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

•1D Fe3O4/C composite microrods were synthesized by one-pot magnetic field-induced solvothermal reaction.•A uniform ZnO nanocrystal layer was facilely coated onto the 1D Fe3O4/C composite microrods.•The size of ZnO nanocrystals and the thickness of coating layer can be easily tuned.•The as-prepared products exhibited enhanced photocatalytic activity for the decolorization of Congo red.•The photocatalysts can be readily recycled by a magnet with virtually no loss in catalytic efficiency.

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.

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