Non-noble metal nickel-based catalysts drive atomic H*-mediated electro-Fenton process for highly efficient tetracycline removal: A breakthrough in economy of H*

The H*-mediated electro-Fenton system, a novel byproduct-free H 2 O 2 activation technology, faces economic and universality challenges. This study fabricated a non-noble nickel-based catalyst to replace palladium (Pd), constructing a sandwich-structured NiO/oxidized carbon black electrode (SE-NiO/OCB) enriched with three-phase interfaces (TPI) for tetracycline (TC) removal. SE-NiO/OCB demonstrated efficient catalysis of atomic H* generation, achieving a significantly higher ·OH exposure of 19.18 × 10 −12 M·s compared to SE-OCB (5.37 × 10 −12 M·s). Additionally, the SE-NiO/OCB exhibited a remarkable TC removal efficiency of 96.7 % within 90 min, far exceeding SE-OCB (55.9 %). By leveraging H + /H 2 O as H* sources, the SE-NiO/OCB maintained ≥ 83.4 % TC removal across a broad pH range of 3–11, validating exceptional pH adaptability. Additionally, SE-NiO/OCB achieved a removal rate of ≥ 86.7 % for multiple tetracycline antibiotics at neutral pH, underscoring its broad applicability. The cost of utilizing SE-NiO/OCB to drive the H*-mediated E-Fenton reaction for TC removal was merely 0.05 RMB/(mg TC), which was significantly lower than that of noble metal catalysts. Thus, this work resolved critical economic and universality limitations in H*-mediated electro-Fenton processes, advancing scalable antibiotic wastewater treatment strategies.