Fig. 1. Schematic illustration of electrochemical degradation of azo dyes using Fe-based MG electrodes.

Fig. 2. (a) XRD and (b) DSC patterns of Fe-based MG ribbons before and after electrochemically degrading AO II aqueous solution with a voltage of 1?V.

Fig. 3. UV-vis absorption spectra of AO II aqueous solutions treated with Fe-based MG ribbons at a voltage of 1?V (a) and 0?V (c) for different reaction time, degradation efficiency and specific energy consumption of the electrochemical degradation processes (b) and degradation efficiencies for chemical process (d). The insets of (b) and (d) are the corresponding photographs of the AO II solution at different reaction time (C0?=?0.2?g?L-1; Edye: specific energy consumption).

Fig. 4. (a) Influence of cell voltage on degradation efficiency (C0?=?0.2?g?L-1; the inset of (a) is the degradation efficiency at a voltage of 0.5?V) and (b) influence of solution concentration on degradation efficiency and specific energy consumption (U?=?1?V, t?=?10?min).

Fig. 5. Comparison between Fe-based MG and Fe electrodes regarding degradation efficiencies (a), specific electrode mass consumption (b) and specific energy consumption (c) at different cell voltages (C0?=?0.2?g?L-1), specific energy consumption during the electrochemical experiments using Fe-based MG electrodes and some typical nonconsumable electrodes (d).

Fig. 6. (a) Influence of benzoic acid concentration on degradation efficiency and (b) a new degradation process initiated using initial dye concentration by adding AO II after 10?min of treatment (U?=?1?V,?C0?=?0.2?g?L-1).

Fig. 7. Degradation efficiencies of different cycles at 10?min (U?=?1?V,?C0?=?0.2?g?L-1).

Fig. 8. SEM micrographs of Fe-based MGs (a) and Fe (b) electrodes after electrocatalytic degradation reaction (U?=?1?V) and SEM micrograph of Fe-based MGs after degrading dye under open circuit conditions without a current (c).