Enhancement of peroxymonosulfate activation with nickel foam-supported CuCo₂O₄ for tetracycline degradation: Performance and mechanism insights

The modulation of bimetallic oxide structures and development of efficient, easily recoverable catalysts are expected to effectively overcome the limitations associated with powdered catalysts in activating peroxymonosulfate (PMS). In this study, CuCo₂O₄ was successfully immobilized on the surface of nickel foam (NF) via an electrodeposition-calcination procedure, with highly efficient activation of PMS for tetracycline (TC) degradation (0.55 min⁻¹). Besides acting as a support carrier and providing ample active sites, NF mediated electron transport, prevented the leaching of metal ions and enhanced the efficiency of recycling. Density functional theory (DFT) calculations and experimental tests illustrated that Cu/Co dual-sites can efficiently adsorb PMS, enabling simultaneous reduction and oxidation reactions. The dual-site synergy substantially decreased the adsorption barrier and increased the electron transfer rate. Especially, the Cu⁺/Cu²⁺ redox couple acted as an electron donor and facilitated rapid charge transfer, leading to the conversion of Co³⁺ to Co²⁺. Moreover, the CuCo₂O₄@NF + PMS system effectively eliminated TC by employing radical pathways (SO₄^•−, ^•OH) and nonradical processes (¹O₂, e⁻). Therefore, this study introduces a new approach to overcome the limitations of powdered bimetallic oxides, providing a promising solution for practical applications.