Visible-light-driven magnetic heterojunction as a promising photocatalysts has received much attention in environmental remediation. In this work, novel Z-scheme heterojunction MnZnFe 2 O 4 @Ag 3 PO 4 (MZFO@APO) magnetic photocatalysts with excellent visible-light-driven photocatalytic activity are successfully constructed and characterized. The photocatalytic activity for phenol degradation is measured, and photodegradation mechanism is investigated with EPR, radical trapping experiments, and LC–MS. It turns out that the heterojunction introduced MZFO exhibits good adsorption effect on visible light and the direct Z-scheme bandgap alignment of MZFO and APO significantly improves charge separation and electron transfer, outperforming that of pure APO. MZFO@APO-40% with 40% APO content shows the rapid photodegradation performance, obtaining a 100% removal efficiency of phenol (25 mg L −1 ) after 12-min visible light irradiation, and its kinetic constants are approximately 25.3 and 4.9 times higher than that of P25 TiO 2 and pure APO, respectively. Especially, MZFO@APO-40% also possesses a high magnetic separation property and can be efficiently reused for 5 cycles. Additionally, EPR and radical trapping experiments confirm that h + , O 2 − , and 1 O 2 are the main active species in the photocatalytic process. Hydroquinone and small molecular organic acids such as maleic acid and oxalic acid are detected by LC–MS, which further indicates that the pathway of phenol degradation involves hydroxylation, open-ring reactions, and mineralization reactions. The novel addition of MZFO in photocatalyst construction has the potential to promote its application in environmental remediation.
The low activity of photocatalysts is mainly due to inefficient charge separation and low production of the active species. To overcome this challenge, we constructed an S-scheme CdIn 2 S 4 /MnZnFe 2 O 4 (CIS/MZFO) heterostructure, where the strong interface of the heterostructure leads to an upshift of the d-band center. CIS/MZFO shows higher charge transfer efficiency and oxygen adsorption/activation performance compared to CIS and MZFO separately, thereby increasing the production of ·O 2 − and h + active species. As a result, it demonstrats efficient photocatalytic degradation of tetracycline hydrochloride. The optimized CIS/MZFO heterostructure also shows good tolerance to various factors, such as inorganic ions, organic acids, pH and real water environments. The heterostructure also exhibits excellent magnetic recyclability and stability. Additionally, we propose a photocatalytic degradation pathway for tetracycline hydrochloride and evaluate the ecological toxicity that may arise from intermediates. This study provides an effective approach for the design of advanced photocatalysts.
An iron-based soft magnetic composite with Fe3O4-MnZnFe2O4insulation coating has been prepared by powder metallurgy method. This work investigated the microstructure and magnetic properties of Fe/Fe3O4-MnZnFe2O4powder cores. Scanning electron microscopy (SEM) coupled with an energy dispersive spectrometry (EDS) analysis indicated that the Fe3O4and MnZnFe2O4nanoparticles were uniformly coated on the surface of Fe powders. The co-existence of Fe3O4and MnZnFe2O4contributes to the preferable distribution of nano-sized insulation powders and excellent soft magnetic properties of soft magnetic composite (SMC) with high saturation magnetization Ms(215 A·m2/kg), low core loss (178.7 W/kg measured at 100 kHz, 50 mT), and high effective amplitude permeability of 114 (measured at 100 kHz). Overall, this work has great potential for realizing low core loss and outstanding soft magnetic properties of Fe-based powder cores.
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