Efficient Modulation d/p‐Band Center Proximity in Birnessite‐Type MnO 2 by Cation/Anion Co‐Doping for Enhanced Dual‐Ion Storage

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Abstract The wide band gap of δ‐MnO 2 and the restricted regulation of the p‐band center ( p ) of active oxygen atoms hinder electron conduction and ion diffusion during zinc storage. Heteroatom doping has proven effective in improving zinc storage. However, the regulation of p solely through cation doping is comparatively constrained. Herein, a cation/anion co‐doping strategy is proposed to simultaneously adjust the p of oxygen and the d‐band center ( d ) of Mn by establishing Mn–O–Ca and Mn─N bonds in Ca/N co‐doped δ‐MnO 2 (Ca/N‐MnO 2 ). This co‐doping effect induces a shift in the predominant stretching vibration mode of Mn─O bonds in [MnO 6 ] octahedra, resulting in a decreased d/p‐band center proximity (Δ d‐p ) of 1.688 eV (1.750 eV for δ‐MnO 2 ). Consequently, both adsorption capacity and adsorption/desorption rates of Zn 2+ /H + ions are enhanced. Theoretical calculations further reveal that co‐doping significantly triggers the optimization of the band gap, migration energy barrier, and adsorption energy. As a result, Ca/N‐MnO 2 achieves a remarkable reversible capacity of 192.7 mAh g −1 at 1.0 A g −1 after 200 cycles and exceptional rate performance. Furthermore, the energy enhancement mechanisms are thoroughly elucidated. This synergistic d/p‐band center regulation strategy offers significant potential for efficient energy storage applications.

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