The magnetic nanoparticles that are easy to recycle have tremendous potential as a suitable catalyst for environmental toxic dye pollutant degradation. Rationally engineering shapes and tailoring the size of nanocatalysts are regarded as an effective manner for enhancing performances. Herein, we successfully synthesized three kinds of MnFe₂O₄ NPs with distinctive sizes and shapes as catalysts for reductive degradation of methylene blue, rhodamine 6G, rhodamine B, and methylene orange. It was found that the catalytic activities were dependent on the size and shape of the MnFe₂O₄ NPs and highly related to the surface-to-volume ratio and atom arrangements. Besides, all these nanocatalysts exhibit selectivity to different organic dyes, which is beneficial for their practical application in dye pollutant treatment. Furthermore, the MnFe₂O₄ NPs could be readily recovered by a magnet and reused more than ten times without appreciable loss of activity. The size and shape effects of MnFe₂O₄ nanoparticles demonstrated in this work not only accelerate further understanding the nature of nanocatalysts but also contribute to the precise design of nanoparticles catalyst for pollutant degradation.

易于回收的磁性纳米粒子具有巨大的潜力，可以用作降解环境有毒染料污染物的合适催化剂。合理地设计形状和调整纳米催化剂的尺寸被认为是提高性能的有效方法。在这里，我们成功地合成了三种具有独特尺寸和形状的MnFe ₂ O ₄ NPs作为催化剂，用于亚甲基蓝，若丹明6G，若丹明B和亚甲基橙的还原降解。发现催化活性取决于MnFe ₂ O ₄的大小和形状。NPs与表面体积比和原子排列高度相关。此外，所有这些纳米催化剂对不同的有机染料都具有选择性，这有利于它们在染料污染物处理中的实际应用。此外，MnFe ₂ O ₄ NPs可以很容易地被磁铁回收并重复使用十次以上，而不会造成明显的活性损失。这项工作证明了MnFe ₂ O ₄纳米颗粒的尺寸和形状效应，不仅加速了对纳米催化剂性质的进一步了解，而且还为用于污染物降解的纳米颗粒催化剂的精确设计做出了贡献。