Axial Sulfur Ligation Unlocks the Rigidity of p-Block Aluminum Single-Atoms for Accelerated Oxygen Reduction.

Main-group single-atom catalysts (SACs) offer improved Fenton resistance but suffer from catalytic inertness due to rigid, delocalized s/p-bands. Herein, we report a targeted "p-band engineering" strategy to unlock the oxygen reduction reaction (ORR) activity of aluminum via an axially sulfur-coordinated architecture (AlN4-S). Theoretical and spectroscopic analyses indicate that this asymmetric S-ligation drives vertical charge polarization and shifts the spin-summed occupied Al pz-state centroid. These coupled changes rebalance oxygenated-intermediate adsorption by mitigating the overly strong Al-*OH thermodynamic sink, shifting the potential-determining step to *OOH formation with a maximum uphill free-energy change of 0.61 eV at U = 1.23 V. In situ ATR-SEIRAS and in situ DRT impedance support more facile intermediate progression and reduced charge-transfer resistance. Consequently, the engineered AlSNC catalyst delivers an ORR half-wave potential of 0.920 V. In practical zinc-air batteries, it achieves a 185.6 mW cm-2 peak power density and operation for over 1500 h under the reported cycling protocol. This work provides a framework for ligand-induced p-band modulation that combines Fenton resistance with high electrocatalytic activity.