Reconstruction of Ultrafine MnS-Induced Vacancy-Rich Co₉S_6.29 Precatalysts in Mesoporous S-Doped N-Rich Hollow Carbon Nanotubes Enables Dynamic O-Vacancy Cycling for High-Performance Zn-Air Batteries

Zn-air batteries (ZABs) hold great promise when the air cathode offers abundant active sites, fast kinetics, and high reversibility for oxygen reduction/evolution reactions (ORR/OER). Here, we report vacancy-rich Co₉S₆.₂₉ precatalysts formed via ultrafine MnS-induced lattice distortion in mesoporous S-doped pyridinic/graphitic N-rich hollow carbon nanotubes (CM@SNHCTs), synthesized through in situ sulfidation and Zn/melamine evaporation from polydopamine-coated Mn–Co/Zn metal–organic frameworks. MnS-induced Co₉S₆.₂₉ formation enables ∼fourfold higher capacitance than IrO₂, while the SNHCT generates Zn/melamine-evaporated mesoporous S-doped pyridinic N-rich channels for rapid ion transport and graphitic N-rich networks for facile electron conduction. CM@SNHCT precatalysts reconstruct into CoOOH/CoO active phases, enabling O-vacancy formation via OH⁻ desorption during ORR and bidentate O₂ adsorption during OER, as well as O-vacancy healing governed by OH⁻ adsorption and deprotonation, as confirmed by operando Raman spectroscopy and ¹⁸O-labeled differential electrochemical mass spectrometry. Density functional theory calculations reveal low Gibbs free-energy barriers for oxygen intermediates after reconstruction, while strong CM-SNHCT binding ensure structural stability. Consequently, CM@SNHCT outperforms Pt/C for ORR and IrO₂ for OER with electrochemical stability over 5000 cycles. Moreover, the ZAB assembled with CM@SNHCT cathode and high-capacity Zn anode achieves near-theoretical energy density (993.8 Wh·kg⁻¹) and stable voltages after 250 charge–discharge cycles, establishing a state-of-the-art ZAB platform.