“…3b, the spectra of all three samples show a peak at 667 cm −1 corresponding to the vibrational peak of Fe-O, indicating the existence of magnetic Fe 3 O 4 nanoparticles. 37 The three samples have multiple peaks at 1113 cm −1 , 1627 cm −1 and 3405 cm −1 which correspond to the C-O stretching vibration, aromatic ring stretching vibration, and O-H stretching vibration of PDA, respectively, indicating the presence of PDA. 38,39 In addition, a characteristic peak belonging to C^N appears at 2213 cm −1 in the spectra of m-CNTs@H-PDA-CN, indicating the successful modication of the -CN group.…”