Electrosynthesis of High-Valent Iridium-Oxo Species for Efficient Oxygen Transfer Defluorination

Efficient defluorination of persistent fluorinated pollutants remains a critical challenge, as conventional oxidant-dependent methods suffer from limited efficacy and poor interference resistance. While enzymatic oxygen transfer defluorination employs high-valent metal-oxo (HVMO) species for selective C-F bond cleavage, replicating this process via an oxidant-free electrochemical synthesis has been elusive. Here, we report an oxidant-free electrochemical platform using low-valent Ir single atoms (+2.0) on titanium foam (L-Ir₁/TF) to generate high-valent Ir-oxo (HVIO) species directly from H₂O. The higher d-electron count of low-valent Ir enhanced π-backdonation from Ir 5d to O 2p orbitals, concentrating charge density on the axial oxygen. This elevated electrostatic repulsion suppresses competitive *OOH formation, achieving an exceptional HVIO production rate of 16,920 μmol h^-1 g_Ir^-1, 1.7 times higher than its high-valent Ir single atom (+4.3) counterpart (H-Ir₁/TF). The resultant HVIO species on L-Ir₁/TF selectively cleaved C-F bonds via electrophilic addition, achieving 99.4% fluconazole defluorination in 5 h (surpassing H-Ir₁/TF by 2.3 times and PbO₂ by 6.7 times). This work establishes single-atom oxidation-state engineering as a new paradigm for green HVMO synthesis, enabling the sustainable degradation of recalcitrant fluorinated contaminants.