Cadmium-Sacrifice Mediated Vacancy Engineering on Manganese Phosphide for Enhancing Oxygen Reduction and Zn-Air Batteries

Exploiting the efficiency and durability of oxygen reduction reaction (ORR) electrocatalysts for Zn-air batteries (ZABs) remains a tremendous challenge. In this work, a novel sacrificial agent strategy was employed to construct vacancy-rich MnP/Mn5.64P3 heterostructure nanobicrystals on nitrogen-doped carbon (MnxPy/NC). Multiple ex/in situ characterizations reveal that the Cd sacrificial agent induces structural reconstruction and vacancy generation, which accelerates electron transfer, optimizes the transformation of intermediates, and suppresses the production of byproducts. As a result, the optimized MnxPy/NC catalyst shows remarkable ORR activity, with an onset potential of 0.93 V and a limited current density of 5.6 mA cm–2. Notably, MnxPy/NC-based aqueous ZABs exhibit an impressive power density (135.9 mW cm–2) and an ultralong cycle life (600 h), and the corresponding flexible device demonstrates excellent mechanical stability. This work presents a strategy for designing highly active transition metal phosphide-based catalysts using the sacrificial agent toward the ORR.