Fig. 1. XRD patterns of AQ and BM ribbons. Insets are the photographs of AQ and BM ribbons.

Fig. 2. Visible colour change of AO7 solution during redox reaction using (a) AQ and (b) BM ribbons.

Fig. 3. UV-vis absorbance spectra of AO7 solutions during the redox reactions using (a) AQ and (b) BM ribbons; (c) normalized concentration change of AO7 solutions during the degradation process; (d) the ln (C0/Ct) vs. time curves for AQ and BM ribbons (T = 298 K, pH = 3, ribbon dosage = 10 g/L, CAO7 = 20 mg/L).

Fig. 4. Normalized concentration change of AO7 solutions at different degradation cycles during the redox reactions using (a) AQ ribbons and (c) BM ribbons; surface morphologies of (b) AQ ribbons after 2 degradation cycles and (d) BM ribbons after 12 degradation cycles.

Fig. 5. DSC curves recorded for AQ and BM ribbons. The inset is the magnified view of the rectangular region.

Fig. 6. MFM images of the magnetic structure on the (a) free and (b) wheel surfaces of AQ ribbons; MFM images of the magnetic structure on the (c) free and (d) wheel surfaces of BM ribbons. Height distributions on the (e) free surfaces of AQ and BM ribbons; height distributions on the (f) wheel surfaces of AQ and BM ribbons.

Fig. 7. SEM micrographs of AQ ribbons (a) before and (c) after reactions; SEM micrographs of BM ribbons (b) before and (d) after reactions. Insets show the compositions of corresponding samples obtained from EDS measurements.

Fig. 8. (a) Polarization curves and (b) Nyquist plots derived from EIS measurements for AQ and BM ribbons in AO7 solutions, and the insets correspond to the equivalent circuits.

Fig. 9. (a) Normalized concentration change of AO7 solutions using AQ, BM and AN ribbons during the degradation process, the inset shows the XRD curve of AN ribbons; SEM micrographs of AN ribbons (b) before and (c) after reactions.

Fig. 10. Possible degradation pathways of AO7 during the redox reactions using BM ribbons.

Fig. 11. Schematic diagram for the redox reaction process using BM ribbons.