Synergistic function of iron and cobalt in metallic glasses for highly improving persulfate activation in water treatment

Although metallic glasses (MGs) with unique disordered atomic structure have increasingly attracted great research interest as one of the most innovative heterogeneous catalysts in water remediation, few works focused on the synergistic role of different elemental constituents to well understand their superb catalytic performance. Herein, Co atoms were selected to partially substitute for the Fe elements in Fe-based MGs to study the corresponding synergistic catalytic function in dye degradation. Experimental results demonstrated that the Fe₃₆Co₃₆Si_4.8B_19.2Nb₄ MG with a kinetic rate constant of k = 0.06 min⁻¹ degrades rhodamine B (RhB) dye 20 times faster than the Fe_73.5Si_13.5B₉Cu₁Nb₃ MGs with k = 0.003 min⁻¹. Three types of dye including RhB, methylene blue (MB) and malachite green were investigated to draw attention to the broad, practical applications. Various chemical parameters, such as catalyst dosage, persulfate concentration, and dye concentration, were also studied. Quenching experiments indicated that the highly active hydroxyl (⋅OH) and sulfate (SO₄⋅⁻) radicals are largely produced from persulfate by the activation of the Fe₃₆Co₃₆Si_4.8B_19.2Nb₄ MG catalyst. This critical work uncovers a new paradigm to establish an effective approach for alloy design in widespread catalytic applications.