Unveiling the Role of Ce 4f Orbitals in Modulating MnO₂ Oxygen Evolution Reaction Performance

Due to its strong acid and oxidation resistance, rutile β-MnO₂ is considered to be a highly promising acidic nonprecious metal OER catalyst. However, the direct electron supply located in the Mn-O energy band below the Fermi energy level (E_f) causes instability of the Mn-O bond, making the long-term activity and stability of β-MnO₂ poor. However, in this paper, introducing Ce 4f orbitals to construct a simultaneous Mn-O electronic configuration improved by the electronic buffer band through electronic coupling is proposed, thus enhancing the OER activity and stability. The combination of electronic structure characterization (XASF, XPS, in situ Raman, etc.) and theoretical calculation analysis reveals that the constructed Ce(f)-O(p)-Mn(d) orbital coupling electronic structure enhances the Mn-O covalent bonding and improves the adsorption capacity of O*, which enhances the OER activity of β-MnO₂. Moreover, Ce 4f acts as a buffer band to stabilize the Mn site and avoid the excessive oxidation of Mn, thus enhancing the stability of β-MnO₂.