Minor Cu modification endows inactive industrial FeSiBNbCu metallic glass with robust azo dye degradation activity

Soft-magnetic metallic glasses have been widely used in transformers, and the waste metallic glasses from industrial production and processing can be used in wastewater treatment as an environmentally friendly method. However, the chemical reactivity of the well-known industrial Fe_73.5Si₉B_13.5Nb₃Cu₁ metallic glass is suboptimal. To enhance its reactivity, Fe_73.5Si₉B_13.5Nb₃Cu₁ amorphous powders are pretreated using dilute CuSO₄ solutions, leading to the effective production of composite powders with Cu dispersed on their surfaces. High-density micro-Cu/Fe electrochemical couples effectively activate the amorphous matrix through distributed galvanic cells, significantly enhancing the material's ability to degrade azo dyes. It is shown that depositing only 2.56 mg of Cu per gram of FeSiBNbCu powder largely increases the apparent rate constant for the degradation of Orange II from 0.0110 to 0.0412 min⁻¹, up by 275 %. When 25.6 mg of Cu is deposited, the synergy between the galvanic cell effect and the amorphous region reaches its optimum, achieving a maximum apparent rate constant of 0.0698 min⁻¹, a remarkable 535 % improvement. This method is currently the most economical and efficient way to activate the alloy, providing a new avenue for applying inactive waste Fe-based metallic glasses in wastewater treatment and other chemical applications. © 2025 Elsevier B.V.