Magnetization of amorphous FeOOH chrysanthemum-like nanosheets under ambient conditions

The conversion of paramagnetic solid iron oxides to magnetic iron oxides has drawn considerable interest, but it's still challenging to carry out without heat treatment or irradiation. In this work, solid amorphous iron oxide chrysanthemum-like nanosheets synthesized by a smart redox strategy at the interface of a soap-free emulsion are magnetized at room temperature and under ambient pressure. An amorphous FeOOH hollow shell with needles towards water is produced by the reaction of cumyl hydroperoxide (CHPO) and iron(II) sulfate (FeSO₄) at the interface of the emulsion generated by ultrasound and torn up into chrysanthemum-like nanosheets simultaneously. With the presence of noble metal ions, such as Au³⁺, the magnetization of the nanosheets was carried out as soon as sodium borohydride (NaBH₄) was introduced into the dispersion. The magnetic chrysanthemum-like nanosheets present saturation magnetization (Ms) of 32 emu g^-1 and can be placed linearly in a magnetic field.