Adjusting the 3d Orbital Occupation of Ti in Ti3C2 MXene via Nitrogen Doping to Boost Oxygen Electrode Reactions in Li–O2 Battery

Rationally designing efficient catalysts is the key to promote the kinetics of oxygen electrode reactions in lithium‐oxygen (Li‐O2) battery. Herein, nitrogen‐doped Ti3C2 MXene prepared via hydrothermal method (N‐Ti3C2(H)) is studied as the efficient Li‐O2 battery catalyst. The nitrogen doping increases the disorder degree of N‐Ti3C2(H) and provides abundant active sites, which is conducive to the uniform formation and decomposition of discharge product Li2O2. Besides, density functional theory calculations confirm that the introduction of nitrogen can effectively modulate the 3d orbital occupation of Ti in N‐Ti3C2(H), promote the electron exchange between Ti 3d orbital and O 2p orbital, and accelerate oxygen electrode reactions. Specifically, the N‐Ti3C2(H) based Li‐O2 battery delivers large discharge capacity (11 679.8 mAh g−1) and extended stability (372 cycles). This work provides a valuable strategy for regulating 3d orbital occupancy of transition metal in MXene to improve the catalytic activity of oxygen electrode reactions in Li‐O2 battery. The incorporation of nitrogen into Ti3C2 MXene can effectively regulate the 3d orbital occupation of Ti and thus increase the relative content of Ti3+ species, which is beneficial for the catalytic activity of nitrogen doped Ti3C2 MXene toward oxygen redox reactions. Thus, the electrochemical performance of Li–O2 battery based on nitrogen doped Ti3C2 MXene is significantly improved.