Unraveling The Electrocatalytic Mechanism of Uranium Immobilization at MXene Edge Sites

Abstract The electrocatalytic role of Ti ₃ C ₂ T _x MXene in U(VI) immobilization has remained largely unexplored. Herein, a binder‐free electrode (TiMX/CNT‐COOH) is designed and its exceptional performance in electrochemically U(VI) extraction under square‐wave exchange (SWE) is demonstrated. The incorporation of carboxylated carbon nanotubes (CNT‐COOH) as a rigid spacer not only enhances structural disorder but also exposes abundant undercoordinated Ti edge sites and induces bond stretching (Ti─O and O─H), further boosting intrinsic catalytic activity. This synergistic effect interaction lowers the energy barrier of the rate‐determining step by 0.82 eV. Through integrated in situ Raman spectroscopy and density functional theory calculations, the dynamic U(VI)/U(V) transition is directly captured at Ti‐active edge sites, representing the first mechanistic elucidation of MXene‐based electrocatalysis for uranium. Consequently, the TiMX/CNT‐COOH cathode achieves an impressive uranium extraction capacity of 1,1719.96 mg g ⁻¹ with excellent cycling stability. This work offers fundamental insights into the electrocatalytic mechanism and provides a strategic framework for designing large‐scale electroactive materials for uranium recovery from wastewater.