Engineering Mn-confined Fe0-carbon with isolated oxygen-containing groups breaks the bottleneck for concurrent self-driven Fenton degradation of antibiotics and heavy metals immobilization.

Fe0-C presents a promising remediator for co-contamination of antibiotics and heavy metals (HMs) in redox-oscillating soil/water, but bottlenecks of reactive oxygen species (ROS) scavenging and Fe deactivation remain unresolved. This study innovatively engineered a multi-site Mn-zerovalent iron biochar (Mn-Fe0-BC) via stepwise carbon electron donation, integrating a Mn-O-confined Fe0 structure, abundant persistent free radicals (PFRs), and surface carboxyl groups to simultaneously establish a novel rate-limiting O2 reduction (ORR)-Fenton cascade and facilitate HMs fixation. Under dark air conditions, Mn-Fe0-BC prominently co-removed tetracycline (TC) and cadmium (Cd2+) (>91%), reaching 58.2% TC mineralization within 5 h, improving ⋅OH yields by 4.8-6.9 times of Fe0-BC and Fe0. Enhanced ⋅OH yield resulted from a consecutive 1e- ORR process, synergistically driven by Mn-O-confined Fe0 and PFRs, enabling controllable production and activation of H2O2 to curb ROS scavenging. Surface Mn prompted intermediate ⋅O2- formation by donating electrons to O2, enabling stepwise O2→⋅O2-→H2O2 conversions, thus regulating H2O2 supply to Fe0 core for rate-limiting Fenton. This synergy prevents detrimental H2O2 buildup and associated ROS scavenging-Fe0 passivation, resulting from Fe0-mediated violent 2e- ORR (bypassing ⋅O2-). Interestingly, ·O2- disproportionation was suppressed by ⋅O2--PFRs bonding, synergistically enhancing FeII regeneration and ⋅OH generation. Simultaneously, with Fe0 isolated by Mn-O "barrier", -COOH complexation (dominant) and Mn-ion exchange enhanced Cd2+ fixation, while preserving Fe0 redox-activity from HMs passivated interference. This work provided a novel paradigm for engineering Fe0-C materials with separated redox-adsorption sites towards self-driven concurrent antibiotics degradation and HMs immobilization, opening new avenues for sustainable remediation of co-contaminated environments.