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Figure 2.
(A) XRD of Fe3O4@SiO2 (a) and Fe3O4@SiO2@[Hpy]NTf2 (b); (B) SEM of Fe3O4 (a), Fe3O4@SiO2 (b), Fe3O4@SiO2@[Hpy]NTf2 (c).