of the La 0.7 Sr 0.3 MnO 3 /α-Fe 2 O 3 –H 2 O 2 –OA–sunlight system are h + , · OH and · O 2 − . The chemical oxygen demand removal rate of MO wastewater in La 0.7 Sr 0.3 MnO 3 /α-Fe 2 O 3 (20%)–H 2 O 2 –oxalic acid–sunlight system reached 72.4%; the value was higher than that of the sum of single photocatalysis (34.5%) and Fenton-like-dark system (27.6%), indicating that there is a synergistic effect between the photocatalysis and Fenton-like on MO degradation. In addition, La 0.7 Sr 0.3 MnO 3 /α-Fe 2 O 3 (20%) displays approximately superparamagnetism and has higher saturated magnetization ( M s ), low coercive force and residual magnetism. So it can be easily recovered by an external magnetic field and can be reused 6 times. It was anticipated that La 0.7 Sr 0.3 MnO 3 /α-Fe 2 O 3 (20%) with p – n heterojunction structure is a stable and reusable solar-light-driven magnetic photocatalyst and has great potential applications for wastewater treatment. Graphical abstract The magnetic La 0.7 Sr 0.3 MnO 3 /α-Fe 2 O 3 (20%) with p – n heterojunction structure was synthesized and characterized by different methods. The magnetic, photocatalytic properties, Fenton-like action and the synergistic effect of the photocatalysis and Fenton-like on methyl orange (MO) degradation of La 0.7 Sr 0.3 MnO 3 /α-Fe 2 O 3 (20%) were also investigated. It is not only a solar-driven photocatalyst with high efficiency, but also shows excellent Fenton-like catalytic effect. And the photocatalysis and Fenton-like system exhibited synergetic catalytic effect on MO degradation by La 0.7 Sr 0.3 MnO 3 /α-Fe 2 O 3 (20%). Furthermore, near superparamagnetic characteristics of the catalyst make it easy to recycle by the external magnetic field and can be reused for 6 times, suggesting that it is a stable multifunctional catalyst.
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