Unraveling the Fluoride-Induced Interface Reconstruction Across Lead-Based Hierarchical MnO₂ Anode in Zinc...

Although the hierarchical manganese dioxide film electrode shows promise as a durable and catalytically active anode for zinc electrowinning, it often fails and deactivates when it is exposed to fluoride-rich environments. The lack of understanding regarding the mechanism behind fluoride-induced irreversible interface reconstruction hinders their practical application in large-scale energy-saving and pollution-reduction efforts. Here, we conducted multidimensional operando investigations to gain insights into the dynamic evolution across the film electrode interface with temporal and spatial resolution. Our findings reveal that electroosmosis of F^- initially triggers structural collapse and subsequent reconstruction of [MnO₆] units, followed by interaction with the spontaneous oxide film at the surface of lead substrate. Experimental studies and theoretical calculations indicate that F^- facilitates the irreversible transformation of γ-MnO₂ into more stable yet protective catalytic dual-defective α-MnO₂. Additionally, lower levels of F^- at the interface promote a change in microenvironmental pH within porous PbSO₄, triggering the development of microporous corrosion-resistant β-PbO₂ as the dominant phase. The combined effects of MnO₂ and interphase evolution effectively explain the abnormally elevated oxygen evolution overpotential. Then, the proposed appropriate application scenarios based on the corrosion behavior will serve as a practical guide for the implementation of the hierarchical manganese dioxide film electrode.