fig3

Figure 3. (A) Zn²⁺ intercalation and H⁺ conversion reaction mechanism in δ-MnO₂. Reprinted with permission^[89]. Copyright 2019, John Wiley and Sons; (B) The insertion energies of H⁺ or NH⁴⁺ ions in MnO₂. Reprinted with permission^[32]. Copyright 2021, John Wiley and Sons; (C) The discharge of tunnel-like ε-MnO₂ stockpiled H⁺ and Zn²⁺. Reprinted with permission^[90]. Copyright 2022, Elsevier; (D) The synthetic process of CuMO electrode. Reprinted with permission^[92]. Copyright 2022, Elsevier; (E) Schematic illustration of the preparation of TMA-MnO₂. Reprinted with permission^[1]. Copyright 2024, Elsevier.