Direct coating ZnO nanocrystals onto 1D Fe₃O₄/C composite microrods as highly efficient and reusable photocatalysts for water treatment

In this wok, we demonstrated a facile two-step method to directly coat a ZnO nanocrystal layer on the surface of one-dimensional (1D) Fe₃O₄/C composite microrods to form Fe₃O₄/C@ZnO core-shell microrods. Firstly, 1D Fe₃O₄/C composite microrods were successfully synthesized by one-pot magnetic field-induced solvothermal reaction according to our previous work. Sencondly, a uniform ZnO nanocrystal layer was facilely coated onto the 1D Fe₃O₄/C composite microrods via a modified hydrothermal process at a low temperature (60 °C). Importantly, the size of ZnO nanocrystals and the thickness of coating layer can be easily tuned by varying the concentration of Zn(Ac)₂·2H₂O in the solution. Further investigation has revealed that the as-prepared core-shell microrods exhibited enhanced photocatalytic activity for the decolorization of photosensitized dyes (Congo red) under visible-light illumination. Moreover, these magnetically separable photocatalysts can be readily recycled by a magnet with virtually no loss in catalytic efficiency. We believe this facile synthesis strategy provides a general and efficient way to synthesize other 1D magnetic nanocomposites for different functional applications.