CeO2の価数エンジニアリングによるFe/Co二原子触媒の酸素電気触媒性能向上

Dual-atom nitrogen-doped carbon catalysts have garnered considerable interest as air electrodes for rechargeable zinc-air batteries (ZABs), owing to their outstanding bifunctional oxygen electrocatalytic activity. Nonetheless, their practical implementation is hindered by durability issues during the oxygen reduction reaction (ORR), as the active sites are degraded by the oxidative by-products. Furthermore, the sluggish electron transfer obstructs the oxidation state transitions of Co/Fe centers to limit the oxygen evolution reaction (OER) activity. Here, the valence engineering is performed in CeO₂ redox modulator that is composed with Fe/Co dual-atom catalyst (FeCo─N─C), to resolve the stability and activity issues. The valence-engineered CeO₂ with a fast Ce⁴⁺/Ce³⁺ redox process can efficiently scavenge the highly oxidative by-products in ORR to improve the durability. In addition, the interaction of CeO₂ with FeCo─N─C can accelerate electron transfer and lower the Co redox potential during the OER. The ZABs assembled with optimized FeCo─N─C/CeO₂ as the air electrode display a maximum power density of 335 mWcm^-2 without significant deterioration after ≈1000 h of continuous cycling. Therefore, compositing with valence-engineered CeO₂ provides a simple and effective solution to resolve the stability and activity issues of FeCo─N─C as an air electrode.