Enhancement of the synergy between high-spin sites for efficient oxygen electrocatalysis.

Abstract

To address the sluggish oxygen electrocatalytic kinetics and insufficient synergy between tetrahedral (Td) and octahedral (Oh) sites in spinel oxides, this work achieves targeted spin-state transition at Oh sites through a spin-control strategy. Material characterization and density functional theory (DFT) demonstrate that selective Mn occupation induces elevated Oh site spin states. The synergy between high-spin Td/Oh sites strengthens the quantum spin exchange interaction (QSEI) and promotes charge transfer efficiency. Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) exhibited a half-wave potential of 0.85 ± 0.01 V and an overpotential of 310 ± 1 mV, respectively. Meanwhile, the high-spin configuration of M1CO/CNTs downshifts the d-band center, accelerating *OH desorption during the ORR. Notably, the liquid Zn-air batteries equipped with M1CO/CNTs delivers a power density of 73.8 ± 0.1 mW cm-2 and a specific capacity of 832.8 ± 0.1 mAh gzn-1, with negligible voltage variation over 300 cycles. Furthermore, the flexible battery exhibits excellent deformation tolerance and low-temperature resistance. This study clarifies the intrinsic mechanism of enhanced oxygen electrocatalytic performance via site spin state regulation, offering a new strategy for developing spinel-based bifunctional electrocatalysts and high-performance Zn-air batteries.