Calcium-Mediated Fe─N Bond Reinforcement for Ultra-Stable Oxygen Reduction Reaction

The practical deployment of atomically dispersed Fe–N–C catalysts for the oxygen reduction reaction (ORR) is severely hampered by the electrochemical leaching of Fe active sites. Inspired by the stabilizing role of Ca²⁺ in metalloenzyme active sites, a novel Fe–Ca dual-atom sites catalyst (Ca/Fe–N–C) is constructed on amorphous porous carbon nanosheets. The introduced Ca atom acts as an “electronic modulator” and “structural stabilizer,” which effectively lowers the oxidation state of Fe and reinforces Fe–N coordination bond. This ingenious design results in an exceptional ORR catalyst with the half-wave potential of 0.912 V in alkaline media and unprecedented durability, exhibiting negligible decay after 80000 cycles. When integrated into Zn-air batteries (ZABs), the Ca/Fe–N–C-based cathode delivers a peak power density of 215 mW cm⁻² and sustains operation for exceeding 1110 h, markedly superior to benchmark Pt/C. This work not only unveils the pivotal role of alkaline-earth metals in stabilizing transition-metal sites but also establishes a general paradigm for designing durable atomically dispersed catalysts for advanced energy conversion devices.