Synergistic strategy of solute environment and phase control of Pb-based anodes to solve the activity-stability...

The contradiction between the activity and stability of metal anodes exists extensively, especially in acid electrooxidation under industrial-level current density. Although the anode modification enhanced the initial activity of anodes, its long-term activity is limited by anode slime accumulation. Herein, a synergistic strategy, coupling the solute environment with the phase control of anodes, is proposed to achieve the trade-off between activity and stability of Pb-based anodes in concentrated sulfuric acid electrolysis. Non-exogenous Mn²⁺ motivated a series of positive behaviours of reactive-oxygen-species capture, anode reconstruction and corrosion-dependent activity alleviation. The synergistic effects, which are crystal phase-dependent, mainly benefit from the continuous self-healing ability of the specific crystal phase of MnO₂ on the anodes by the coexisted Mn²⁺. Compared with Mn²⁺/α-MnO₂, Mn²⁺/γ-MnO₂ exhibited outperformed activity and stability in boosting oxygen evolution reaction (OER) and reducing hazardous pollutants, which resulted from the energy difference in the rate-determining step of OER and in the selectivity priority of Mn²⁺/MnO₂ oxidation pathway. Interestingly, the pre-coated γ-MnO₂ on the anode also presents excellent inheritance, guaranteeing the unchanged crystal phase of MnO₂ and the high performance in ultra-low hazardous slime generation in subsequent Mn²⁺ oxidation. The sustainability of Mn²⁺/γ-MnO₂ was proved in the operating hydrometallurgy conditions on Pb-based anodes. This strategy offers a promising approach for this common issue in electrooxidation-related areas.