A facile one-step method for synthesis of magnetic core–shell nanocomposite composed of h-Fe₃O₄ (hollow Fe₃O₄) core and stable PDA (polydopamine) shell with functional Ag NPs (silver nanoparticles) evenly distributed between them is developed. The h-Fe₃O₄@Ag/PDA nanocomposite showed excellent catalytic activity in the reaction for reducing azo dyes (methyl orange, methylene blue, and congo red), and the ratios of k values to the weight of h-Fe₃O₄@Ag/PDA were calculated to be 0.302, 0.0545, and 0.895 min⁻¹ mg⁻¹, respectively. Besides, the h-Fe₃O₄@Ag/PDA nanocomposite also exhibited good antibacterial activity in the experiment of culturing Bacillus subtilis, and the MIC (minimum inhibitory concentration) was as low as 12.5 μg/mL. Because the Ag NPs will not be leached in the solution under the protection of the PDA shell, the catalytic and antibacterial activities of h-Fe₃O₄@Ag/PDA nanocomposite could maintain more than 90% after five cycles. Intriguingly, this simple synthetic method can be extended to fabricate different multifunctional nanocomposites such as the spherical SiO₂@Ag/PDA and rod-like Fe₂O₃@Ag/PDA. Overall, the facile fabrication process, the superior catalytic and antibacterial activity, and the excellent stability, endow the h-Fe₃O₄@Ag/PDA to be a promising nanocomposite.

一种简便的一步法合成由 h-Fe ₃ O ₄（空心 Fe ₃ O ₄）核和稳定的 PDA（聚多巴胺）壳组成的磁性核壳纳米复合材料，功能性 Ag NP（银纳米粒子）均匀分布在它们之间发达。h-Fe ₃ O ₄ @Ag/PDA纳米复合材料在还原偶氮染料（甲基橙、亚甲蓝和刚果红）的反应中表现出优异的催化活性，k值与h-Fe ₃ O的重量比₄ @Ag/PDA 分别计算为 0.302、0.0545 和 0.895 min ^-1 mg ^-1。此外，h-Fe ₃ O₄ @Ag/PDA纳米复合材料在培养枯草芽孢杆菌的实验中也表现出良好的抗菌活性，MIC（最低抑菌浓度）低至12.5 μg/mL。由于在PDA壳的保护下Ag NPs不会在溶液中浸出，因此h-Fe ₃ O ₄ @Ag/PDA纳米复合材料的催化和抗菌活性在5个循环后仍能保持在90%以上。有趣的是，这种简单的合成方法可以扩展到制造不同的多功能纳米复合材料，如球形 SiO ₂ @Ag/PDA 和棒状 Fe ₂ O ₃@Ag/PDA。总体而言，简便的制造工艺、优异的催化和抗菌活性以及优异的稳定性使 h-Fe ₃ O ₄ @Ag/PDA 成为一种很有前途的纳米复合材料。