Lattice Bromine‐Induced Pinning Effect Stabilizes Spinel Co ₃ O ₄ for Durable Bromine Radical‐Mediated Propylene Oxide Electrosynthesis

ABSTRACT

The electrochemical oxidation of propylene to propylene oxide (PO) using renewable electricity is a sustainable alternative to energy‐intensive industrial processes. However, this route is challenged by the high C═C activation barrier, competing oxygen evolution reaction (OER), and poor catalyst stability under high anodic potentials. Here, we report a bromine‐doped Co ₃ O ₄ nanosheet array supported on carbon paper (Br‐Co ₃ O ₄ /CP) that enables an efficient and stable bromine radical‐mediated propylene oxidation reaction (BrPOR). Lattice Br induces a pinning effect that enhances Co─O covalency, stabilizes the spinel Co ₃ O ₄ structure, and suppresses detrimental surface reconstruction to CoOOH. Consequently, Br‐Co ₃ O ₄ /CP delivers a PO Faradaic efficiency of 77.5% and a PO yield of 2.89 mmol h ⁻¹ at 200 mA cm ⁻² , while maintaining nearly 80% of its initial efficiency over 80 h. In situ spectroscopy and theoretical calculations reveal that Br doping lowers the water dissociation barrier, enhances propylene adsorption, and stabilizes Co─O bonds, thereby achieving efficient and durable BrPOR. This work demonstrates the effectiveness of lattice doping and pinning effects in stabilizing oxide catalysts for robust electrochemical oxidation reactions, offering a viable pathway toward industrial‐scale PO electrosynthesis.